msc thesis

Will ASECNA meet the needs of African

air navigation for the 21st century?

An analysis of ASECNA strategy for adopting advanced CNS/ATM

Department of Air

Transport Management

MSc THESIS

Academic year 2004-2005

Francis Fabien Ntongo Ekani

Supervisor: Rodney Fewings

CRANFIELD UNIVERSITYSCHOOL OF ENGINEERING

DEPARTMENT OF AIR TRANSPORT

MSc THESIS

Academic year 2004 - 2005

Will ASECNA meet the needs of African

air navigation for the 21st century?

An analysis of ASECNA strategy for adopting advanced CNS/ATM

By Francis Ntongo

Supervisor: Rodney Fewings

This thesis is submitted in partial fulfilment of the requirements for the degree of Master of Science

©Cranfield University 2005. All rights reserved. No part of this publication may be reproduced

without the written permission of the copyright owner

To My Parents

Abstract

This MSc thesis aims at investigating the rationale of implementing CNS/ATM1

systems in ASECNA area, a region of the African continent. The question of whether

ASECNA’s modernisation strategy will respond to African air navigation’s future

needs is essential to the region, as a performing system is a prerequisite for the

viability of air transport activities.

The study analyses the situation of service provision in the region and highlights the

needs and the priorities. It also assesses the suitability of future air navigation

systems, their ability to respond to these needs, and it provides an analysis of

ASECNA’s strategy.

The region is characterised by an insignificant level of traffic at a global scale. Local

air transport industry needs help to reduce its costs, as the majority of carriers are

struggling to survive in a context of combined low demand, and very high fuel prices.

There are a high number of air navigation incidents relatively to the level of traffic.

That is due to an inefficient system based essentially on conventional navigation

systems, which are very often unreliable and underperforming. The research reveals

the predominance of Safety, Efficiency and airspace Fragmentation as the primary

performance drivers for evolving the system. ASECNA is responding to its users’

needs by implementing future air navigation systems. CNS/ATM trials suggest that

the technology can respond to regional priorities as they bring greater efficiency,

increased capacity and safety, and enhanced cross border cooperation and cost

effectiveness. They are also suitable for inhospitable areas like in ASECNA.

Local airlines have limited means to upgrade their old fleets. Foreign carriers operate

high yield routes and generate 80 per cent of ASECNA’s revenues and operate young

well equipped aircraft. Therefore, the agency has developed a dual strategy, by

maintaining ground-based systems for small local carriers on domestic routes, while

introducing CNS/ATM systems on main areas of routing.

ASECNA will make the new systems available to its users, but it will not necessarily

be cost effective. However, the success of the implementation process also depends

on the ability of member states to upgrade and harmonise their legislations on time.

The slowness of legislative procedures and the lack of harmonisation in Africa will

delay the benefits, which is damaging to the industry.

1 Air Traffic Management supported by three components: Control, Navigation and Surveillance

Aéroport Du Cameroun (ADC)

Etablissement National de la Navigation

Aérienne (ENNA, Algeria)

Acknowledgement

I’d like to thank Rodney, my supervisor, for his constant support, his wise and

constructive critics and all the advices he gave me and that contributed to the success of

this thesis. Andy Foster and Simon Place also gave me a decisive support.

I’ll also like to thank Professor Fariba Alamdari, the Head of Air Transport Group, for

having made me to understand what management is about: Always being Positive and

getting the best from People.

Special thank to ASECNA for their precious and invaluable support throughout the

project, and for welcoming me during one week at their Head Quarter in Dakar,

Senegal:

Youssouf Mahamat, Director General

Amadou Guitteye, Director of Operations

Wodiaba Samake, Head of training office

And

Marafa Sadou, Special adviser to the director of operations

Diallo amadou Yoro, Head of Normalization office

Hilaire Tchicaya, Head of Aeronautical Telecommunication office

Ngoue Celestin, Head of Air Navigation

Sacramento Martin, Engineer, office of Statistics

Edmond Hocke Nguema-Biteghe, Head of Network Operations

Armand Boukono, Engineer, Normalization office

Ndobian Kitagoto, Engineer, Meteorology office

Aviation companies

Air Benin, Air France KLM

Air Inter Cameroon

Air Madgascar

Air Senegal international

Bellview Airlines, Cameroon Airlines

iii

Table of content

Abstract iAcknowledgement iiTable of Content iiiList of figures vList of tables viiiGlossary ix

Chapter 1 Introduction to thesis page 1

1.1 Background 11.2 Research questions 31.3 Objectives 41.4 Methodology 41.5 Structure of thesis 71.6 Data sources 71.7 Key assumption 71.8 Choice of performance measures 81.9 Summary 9

Chapter 2 ASECNA’s region Air Transport Industry 10

2.1 Economic characteristics 112.2 Transport infrastructure 132.2.1 Roads 132.2.2 Railways 132.2.3 Ports 142.3 Air Transport Industry 142.3.1 Airport Infrastructure 152.3.2 Airlines 162.3.3 Fleet 172.4 Regulatory 252.5 Air Travel Demand 262.6 Conclusion 32

Chapter 3 Air navigation Performance Review 34

3.1 Introduction 343.2 Airspace organization 343.2.1 Description of ASECNA’s strategy 343.2.2 Fragmentation 363.3 Traffic 383.3.1 Airport activity 383.3.2 En-route traffic 403.4 Delays 443.5 Impact of future trends 443.5.1 Prospects 44

iv

3.5.2 Impact on runway capacity 453.5.3 Impact on en-route capacity 463.6 Traffic complexity 473.7 Safety 483.7.1 Air Proximities 483.7.2 Users' claims 493.7.3 Birdstrikes 493.7.4 Safety Review System 503.8 Efficiency 503.8.1 Flight efficiency 503.8.2 Fuel efficiency 513.9 Cost effectiveness 543.9.1 Navigation charges 543.9.2 Air Navigation Costs 553.10 Cooperation 573.11 Training 593.12 Financing 593.13 CNS and Aviation weather management issues 603.13.1 Shortcomings of conventional systems 603.13.2 ASECNA's systems' performance 643.15 Conclusion 69

Chapter 4 CNS/ATM systems and concepts 70

4.1 Introduction 704.2 Suitable CNS/ATM systems for ASECNA 724.2.1 Geographic characteristics 724.2.2 Efficiency 724.2.3 Capacity for Safety 734.2.4 Surveillance 734.3 Study of selected systems 734.3.1 Communications 734.3.2 Navigation 834.3.3 Surveillance 924.3.4 Air Traffic Management 974.4 Transition phase 984.6 Affordability 994.7 Conclusion 100

Chapter 5 Analysis of ASECNA’s modernization strategy 102

5.1 Description of the strategy 1025.1.1 Communications 1025.1.2 Navigation 1035.1.3 Surveillance 1035.1.4 Systems on board the aircraft 1055.1.5 Aviation weather 1055.1.6 Air Traffic Management 106

v

5.1.7 Cooperation 1075.1.8 Training 1105.1.9 Financing 1105.1.10 Implementation schedule up to 2015 1125.2 Analysis 1135.3 Conclusion 115

Chapter 6 Recommendations and Conclusion 117

References 122

Appendix 1 Presentation of ASECNA 126

Appendix 2: Ground Based Navigation Systems Principles 1301 How the VOR works 1302 How DME works 1323 How ILS works 1334 Multilateration 134

Appendix 3 WGS-1984 136

Appendix 4 ASECNA’S Telecommunications Network 137

Appendix 5 Air Traffic Projected Growth by world region 138

Appendix 6 ICAO’s Navigation SARPs 139

Appendix 7 ASECNA’s Satellite Navigation Circuits 140

Appendix 8 ASECNA’S ATS/Direct Speech Network 141

Appendix 9 CNS/ATM: Drivers and Origins 142

List of Figures

Chapter 1

Figure 1.1 Short term evolution of crude oil 2

Figure 1.2 Analytical Framework of ASECNA’s performance analysis 5

Chapter 2

Figure 2.1 ASECNA area in this report 10

vi

Figure 2.2 Share of population and GDP by country 12

Figure 2.3 Stakeholders 15

Figure 2.1 Repartition of Aircraft types in Africa 18

Figure 2.2 Intra African market Fleet (Jets + Turbo Propellers) 19

Figure 2.3 African fleet annual utilization 20

Figure 2.4 African fleet Evolution from 2003 to 2023 21

Figure 2.5 RPK, ASK (Billion) and Passengers load factors in Africa 21

Figure 2.6 Trend in Aviation fuel cost 23

Figure 2.7 Yields and Unit costs in Key markets 23

Figure 2.8 African Airlines 1 Operating costs (Unit cost $ per tonne per Km) 24

Figure 2.9 Regional share of global international air passenger traffic 26

Figure 2.10 Evolution of passenger traffic (1994-2003) 27

Figure 2.11 Average Airport Passenger Traffic (2000-2004) 28

Figure 2.12 Evolution of Cargo traffic (1994-2003) 31

Chapter 3

Figure 3.1 ASECNA’s Flight Information Regions 37

Figure 3.2 Number of flights from 1993 to 2003 38

Figure 3.3 Number of aircraft movements at 15 key airports 39

Figure 3.4 Areas of Routing 41

Figure 3.5 Average number of flights controlled per hour and per controller 43

Figure 3.6 Projected growth over the next decade 45

Figure 3.7 Projected runway occupancy in ASECNA’s main airports 46

Figure 3.8 Projected controllers’ productivity in 2015 47

Figure 3.9 Evolution of Air Proximities 48

1 Flight Equipment comprises maintenance, insurance, and rental. The others operating expenses are not mentioned here. But it’s interesting to note that administration unit costs for non efficient airlines are extremely high, almost twenty times higher than an efficient airline’ unit costs.

vii

Figure 3.10 Evolution of incidents during the last six years 49

Figure 3.11 Flight paths between Douala and Dakar 51

Figure 3.12 The different phases of a flight 52

Figure 3.13 Evolution of air navigation charges 54

Figure 3.14 Personnel, ANS and transport costs from 1996 to 2003 55

Figure 3.15 Evolution of the average cost per flight from 1996 to 2003 56

Figure 3.16 Evolution of en route revenues from 1996 to 2003 57

Figure 3.17 Regional fragmentation of ATM sectors 58

Figure 3.18 Financial results from 1994 to 2003 59

Figure 3.19 OPMET availability rate 68

Chapter 4

Figure 4.1 Communication links in ASECNA 74

Figure 4.2 CPDLC test message 75

Figure 4.3 Estimated capacity gained as a function of % of CPDLC equipage 76

Figure 4.4 Aeronautical telecommunications network concept 82

Figure 4.5 Comparison between EGNOS and GPS 85

Figure 4.6 Lateral and Vertical Total System Error 87

Figure 4.7 Comparison between RNAV, RNP and conventional navigation 89

Figure 4.8 Atlanta SID trials: Non RNAV tracks 90

Figure 4.9 Atlanta SID trials: RNAV tracks 90

Figure 4.10 Projected RNP-RNAV capable aircraft 91

Figure 4.11 ADS-B operational capabilities 94

Figure 4.12 ADS-B performances Vs Radar 96

Chapter 5

Figure 5.1 Classification of CNS/ATM expenditure 112

Figure 5.2 Possible Airspace redesign by 2030 115

viii

Appendices

Statutory structure 128

External representations’ organisation chart 129

VOR station 131

World Geodetic System 136

ASECNA’s Telecommunication Network 137

ASECNA’s Satellite connectivity 140

ASECNA’s ATS/DS network 141

Evolution of CNS/ATM implementation 145

List of Tables

Table 2.1 Comparative GDP and Population 11

Table 2.2 Situation of aircraft operated in the world 19

Table 2.3 Daily passenger traffic between city pairs 29

Table 2.4 International traffic at major regional airports 30

Table 3.1 The main airstream in ASECNA 40

Table 3.2 Traffic by FIR 40

Table 3.3 Average traffic density from 2001 to 2003 42

Table 3.4 Average traffic density by 2015 46

Table 3.5 Average ANS cost per flight in Europe, ASECNA and the USA 56

Table 3.6 Equipments availability 65

Table 3.7 Air circulation control: controlled routes 67

Table 4.1 Workload reduction as a function of aircraft equipage 77

Table 4.2 Delays reduction as function of aircraft equipage 77

Table 4.3 Results for lateral and vertical accuracy with EGNOS 87

Table 4.4 Results for availability during trials Vs ICAO’s SARPs 87

Table 4.5 ICAO’s SARPs for lateral and vertical accuracy 87

ix

Glossary

A

ACC Area Control Centre

ADS Automatic Dependent Surveillance

ADS-B Automatic Dependent Surveillance Broadcast mode

ADS-C Automatic Dependent Surveillance Contract mode

AFI Africa Indian ocean area

AFS Aeronautical Fixed Service

AFTN Aeronautical Fixed Telecommunication Network

AIS Aeronautical Information Service

AMS(R) S Aeronautical Mobile-Satellite (R) Service

AMHS Aeronautical Mobile Handling System

AMSS Aeronautical Mobile-Satellite Service

ANSP Air Navigation Service Provider

AOC Airline Operation Centre

APIRG AFI Planning and Implementation Regional Group

APV Approach with vertical guidance

AR Area of routing

ASECNA Agency for Security, Aerial Navigation in Africa and Madagascar

ASM Airspace Management

ASK Available Seat Kilometre

ATC Air Traffic Control

ATFM Air Traffic Flow Management

ATM Air Traffic Management

ATN Aeronautical Telecommunication Network

ATS Air Traffic Services

ATS/DS Air Traffic Services Direct Speech

C

CDM Collaborative Decision Making

CDMA Code Division Multiple Access

CFIT Controlled Flight Into Terrain

x

CNS/ATM Communications, Navigation, Surveillance / Air Traffic Management

CPDLC Controller pilot data link communications

D

DECCA A low frequency hyperbolic radio navigation system

DFIS Data Link Flight Information Services

DME Distance Measuring Equipment

E

EGNOS Eurpean Geostationary Navigation Overlay Service

EUR European Region

EUROCAT Thales ATM (Commercial organisation) air traffic management

automation product

F

FAF Final Approach Fix

FANS Future Air Navigation Systems

FIR Flight Information Region

FDPS Flight Data Processing System

FL Flight Level

FMS Flight Management System

G

GLONASS Global Orbiting Navigation Satellite System (Russian Federation)

GNSS Global Navigation Satellite System

GPS Global Positioning System (United States)

H

HF High Frequency

HFDL High Frequency Data Link

I

IATA International Air Transport Association

ICAO International Civil Aviation Organization

IFR Instrument Flight Rules

ILS Instrument Landing System

xi

INS Inertial navigation system

ITU International Telecommunication Union

L

LORAN Long Range Air Navigation

M

MET Meteorological services for air navigation

METAR Aviation routine weather report

MLS Microwave Landing System

MODE S Mode Select

N

NDB Non-directional beacon

NOTAM Notice To Airmen

NPA Non-precision approach

NSE Navigation System Error

O

OPMET Operational Meteorology

P

PDN Paquet data Network

PIRG Planning and Implementation Regional Group

R

RIMS Ranging Integrity Monitoring Station

RNAV Area Navigation

RNP Required Navigation Performance

RPK Revenue Passenger Kilometre

RTK Revenue Tonne Kilometre

RVSM Reduced Vertical Separation Minimum

S

SAM South American Region

SARPs Standards and Recommended Practices

SAS Scandinavian Airways

xii

SAT South Atlantic

SATCOM Satellite Communication

SBAS Satellite-based augmentation system

SID Standard Instrument Departure

SIGMET Significant Meteorological event

SIGWX Significant Weather

SITA Société Internationale de Télécommunications Aéronautiques

SSR Secondary Surveillance Radar

T

TACAS Terminal Access Controller Access Control System

TACAN Tactical Air Navigation

TAF Terminal area forecast

TDMA Time Division Multiple Access

TMA Terminal Manoeuvring Area

TSE Total System Error

V

VDL VHF Data Link

VFR Visual flight rules

VHF Very High Frequency

VOR VHF Omnidirectional Radio Range

W

WGS-84 World Geodetic Reference System 1984

1

Chapter 1 : Introduction to Thesis

The aim of this chapter is to introduce the research topic and to present the objectives and the methodology used to respond to the research question.

1.1. Background

Agency for Air Navigation Safety in Africa (ASECNA1) is a regional publicly held

establishment that provides navigation services to 15 West and Central African

Countries2, plus Madagascar and the Comoro islands in the Indian ocean.

The region is relatively poor. Economic characteristics are those of developing

countries. Some of the less advanced countries are located there.

ASECNA covers an area of 16 million square kilometres3, most of which is unoccupied

and dominated by the Sahara desert, oceans and forests.

The Air Transport Industry has changed significantly over the past decade. These

changes were dictated by a combination of factors, mainly operational and financial,

following a succession of crisis4. The airline industry is increasingly sensitive to the

cost of doing business.

Efficiency

Air carriers demand direct routes, flight level optimization, efficient in-flight and

improved en-route fuel5 consumption. Figure 1.1 below shows the projected upwards

evolution of crude oil prices. That means airlines’ fuel bill will significantly increase.

Cost reduction is one aspect of mitigating the effects of fuel high price. It explains why

airspace users want more efficiency. It is one of the factors that led them to incite

suppliers, such as air navigation service providers (ANSP) to improve their

effectiveness and the quality of service provision.

1 In the present study designates both the agency or the geographic region2 Benin, Burkina Faso, Cameroon, Central African Republic, Chad, Congo Brazzaville, Equatorial Guinea, Gabon, Ivory Cost, Mali, Mauritania, Niger, Senegal, Togo. France is also an observer member.3 Equivalent to almost 66 times Great Britain size.4 September Eleven, SARS, Bird Flu, Second Golf War…5 Crude oil price was around 50 dollars per barrel in 2005

Chapter 1 Introduction to Thesis

2

Figure 1.1: Short-term evolution of crude oil prices

Source: IATA, 2006

Capacity

Air travel and air traffic are continuously growing. The number of aircraft movements

has increased by 5.3 per cent per year on average over the past 15 years in ASECNA

region, which is in line with worldwide trends. The growth is forecast to continue at an

estimated yearly pace of 5 per cent. That activity means an increasing pressure will be

put on airports and air navigation systems, which may raise airspace and airport

capacity concerns.

Safety

Safety records are worrying in Africa. The continent represents only about 3 per cent

of global traffic. Nevertheless, statistics show that almost one third of fatal accidents

over the past ten years occurred in Africa according to IATA.


3

Air Transport is a catalyst for development and trade. Efficiency, Capacity and Safety of

air navigation systems are therefore strategic components for a viable regional6 air

transport industry and growing national economies.

The important question is whether ASECNA will manage to overcome the current and

future challenges. Will they respond to users’ requirements while delivering a safer

service, in the interest of regional air transport?

The agency has embarked on a modernisation programme since 1994. It is

implementing modern air navigation systems, known as Future Air Navigation Systems

(FANS) or CNS/ATM (Control, Navigation, Surveillance and Air Traffic

Management).

CNS/ATM systems are a complex and interrelated set of technologies and concepts

largely based on satellite communication. They are the response brought forward by the

aviation community, under the aegis of the International Civil Aviation Organisation

(ICAO), in response to the challenges described above. Regional work groups have

been put in place to coordinate efforts. ASECNA is member of AFI7 Planning and

Implementation Regional Group (APIRG), which regroups African and Indian Ocean

countries

The thesis intends to investigate current systems’ performance in ASECNA. It

highlights regional shortcomings and needs, and examines the agency’s modernisation

strategy, CNS/ATM adopted solutions, and their implications on service provision for

the next 15 years.

1.2. Research Questions

The main research question of the thesis is: Will ASECNA meet the needs of African

Air Navigation for the 21st Century?

Responding to that question requires that the following intermediate questions are dealt

with:

6 ASECNA region7 Africa and Indian Ocean


4

1. What are the needs and the priorities of African Air Navigation for the 21st

century?

2. Are CNS/ATM systems the suitable tool with regard to regional characteristics?

3. Will ASECNA’s modernisation strategy respond effectively to the needs?

1.3. Objectives

The objectives of the study are to:

1. Examine the state and the performance of air navigation service provision in

ASECNA

2. Study the potential benefits of CNS/ATM systems to the region

3. Analyse ASECNA’s modernisation plans

1.4. Methodology

This research is based on an analytical approach to assessing ASECNA’s capability to

respond to airspace users’ needs and requirements and regional air transport’s interests.

To answer to the first research question that aims at defining the needs and the

priorities of African Air Navigation, we process as follows:

First, the region’s air transport industry is assessed. This is done by examining local air

transport characteristics:

1. Analysis of air travel demand

2. Assessment of air carriers types

3. Examination of air carriers performance

4. Examination of airport and alternative transport infrastructures

5. Overview of regulations and the factors that influence air traffic.

Secondly, the air navigation system’s performance is studied, by analysing key

performance areas and related indicators:


5

1. Traffic demand, Capacity, Delays

2. Complexity, Safety, Aircraft proximities

3. Performance of CNS and Met systems.

4. Fragmentation, Cost Effectiveness

5. Flight efficiency

6. Cooperation.

The analytical framework used is described in figure 1.2 below. The structure is based

on a model developed by the Eurocontrol Performance Review Commission to assess

European Air Traffic Management performance. It has been adapted for the present

study.

Figure 1.2: Analytical Framework of ASECNA’s performance analysis

Source: Eurocontrol, Performance Review Report 8, 2005

Complexity

Trafficdemand

Capacity

Fragmentation

AIRPROX

CNS Met Systems

Availability

Delays

Productivity

Service provision

cost

Safety

CostEffectiveness

Flight Efficiency

Cooperation

ASECNA performance

PerformanceDrivers

Performance indicators

Drivers

ANS Key performance Areas


6

Finally, the impact of traffic growth is estimated. We apply forecasted growth rates to

current data, in this case 2003.

To answer to the second research question, which aims at determining the relevance of

CSN/ATM systems in ASECNA, we adopt the following method:

Based on the system’s deficiencies and local characteristics drawn from the previous

performance analysis:

1. Identification of potentially suitable CNS/ATM technologies and systems based on

FANS performance during worldwide trials. These trials are performed under certain

geographic and operational conditions; some of them match ASECNA area’s

characteristics.

2. Their affordability is assessed

At last, the third research question is dealt with as follows:

1. Assessment of the technology solutions adopted

2. Assessment of the implementation process, and we analyse the strategies in the

areas listed below:

a. Communication

b. Navigation

c. Surveillance

d. Met

e. Air Traffic Management

f. Training

g. Programme financing

h. Cooperation

3. Assessment of the timeframe by confronting the predicted timetable and realized

projects.


7

When quantifiable data are not available, interviews allow to have an idea of the

situation. Interviewees are ASECNA’s high profile staff, airlines directors, and other

ANSPs’ personnel.

1.5. Structure of Thesis

The choice of performance areas is discussed in chapter 1. The overview of ASECNA

region’s air transport industry is discussed in Chapter 2. An insight of regional

characteristics is given, which provides a better understanding of the operational

environment and the context, as well as the importance of a performing air navigation

system for the region. A detailed analysis of air navigation systems’ performance is

provided in Chapter 3. Local navigation characteristics are discussed, and predefined

performance areas presented in chapter 1 are examined. That allows highlighting the

areas that require improvements and to define what should be the priorities for the

region. Chapter 4 presents CNS/ATM systems and concepts and looks at their potential

benefits, with regard to local characteristics. Finally, the strategy adopted by the agency

to respond to those priorities is examined in chapter 5.

1.6. Data Sources

The instruments for this study include a one week visit to ASECNA’s headquarter in

Dakar, Senegal, to collect data and documents, to discuss with professionals involved in

daily operations and to observe the actual state of the implementation of the strategy on

the ground. Telephone interviews, email-statements, internet documentation are

intensively used. Key internet documents come from ICAO, ASECNA, IATA, and

CANSO8’s CNS/ATM related literature.

1.7. Key Assumptions

The geographic boundaries of the study are clearly the region covered by ASECNA.

However, as ASECNA9 is part of the wider geographic entity, the study of this region

naturally implies to investigate its interactions with the neighbourhood.

8 Civil Air navigation Services Organisation9 Seen here as a region, not the organization itself


8

A key assumption in the study is that average economic and air traffic prospects that are

applicable to the African continent are applicable to ASECNA. This is a sensitive

approach as the economic characteristics of the region are similar to the continent’s

patterns. However, the average growth figures may be driven up by air transport leading

countries. In particular, air transport is less developed in ASECNA then Southern,

Eastern Africa, and North Africa.

Another key assumption is that the relative importance of individual countries’ air

transport performance is frozen over the period studied. Therefore, the relative

importance of airports size and spatial distribution of traffic flows within the region is

supposed to remain unchanged.

1.8. Choice of performance indicators

A large number of indicators could be used to assess ASECNA’s performance. How

ever, for this study, several factors influenced the choice of indicators:

The availability of data: several other indicators could have been used but ASECNA

does not collect the corresponding data. Moreover, some chosen indicators could have

been broken down into more detailed data, but that has not been possible.

The effectiveness of chosen indicators in assessing an ANSP’s performance:

Safety, Capacity, Flight efficiency, Cost Effectiveness, cross border cooperation are

aspects of an ANSP operation that effectively evaluate the quality of service provision.

Safety

Safety performance measures are hardly available in ASECNA. However, indicative

incidents reports are used to assess the safety level. A comparison with other Regions’

safety records with respect to the level of traffic gives an idea of ASECNA’s

performance.

Capacity

Capacity is closely related to delays and the level of traffic. Although delays data are

not available, interviews allow having an idea of influent factors.


9

Flight Efficiency

The availability of a maximum number of direct routes and the possibility to chose

optimum flight levels are crucial to airlines as it allows reducing their fuel bill.

Cost effectiveness

The bill paid by airlines for service provision depends on ASECNA’s ability to maintain

low operating costs.

Cooperation

The level of technical and political cooperation indicates how states and ANSPs work

together to avoid unnecessary costs to airlines, and make the airspace as seamless as

possible.

1.9. Summary

This chapter laid the foundations for the thesis. It introduced the research problem and

questions: Will ASECNA meet the needs of the African Air Navigation for the 21st

century? In addition, what are the problematic and the challenges related to the

achievement of that mission? The research was justified, and the methodology, based on

an analytical approach was detailed. Performance indicators have been presented and

discussed. Key assumptions were presented.

10

Chapter 2: ASECNA’s Air Transport Industry

The aim of this chapter is to find out the region’s air transport industry’s characteristics.

This is an important step as it helps to understand in which environment ASECNA

evolves, and the factors that may influence its activities. Further details on ASECNA as

an organization and its history are included in appendix 1.

Figure 2.1: ASECNA area in this report

Source: ASECNA

Chapter 2 ASECNA’s Air Transport Industry

11

2.1 Economic Characteristics

ASECNA comprises developing countries, mainly located in western or Central Africa,

except Madagascar and the Comoros Islands located in the Indian Ocean (See map

above). Their Economies are relatively weak. Mali, Niger, Chad, Burkina Faso Togo

and the Central African Republic (CAR) are among the poorest country in the world.

The general picture is one of underdevelopment, political instability, economic

volatility and high poverty. Comparative Gross Domestic Products and populations

between ASECNA, the world average and UK’s performance reflect that situation

(Table below).

Region GDP

($ billion)

GDP /Capita

($ thousand)

Population

(million)

ASECNA1 93 1.7 141

WORLD 43920 9.5 6,526

UK 2218 31 60

Table2.1: Comparative GDP and populations;

Source: CIA World fact book, 2006

The region accounts for just 0.2 per cent of world GDP. But in contrast to its low share

of economic activity worldwide, as the table above shows it, 141 million people live in

ASECNA, which is 2.2 % of world population. That combination of low input and high

population means the GDP per capita in ASECNA is the lowest among the world

regions (1700 dollars). UK for instance is 24 times wealthier, and its GDP per capita is

26 times ASECNA’s average. 46 per cent of the population lives under the poverty line

in the region.

Countries in ASECNA remain to a large extent producers of raw materials. They export

agricultural goods such as coffee, cocoa and cotton, or mineral such as crude oil and

copper. Trade exchanges in ASECNA region tend to be dominated by agricultural

exports.

1 Data compiled from CIA world Fact book 2006


12

However, economic development is not homogeneous within the region. Noticeable

disparities between countries exist. For example, while Equatorial Guinea represents

only 0.4 per cent of regional population, it accounts for 8.3 per cent of GDP. In

contrast, Madagascar that contains 13 per cent of total population accounts only for 4.9

per cent of regional GDP. (Figure 2.2)

Figure 2.2: Share of Population and GDP by country

02468

101214161820

Mad

gasc

ar

Ivory

Coa

st

Camer

oon

Burkin

aNige

r

Seneg

alMal

i

ChadBen

inTog

oCAR

Congo

Maurit

ania

Gabon

Comor

os

Equat

orial

Guin

ea

(pe

rce

nta

ge

)

% Population %GDP

Source: CIA fact book 2006

Ivory Coast, Cameroon, Senegal, Gabon and Equatorial Guinea account for almost 60

percent of ASECNA GDP and one third of the population, while Comoros, Niger,

Mauritania, Togo, and CAR own 9.3 per cent of GDP and host 20 per cent of

population.

Regional integration processes are on the way. ASECNA members countries located

in West Africa are part of ECOWAS (Economic Community of West African States).

Those located in Central Africa are members of CEMAC (Central Africa Economic and

Monetary Union). The level of integration varies significantly. The ECOWAS is much

more advanced than the CEMAC. But the two entities are confronted to the economic


13

disparities described above, which slow the pace of integration. The lack of a real

political will in CEMAC, or persisting political instability and civil wars in key

countries such as Ivory Coast, and the Republic of Congo have also had a damaging

impact on regional economic and political integration.

In other respects, bad Governance is a common practice at the state level and in public

companies. States continue to own a high number of companies in strategic sectors such

Telecommunications, Water, Energy and Transports, although privatisations are

spreading across the region, mainly on the basis of International Monetary Funds

Recommendations (IMF). It is generally admitted that state ownership, “poor

management and monitoring, and anti-competitive arrangements have bred corruption

in Africa” and particularly in the ASECNA area (Morrell, 2005)

These factors, combined with the low level of investments (Foreign Direct Investments

are among the lowest in the world), contribute to explain the underdevelopment of basic

infrastructures, particularly in the transport sector.

2.2 Transport infrastructure

2.2.1 Roads

Roads are the predominant mode for freight and passenger transport in Africa (World

Bank, 2005). But within individual countries, very often, only the main cities are linked

by paved roads. Regional interconnection is very limited. There are only 39,000

Kilometres of paved roads in the entire region, which represents 18 percent of total road

network. Moreover, these roads are often in a relatively bad state due to poor

maintenance. In comparison, UK alone has 392,931 Kilometres of highways, which is

ten times more. That situation renders economic exchanges very difficult and slows

their intensity as well as it limits regional integration.

2.2.2 Railways

Railway links are very poor or do not exist within and between countries. Two third of

the actual rail infrastructure were inherited from the colonial period (OEDC, 2005,

P.22).


14

There are only 8228 Kilometres of railways in ASECNA countries (17300 in the UK).

Some states such as Niger, Chad, Equatorial Guinea, Comoros, and CAR have simply

no railway infrastructure, which means their economic activity depends heavily on the

road system.

2.2.3 Ports

There are a dozen key ports in ASECNA. The most important of them is Dakar, with

about 10 millions tonnes of goods. The essential of ASECNA countries trade activities

is carried out through these ports. For instance, 98 per cent of exchanges between

Cameroon and the outside world are done through Douala autonomous port, with about

5.2 millions tonnes per year (Mission Economique, 2006)

But, the reliability and the speed of exchanges of goods and mobility of people is a

crucial factor for regional integration. Given the under performance of road, and rail

systems, and the slowness of sea transport, the availability of an adequate air transport

infrastructure is therefore of paramount importance for ASECNA countries as they try

to integrate into the world economy.

2.3 Air Transport industry

A developed air transport industry is a driving force for economy, and a catalyst for

development and trade. It facilitates exchanges between countries in which air

transport substitutes, the road and rail systems are underdeveloped.

Passenger aviation is the principle mean of transport for business and tourism travellers.

Airports link the movement of passengers and goods to national economies; they serve

as a primary hub for the tourism industry, and as key logistical centre for international

trade.

Stakeholders in ASECNA are the states, airlines, ANSPs, airports and international

institutions. The study focuses on the relation between ANSPs and other stakeholders

(Figure 2.3).

States are represented by civil aviation authorities and Governments. They make air

transport policies, on the basis of strategic objectives, through legislations applying to

all the others stakeholders in the region.


15

Airlines are of different types: International, Domestic, and Regional. Both ASECNA

originated airlines and the others are considered.

Airports are divided into main and secondary airports.

The region only air navigation service provider is ASECNA. The institution has links

with others neighbouring ANSPs.

Figure 2.3: The stakeholders2

2.3.1 Airport Infrastructure

Main Airports

The airport infrastructure (airstrips, air terminals, aircraft hangars) of ASECNA member

states comprises about 25 international airports (2400 to 3500 m of tarred runways)

regularly used. The main airports are Dakar, Abidjan, Douala, Libreville, Brazzaville

and Antananarivo. They are served by major regional, continental and intercontinental

airlines. The service provided is acceptable, but is far from being good.

The airport sector is not free from financing, safety and security problems. Built for the

most part in the 1960s and 1970’s, they present deficiencies. These vary from State to

State. Runways are generally in a bad state, taxiways and parking areas are often

2 All the stakeholders are not taken into account: Ground Handling, Maintenance, Catering… etc

Air Navigation Provider

ASECNA

AirlinesDomesticRegional

International

Policy MakersGovernmentsCivil Aviation

AuthoritiesLegislationsInstitutions

Policy Objectives

AirportsMain

Secondary

Other ANSProviders

Cooperation

Performance

Air TravelCustomers

Chapter 2 Asecna’s Air Transport Industry

16

unsuitable; passenger terminals are cramped or saturated in peak hours. There are

insufficient cargo hangars, refrigerating warehouses and fencing (African Union, 2005).

There are needs for the updating of these installations to meet international standards.

The inexistence of airport fences or in disrepair poses serious security and safety

problems.

Secondary Airports

The region counts about 150 domestic airports (runways of 1000 to 2000 m, usually

unpaved) and about 200 other national aerodromes (poorly maintained), with for several

of them inexistent traffic. These airports do not often have adequate navigation aids, or

basic airport commodities, which constrains their accessibility.

2.3.2 Airlines

In West Africa, and particularly in ASECNA, the liquidation of Air Afrique after 40

years of existence marked the end of a symbol of African airline integration.

Data from Air Transport Intelligence show that nearly 81 per cent of airlines serving

ASECNA are African. 50 per cent are from member states and 31 per cent from other

continents.

The main local carriers are Air Madagascar, Air Senegal international, Cameroon

Airlines, Air Gabon, Air Ivoire, Air Burkina, Air Mauritania, Air Togo, and Toumai Air

Tchad.

Domestic Airlines

The poor domestic markets are served by national carriers or very small companies of

which the fleet is often constituted by a single aircraft.

Regional Airlines

Air Senegal International, Bellview (Nigeria), Air Ivoire, Cameroon Airlines, Toumaï

Air Chad and Air Burkina have put in a lot of efforts to fill up the vacuum left following

the demise of Air Afrique. These airlines propose flights to travel within the region

from and to the main cities in the regions.


17

International Airlines

The region can be divided into two groups of countries:

1) Those that no longer have national long-haul carriers with their market largely

dominated by foreign companies.

2) Countries that still have national airlines but these are facing strong competition

from foreign companies (Cameroon, Gabon, and Madagascar).

Local Airlines

Cameroon Airline, Air Gabon, Air Madagascar and Air Senegal International are the

three main local flag carriers. They link the respective countries to Africa and mainly

Western Europe and less regularly the Middle East (During the hajj3)

Foreign Airlines

Air France-KLM is the dominant carrier on the long haul market. It serves all

ASECNA’s main airports. Swiss, SN Brussels, Iberia, Lufthansa and Alitalia also

regularly flight to the region. An important figure to highlight is the percentage of

international traffic ensured by Western airlines. In fact, according to ASECNA about

80 per cent of the commercial traffic is operated by these carriers4.

The Libyan carrier, Afriqiyah Airways is now operating to most of the defunct Air

Afrique member countries transforming Tripoli into a hub for passengers connecting to

Europe and the Middle East. Tunisia has also started flying to Bamako and Abidjan.

Royal Air Maroc (RAM) has opened routes to Dakar, Douala and Gabon.

Ethiopian, South African Airways, Kenyan Airways and Air Inter5 also have regular

connections with ASECNA.

2.3.3 Fleet

A study by Boeing showed that about 75 per cent of African fleet is composed by

regional jets or single aisle aircraft (Boeing, 2005). This does not take into account

secondary airports exclusively exploited by very small aircraft (Less than 30 seats).

3 Pilgrimage to Mecca4 Air France-KLM, TAP, Alitalia, SN Bruxels, SWISS, Iberia, Lufthansa…5 South African carrier


18

Most intra African routes are operated with narrow bodies, or very small jets or turbo

propellers.

Figure 2.4: Proportion of Aircraft types in Africa

Source: Afraa, 2005

41578%

9217%

245%

Jets Turbo PropellersSmall size aircraft


19

Figure 2.5: Intra African market Fleet (Jets + Turbo Propellers)

Source: Ambraer, 2006

New Average Old Total % of OldAfrica 162 111 316 589 54

America 1654 2581 1301 5536 24Europe 1768 1363 237 3368 7

Asia 1154 969 295 2418 12Middle East 240 144 155 539 29

Pacific 155 102 15 272 6WORLD TOTAL 5371 5529 2712 13 612 20

Table 2.2: Situation of aircraft operated in the world

Source: African Union, 2006

About 54 % of aircraft operated in Africa are considered to be old or very old. Nearly

45 % of aircraft are more than 15 years old. 20 % are between 10 and 15. 13 % are aged

between 5 and 10. Around 22 % are less than 5 years olds (figure 2.5). The average age

of the fleet is comprised between 16 and 20 years old. A large proportion of aircraft

still operated are aged over 25 and even 30. These aircraft are largely fuel inefficient.


20

Figure 2.6: African fleet annual utilization

Source: Ambraer, 2006

The average annual utilization is 1167 hours per aircraft. There is a strong correlation

between fleet utilization and fleet age (Coefficient of correlation equal to “- 0.8”).

0

500

1000

1500

2000

2500

3000

TP20 TP35 J35 J44 TP50 J50 TP70 J70 J80 J100 J120 J150 J175 J250 J>300

(Flights Hours per Aircraft)

0

5

10

15

20

25

30

35

40

45Fleet age (Years)

African annual fleet utilization African Fleet Average Age


21

Figure 2.7: African fleet Evolution from 2003 to 2023

Source: Airbus, 2005

Airbus estimates that African airlines will take delivery of about 641 new aircraft to

replace the current fleet or to sustain growth (Figure above).

2.3.4 Performance

Figure 2.8: RPK, ASK (Billion) and Passengers load factors in Africa

Source: AFRAA, 2005

Load factors, RPK and ASK are improving. But the overall industry’s health remains

critical in Africa. Load factors may look remarkably high, but they highlight the

airlines’ dilemma in the African operating climate. The problem is that break even load

factors remain higher.

0

200

400

600

2003 2023

GGrroowwtthh

SSttaayy

339922

770011

309

332

60Source: GMF 2004

664411 aaiirrccrraafftt

RReeppllaacceedd


22

Financial Performance

A sample of 8 airlines serving ASECNA region, comprising South African Airways,

Royal Air Maroc, Ethiopian Airlines, Kenya Airways, Air Mauritius, Bellview airways,

and Tunisair, made a net profit of over $200 million in 2005 (AFRAA, 2005, p.4).

These are encouraging and remarkable results in a world where airlines made huge

losses in the recent past But they do not reflect the real picture of the industry’s

performance. Most airlines, some very small, some bigger, are facing serious

difficulties.

Excessive debts, uncoordinated operating networks, liquidation, bankruptcy, are

examples of discrepancies generally observed (African Union, 2005). Airlines post very

poor financial results. The issue of profitability is crucial in the region: as the

market is narrow; it is difficult for local airlines to raise the necessary investment

required by the standards of modern airlines. These airlines often operate the same

routes. That competition leads to a price war resulting merely in weakening the

economic health of these companies which have difficulties in covering their operating

costs. Air Afrique6 best represents the airline industry’s situation in the area. Air

Afrique officially lost 194 million dollars between 1984 and 1996. It almost never made

significant profit. In 2002, after years of financial crisis, the 11 states that owned the

pan-African airline decided to file for bankruptcy. The Bankruptcy came after the

failure of a restructuring plan brokered by the World Bank.

The Yaoundé treaty countries have revised their national carriers by designating them

as the flag carriers. But they are left under the control of private interests, like Air

Ivoire, Air Senegal International, Toumaï Air Chad… etc. Cameroon Airlines and Air

Gabon, once the two leading carriers in the region, are now being liquidated or

privatized.

High Fuel prices

Fuel price is constantly rising. Fuel represents on average 25 per of operating costs. One

barrel costs on average 70$ world wide and up to 90$ in Africa (2005). The trend is

6 Air Afrique was established in 1961 to provide passenger and cargo service within the 12 West African Nations of Benin, Burkina Faso, Central African Republic, Cote d'Ivoire, Congo, Mali, Mauritania, Niger, Senegal, Chad, Togo & Guinea Bissau.


23

expected to last. These sky-rocketing fuel prices are devastating the industry. As airlines

are struggling to improve their bottom lines, fuel efficiency is critical.

Figure 2.9: Trend in Aviation fuel cost


Yields and Unit Costs

Figure 2.10: Yields and Unit costs in Key markets

0,0

2,0

4,0

6,0

8,0

10,0

12,0

14,0

Europe SouthernAfrica

Europe WesternAfrica

Within Europe North Atlantic

Yield Unit Cost Yield Cost Margin



24

Yields are declining and the margins remain low. The Southern Africa – Europe market

has the lowest unit cost but also the lowest yields, and the lowest margins. Europe –

Western Africa is a healthy market for efficient airlines, mainly European, with

relatively high yields. Yields are also low in the domestic market. The industry is not

expecting a significant improvement of yield.

Most African airlines are inefficient. This results into high unit costs as the figure below

shows it. These airlines possess old fleets which are highly oil-consuming. High unit

costs reflect low aircraft utilization rates, high maintenance, rental and insurance costs.

High air navigation and airport unit costs reflect their old avionics, and their low aircraft

utilization.

Figure 2.11: African Airlines 7 Operating costs (Unit cost $ per tonne per Km)

0

0,1

0,2

0,3

0,4

0,5

0,6

Fuel & Oil Flight Equipment Airport and NavigationCharges

Avg inefficient Airline Avg Efficient Airline Avg Efficient Worldwide


7 Flight Equipment comprises maintenance, insurance, and rental. The others operating expenses are not mentioned here. But it’s interesting to note that administration unit costs for non efficient airlines are extremely high, almost twenty times higher than an efficient airline’ unit costs.


25

2.4 Regulatory

In the absence of valid local carriers, ASECNA states have liberalized their skies

because bilateral agreements (Principle of reciprocity) are no longer functioning.

Although the deregulation process is on the way, with the ongoing implementation of

the Yamoussoukro8 liberalisation decision, the open sky agreements, civil aviation

codes are still obsolete and not harmonised. Texts on competition are not fully applied:

Current regulations impose restrictions over the number of operating airlines, and

frequency and capacity.

Western carriers want more liberalization, and would like to see the process speeded up,

as they are in a position to dominate the market further.

8 Ivory Coast, 1999


26

2.5 Air Travel demand

2.5.1 Traffic figures

Africa accounts for about 3% of global air traffic in term of Passenger Kilometres

performed (African Union, May 2005).

Figure 2.12: Regional share of global international scheduled air passenger traffic

Percentage share by region ( Passenger-kilometres performed in millions, 2004)

587,998 (29%)

64,326 (3 %)

785,828 (39%)

88,027 (4%)

354,353 (18%)

132,934 (7%)

Europe Latin America and CaribbeansNorth America Middle EastAsia Pacific Africa

Source: UNESCAP, 20059

This situation reflects its low income, and the lack of air transport infrastructure. This

being said, the situation of air transport in Africa is not uniform. It varies from one

region to another. Northern, Southern and Eastern Africa’s air transport performance is

good (Kenyan airways, South African, Ethiopian and Royal Air Maroc). ASECNA area

remains in a difficult situation with less traffic and unreliable structures. ASECNA’s

figures show that the region generates about 7 million passenger traffic per year (2003),

which is below what South Africa alone represents in term of annual air passengers.

9 United Nation Economic and Social Commission for Asia Pacific


27

Propensity to travel

Given the low level of incomes, and the widespread of poverty across the region, the

propensity to travel is very low. Moreover, the tariffs are “very high”, 20 to 30% higher

than the rest of the world according to the African Union. High air travel fares reflect

the low level of traffic, and limited load factors in most of the routes. Moreover, there

are little frequencies between city pairs. That increases aircraft operating costs.

Passenger Traffic10

Figure 2.13: Evolution of passenger traffic (1994-2003)

7,3

4,0

0,0

1,0

2,0

3,0

4,0

5,0

6,0

7,0

8,0

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

(Year)

(Millio

n P

as

se

ng

ers

)

Source: ASECNA, annual reports (1994-2003)

Passenger traffic has grown by about 75% from 1994 to 2003, increasing from about 4

million to around 7 million in 2003. This evolution is due to a sustained economic

growth on the continent and worldwide. Traffic recovery is particularly significant in

some countries. After recent political unrests in Madagascar and Congo, passenger

traffic in main airports grew respectively by 70 and 17 per cent between 2002 and 2003.

The increase of figures in the region is also driven by oil- related activities in Chad and 10 Ässengers Traffic in ASECNA main Airports


28

Equatorial Guinea. The construction of the pipeline between that country and the

oceanic coast through Cameroon has stimulated traffic.

Passenger Traffic by Airport

Figure 2.14: Average Airport Passenger Traffic (2000-2004)

484

500

700

787

1336

0 200 400 600 800 1000 1200 1400 1600

Niamey (Niger)

Ndjamena (Chad)

Nouakchott (Mauritania)

LOME (Togo)

Ouagadougou (Burkina)

Yaounde (Cameroon)

Cotonou (Benin)

Port Genrtil (Gabon)

Malabo (Guinea)

Bamako (Mali)

Pointe Noire (Rep Congo)

Antanarivo (Madagascar)

Brazzaville (Rep Congo)

Douala (Cameroun)

Libreville (Gabon)

Abidjan (Ivory Coast)

Dakar (Senegal)

(Thousand Passengers)


Among the main airports, Dakar airport is the first in the region with more than 1

million passengers per year. It’s has been the fastest growing airport in term of

passenger volume. The important tourism activity in Senegal is the major factor that

explains this performance. The traffic is globally increasing in other airports.

Secondary airports in ASECNA receive insignificant passenger traffic and are often

served by very small aircraft.


29

Domestic passenger traffic

Domestic markets are particularly poorly developed across the region. People tend to

travel by road or rail despite the poor state of the network. Only the elite, and business

men who can afford it, use air travel to move within countries. Only Gabon has a

relatively developed domestic market with more than 340,000 passengers in 2003

(Bergonzi, 2006, P7).

Regional passenger traffic

While regional traffic has significantly increased within the other African regions, it has

stagnated in West and Central Africa from 1994 to 2001.

Political trips, seminars, regional emigration and business travels are the main drivers of

regional traffic. However, the mobility from one country to another remains extremely

difficult. It’s sometimes easier to reach another country within the region through Paris

for instance. On the 276 regional city pairs, only 5 per cent of them have 150 passengers

per day (table below). The busiest city-pair is Abidjan – Dakar.

Daily passenger Number of

city pairs

Percentage (%)

More than 150 14 5

70 - 150 28 10

30 - 70 69 25

10 – 30 69 25

Less than 10 96 35

Table 2.3: Daily passenger traffic between city pairs.

Source: Délia Bergonzi, 2006

The most frequent connections in ASECNA are: Dakar-Bamako, Dakar-Abidjan,

Bamako-Abidjan, Douala-Libreville, and Cotonou - Pointe Noire. They all have more

then 100,000 passengers per year. Dakar and Abidjan are the two destinations with the

highest regional passenger traffic, performing respectively 350000 and 200000

passengers per year (OEDC, 2005). Dakar has 15 direct links with others regional cities

and Abidjan is directly linked to 12 others West African cities. The heaviest traffic

flows are the Gulf of Guinea (Abidjan-Accra-Lagos corridor), then the Dakar/Abidjan

axis.


30

The lack of air links in the Central and Western regions is at a damaging situation with

the presence of a number of landlocked states (e.g. Congo, Central African Republic,

Chad, Mali, Niger), where aviation is needed most.

International Passenger traffic

Almost 50% of passenger traffic (6 million out of 11 in 2003) in western and central

Africa is international. Traffic at major airports in ASECNA is presented in table

below.

2000 2001 2002 2003

Dakar 803.8 863.2 918.3 1005.6

Abidjan 744.6 6448 301.9 3127

Douala 198.8 252.9 246 283.5

Bamako 168.2 132.2 112.1 197.1

Antananarivo 198.2 209.9 98.5 176.1

Libreville 246.4 203.9 198.9 149.6

Malabo 42 64 73,9 100.2

Table 2.4: International traffic at major regional airports (Thousand).

Source: ASECNA

In international traffic, for the West and Central Africa region, and particularly in

ASECNA, the dominant connection is towards Europe.

This traffic can be divided in 3 groups: The ethnic Passenger Group, who has ties with

the former European colonial powers, France mainly, creates a natural emigration of

workers in both directions (South-North, North-South). The Leisure and Tourism

group, concerns high-income people who travel to Europe, America or Asia for reasons

such as shopping, Visits to family and friends. The Business travellers, because of

economic ties with Europe, and oil companies are also important drivers for air traffic

in the region. A large part of the traffic is also due to governmental, non-governmental

and international bodies’ staff.

Traffic towards the Middle East is increasing, mostly due to the attraction of Dubai and

pilgrimage to Mecca. North Africa / West and Central Africa traffic is also increasing


31

due to the dynamism of Maghrebian airlines, which take a large share of the 6th

freedom11 traffic departing from Paris to ASECNA.

There is also a significant traffic between African sub regions and ASECNA, mainly

towards South Africa. Traffic towards the United States of America is carried out

essentially via Europe.

Cargo Traffic

Figure 2.15: Evolution of Cargo traffic (1994-2003)

134

98

0

20

40

60

80

100

120

140

160

180

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

(Year)

(Th

ou

san

d T

on

ne

s)


Freight traffic has regularly increased from 1994 to 2000 due to economic upturn. The

decrease observed since 2001 is explained by a dramatic reduction of cargo traffic at

11The right to carry passengers or cargo from a second country to a third country by stopping in one's

own country.


32

main cargo airports (Pointe Noire and Brazzaville in the republic of Congo). But overall

cargo traffic has increased by nearly 37 per cent since 1994.

2.6 Conclusion

The aim of this chapter was to introduce to ASECNA’s air transport industry, and to

find out its main characteristics. This is what was found.

1. ASECNA region is characterised by under development and extreme poverty

2. Air Transport infrastructure is in a bad state or is largely insufficient and the

substitutes to air transport are poorly developed.

3. The airline industry is very weak, and mostly composed of small aircraft

a. Local companies are facing economic and financial difficulties

b. Operating costs are hit by soaring fuel costs, and low aircraft utilisation

c. Yields and margins are low on the domestic market

d. Most local airlines are very small and very often inefficient

e. The fleets are very old

f. The long haul and medium haul markets are dominated by foreign carriers

g. The domestic market is insignificant

4. Air travel is still constrained

a. On the demand side by low incomes

b. On the supply side by regulations

5. Some changes are being observed

a. Aircraft manufacturers expect a fleet renewal over the next years

b. Liberalization policies are slowly being adopted on the basis of the

Yamoussoukro decision

c. New entrants are expected, even low cost carriers

What do these characteristics mean for air navigation service provision and for

ASECNA?

The poor development of air transport substitutes means air transport is crucial to

ASECNA region and should be among the priorities. In order to develop safely and

orderly, the region’s air transport industry needs a reliable air navigation infrastructure

and an adapted air navigation service provision. Air transport cannot develop without

these conditions.


33

Airlines facing difficulties need to improve their efficiency to mitigate the effects of

high fuel costs. With the very low level of yields on the domestic markets and on some

international routes, and given the ultra competitive environment in a limited number of

profitable routes in ASECNA, it is unlikely that there is significant scope for a recovery

in the yields in the next years. Airlines are going to renew their assaults on costs

according to African Airlines Association (AFRAA). These include flying the shortest

routes, carrying optimum of fuel, cruising at optimum speed, minimizing flights at low

altitude during descend and climb. Therefore ASECNA must deliver enough capacity

and airspace flexibility to its customers

But efficiency also means that ASECNA must deliver a cost effective service

provision.

These airlines’ fleets are often very old. Ageing fleet means they are unable to cope

with technological advancements and automation of security and safety systems.

However the fleet renewal expected by manufacturers means higher speeds, and

increased speed variability in ASECNA’s airspace.

The predominance of foreign carriers in ASECNA means the agency must pay attention

to their requirements as well as those of local airlines.

The liberalisation process and the growth of economies in the region will have a

positive impact on competition and on air travel. ASECNA must anticipate these

mutations, and their foreseeable impact on the air navigation system, and articulate its

strategy to match the other exigencies mentioned above.

34

Chapter 3 : Air Navigation Performance review

The aim of this chapter is to analyse the performance of ASECNA’s air navigation

system, and to find out the current system’s shortcomings. Figure 3.1 shows the

region’s Flight Information Regions (FIRs).

3.1 Introduction

The agency controls an area 1.5 times as large as Europe. The region is characterised by

the presence of large inhospitable areas: Oceans, Deserts, and Forests.

The area is divided into 6 Flight Information Regions (FIRs): Antananarivo,

Brazzaville, Dakar Oceanic, Dakar Terrestrial, Niamey, and N’Djamena1. The airspace

is divided into lower and upper zones. The FIRs encompass Terminal Control Areas

(TMAs) or Upper Control Areas (UTAs) as required by ICAO.

ASECNA ensures the control of air navigation flows, aircraft guidance, the transmission

of technical and traffic messages, airborne information. ASECNA delivers terminal

approach aids for the region’s 25 main airports2, as well as for 76 secondary airports.

This includes approach control, ground aircraft guidance and movements, radio aids,

and fire protection services. The agency also gathers data, forecasts, and it transmits

aviation weather information. Theses services are delivered for en route, terminal

approach and landing phases of flights.

3.2 Airspace organization

3.2.1 Description of ASECNA’s FIRs

Dakar’s FIRs

They are located in western Africa. A large part is constituted of inhospitable desert

areas. It is composed of two parts: oceanic and continental. The area is

1 These cities are respectively the capitals of the following countries: Madagascar, Congo, Senegal, Niger and Chad. The Senegalese FIR is divided into an Oceanic FIR and a terrestrial FIR. 2

Douala, Port Gentil, Mahajanga, Garoua, Malabo, Bamako, Bangui, Ouagadougou, Gao, Brazzaville, Bobo-Diolasso, Niamey, Pointe Noire, Nouakchottt, Dakar, Abidjan, Nouadhibou, N’djamena, Cotonou, Toamasina, Sarh, Libreville, Ivato, Lome.

Chapter 3 Air Navigation Performance review

35

classified Class G and F3 and D airspaces. The lower limit is flight level 245 (FL

245). There are about two dozens Prohibited, restricted and dangerous (P.D.R) zones in

the area. The situation is critical above Ivory Coast where three large PDRs areas are

located next to Abidjan’s TMA.

Dakar’s FIRs are bordered by the Following FIRs: Atlantico SBAO, SAL, Canaries,

Alger, Accra (Ghana) and Niamey (Niger). Sierra Leone, Guinea and Liberia manage

Roberts’ FIR, which is a dismemberment of Dakar’s FIR.

There are one Area Control Centre (ACC) in Dakar and one Flight Information

Centre (FIC) in Abidjan.

N’djamena’s FIR

It covers Chad and partly Cameroon, CAR, and Niger. The Airspace is classified G. The

FIR is bordered by Khartoum’s FIR in Sudan, Kano’s FIR in Nigeria, and Tripoli’s FIR

in Libya. One ACC manages the airspace.

Niamey’s FIR

It is located in Western Africa and largely covers an inhospitable desert area. The

airspace is classified class G. The lateral and vertical limits are equivalent to those of

Dakar’s FIR. The FIR divided in two parts: East and West. It is bordered by Kano in

Nigeria, Alger, Khartoum in Sudan, Tripoli in Libya and N’Djamena in Chad. One

Flight Information Centre controls the airspace.

Brazzaville’s FIR

Brazzaville’s FIR (Congo) occupies a central position, between eastern southern and

western Africa. The land below the airspace is an inhospitable virgin forest. The lower

limit is FL 245. The Bordering FIRs are Kano, N’djamena; Kinshasa and Kisangani in

Democratic Republic of Congo (DRC), Khartoum, and Luanda in Angola. One FIC

manages the airspace.

3 Typically Class F Advisory airspace is designated where activities such as gliding, parachuting, high traffic training areas, and military operations take place and it would be of benefit to aircraft operators to be aware that such activities are taking place there.


36

Antananarivo’s FIR

Antananarivo’s FIR is in the trans-Indian ocean area, interfacing with the Asia pacific

region, where there is high density traffic. The airspace is classified G, and the

horizontal limit is FL 245. The Neighbouring FIRs are Maurice, Seychelles, Durban in

South Africa, and Beira in Mozambique. One FIC manages the region.

3.2.2 Fragmentation

FIRs in ASECNA do not strictly follow the contours of national boundaries, and the

delimitation of these FIRs is generally in line with operational requirements.

Brazzaville’s FIR for example regroups partly or entirely 5 countries: Cameroon,

Congo, Equatorial Guinea, Gabon and a part of the Central African Republic (CAR).

N’djamena’s FIR regroups Northern Cameroon, Chad, Northern CAR, and Eastern

Niger. Niamey’s FIR is composed of Niger’s airspace, Eastern Mali, and Burkina.

However, the neighbouring airspaces are managed by different countries: as said earlier,

Sierra Leone, Guinea, and Liberia jointly control their airspaces. Ghana manages its

airspace and that of Benin, Sao Tome and Principe and Togo from Accra’s FIR. Cape

Verde has an extensive oceanic airspace called Sal FIR. Nigeria’s national airspace is

composed of two FIRs: Kano in the North and Lagos in the South. Algeria, Morocco,

Libya, Sudan, the DRC and South Africa also manage their own airspace separately.

Aircraft that fly from one airspace to another have to switch to the local frequency.

This goes along side with varying requirements and procedures from region to region,

and proliferation of ATC systems and technologies according to national and regional

considerations.

That fragmentation is an important cause of inefficiency, in term of cost-effectiveness

and productivity. It contributes to the multiplication of fixed assets and costs, as well as

to higher coordination and transaction costs:

1. Duplication of Air Navigation Service Providers

2. Duplication of Air Traffic Service Units (Area Control Centres, Approach Control

Units)

3. Duplication of ATM Systems and Interfaces

4. Duplication of CNS infrastructure

5. Multiplication of Regulators


37

Figure 3.1: ASECNA’S FIRs


38

3.3 TrafficFigure 3.2: Number of flights from 1993 to 2003

218 209

354 774

0

50 000

100 000

150 000

200 000

250 000

300 000

350 000

400 000

1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

(Year)

(Nu

mb

er o

f M

ovem

ents

)

Source: ASECNA, annual reports (1994 - 2003)

As defined by ICAO, air traffic is the number of aircraft flights operated in a given

airspace. In 2003, more than 354774 flights were operated in ASECNA, which

represents a 63 per cent increase comparing to 1993. This represents 646 aircraft

movements every day. The growth has been constant, at an average yearly rate of

5.3 per cent (Figure 3.2).

3.3.1 Airport Activity

During the last ten years, traffic in the region’s airports has continuously grown. The

number of aircraft movements has increased by 5.3 per cent per year on average. In

2003, international and local airlines’ activity4 has increased, mainly driven by a

noticeable economic recovery in the region, with a 3.1 per cent average growth

(ASECNA, 2003) and between 4 and 5 per cent in 2004.

4 Air Madagascar, Air Senegal International, Air Mauritanie, Nouvelle Air Ivoire, Air France, Air Burkina SA, Societe de Transport Aerien Malien, National Airways Gabon, UTAGE, Afriqyah Airways, Afric Aviation, Air Excellence, West African Airlines.


39

Figure 3.3: Number of aircraft movements at 15 key airports

Source ASECNA, annual report (2003)

Libreville is the busiest airport in the region in term of movements as Figure 3.3 shows

it. Dakar and Douala are respectively second and third.

Runway Capacity

Runway capacity is often the limiting factor for airport capacity. The queuing theory

indicates that smoother arrival flows allow increased throughput and reduced delay. It

allows the trade off between capacity and delay to be improved. To maximise the use of

runway capacity, it is essential to accurately guide aircraft at the final approach fix

(FAF).

There were about 18.66 aircraft movements per hour in ASECNA’s airports from

2000 to 2003. Libreville’s airport had 3.37 movements per hour, followed by Dakar and

Douala, respectively 1.99 and 1.95. Six international airports had less than one

movement per hour. Of course, these average figures do not take into account the

variation of traffic. However, even during busy periods, the busiest platforms, like

Libreville or Dakar hardly reach 9 movements per hour. The runway occupancy remains

at very low levels. This clearly indicates that runway capacity is not an issue of

concern in the region as it is in European or North American airports.


40

3.3.2 En route Traffic

The main Airstreams

The statistics from 2001 to 2003 indicate that the segmentation of en route traffic is

stable, and is mainly composed of intra Africa activities, and flows between Africa and

European countries (Table 3.1).

The heaviest traffic flows are the Gulf of Guinea (Abidjan-Accra-Lagos corridor),

followed by the Dakar/Abidjan axis and the North-South traffic flow. The East-West

traffic is less dense. The traffic between European countries and the region which

represents 25 per cent of all activities is driven by Air France-KLM. The activity is less

important towards other parts of the world: Traffic towards the middle is low.

Exchanges with America are relatively poor. However, routes between that part of the

world and Europe go through ASECNA’s FIRs (Figure 3.4).

1999 2000 2001 2002 2003

Intra-Africa 175693 199172 224374 225398 236812

Europe-Africa 80628 82568 80492 78081 84690

Europe-America 21012 22257 23651 22175 21843

Middle east-Africa 3579 3927 3982 4609 4838

America-Africa 3748 4266 4894 4460 4788

Divers 23368 2565 2671 2969 1803

Total 287008 314755 340064 337692 354774

Table 3.1: The main Airstreams in ASECNA

2001 2002 2003 Average

Antananarivo 35893 28157 35086 33045

Abidjan SIV 24339 23312 26861 24837

Niamey 31825 32694 34703 33074

N’Djamena 23030 24588 25747 24455

Brazzaville 59987 62385 63811 62061

Dakar 57887 57725 58889 58167

Table 3.2: Traffic by FIR


41

Figure 3.4: Areas of Routing.

Source: ATNS

In Dakar’s FIRs, major traffic flows are driven by airstreams from the Americas and

Europe. The FIRS are involved in air activities between Europe and South America, and

in the Atlantic Ocean interface between the North Atlantic, Africa, and South America

regions. Input traffic also comes from the Coastal routes over the Gulf of Guinea and

from Trans-Sahelian operations (Figure 3.4). Dakar’s FIRs accounted for about 25 per

cent of all ASECNA’s traffic on average from 2001 to 2003.

Niamey’s FIR is mainly involved in Trans-Saharan traffic flow and Europe to southern

Africa routes. These routes receive an important traffic due to the activity generated by

South Africa mainly. Fourteen per cent of the traffic went through Niamey during the

period considered.

N’djamena’s FIR’s activity is mainly constituted of over flights from southern, eastern

and central Africa. The area accounted for about 10 per cent of activities during the

period. Traffic density is low.

FIRs Niamey & N’Djamena

FIR Brazzaville

FIR Dakar


42

Brazzaville accounted for 27 per cent of flights during the period. A large part of traffic

in Brazzaville’s FIR comes from South Africa.

En route Capacity5

Flights

per Day

Flights

per Hour

Percentage

(%)

Number

of ATCO6

Traffic Density

Dakar 159 6.6 24 42 Low

N’Djamena 67 2.8 10 40 Low

Niamey 91 3.8 14 33 Low

Brazzaville 170 7.1 27 23 Low

Antananarivo 91 3.8 14.5 27 Low

Abidjan 68 2.8 10.5 26 Low

ASECNA 646 26.9 100 391 Low

Eurocontrol 22920 955 100 NA Very High

Table 3.3: Average traffic density from 2001 to 2003

Sources: ASECNA, internal document (appendix 10), and annual reports (2001-2003). Eurocontrol, Performance Review Reports (2001-2004)

Dakar’s ACC and Abidjan’s FIC manage on average 227 flights per day, which is

equivalent to 9.4 movements per Hour and 1 movement every 7 minutes. But this does

not take into account the time and period distribution of flights.

Brazzaville is the second busiest FIR as the FIC manages about 170 flights per day,

which represents 7.1 movements per hour and one every nine minutes.

About 67 flights are managed by N’djamena’s ACC each day, representing 2.8 flights

per hour and about one flight every 21 minutes,

In Antananarivo, on average, 91 aircraft movements are managed every day, 3.8 flights

per hour, and 1 every 17 minutes.

Traffic density in ASECNA is very low when compared to the level of traffic in

Europe.

5 The average number of flight per day and per are obtained by dividing the number of flights per year by 365. 6 Air Traffic Controllers (2004 figures).


43

Controllers’ Productivity

Productivity is defined as the average number of aircraft controlled per hour per air

Traffic Controller (ATCO). It is calculated by dividing the total number of aircraft

movements in the FIRs by the total number of ATCOs. A better way to measure

productivity would have been to measure the number of flight-hours controlled per

controller-hour in duty, but the data were not available. Eurocontrol’s figure is derived

from the average flight-hours controlled per ATCO-Hour in duty, and annual number of

IFR flights and the number of flight-hours. The average flight-hours controlled per

controller-hour in duty was 0.8 (Eurocontrol). There were 12.2 million flight-hours and

8.9 million IFR flights in Europe in 2004. This means 1.37 Hours per flight on average.

Therefore, each controller controls 0.8 divided by 1.37 (0.583) flight per hour.

Figure 3.5: Average flights controlled per hour and per controller in ACCs

ATCOs’ productivity in ASECNA varies from one ACC to another. The busiest ATCOs

are those of Dakar and Brazzaville. Each air traffic controller controls on average 0.1

flight per hour in ASECNA, whereas the equivalent figure is about 0.6, which is 6 times

higher.

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Antana

nariv

o

Abidjan

SIV

Niamey

N’Djam

ena

Brazza

ville

Dakar

ASECNA

Euroc

ontro

l

(Control Centres)


44

3.4 Delays

Air transport delays are given by the scheduled departure and arrival times. Delays can

be broken down by phase of flight.

When traffic demand is anticipated to be higher than the actual ATM capacity in en-

route control centers, or at the airports, Air Traffic Units may apply Air traffic Flow

Management (ATFM) regulations. This means that airplanes subject to that regulation

are held at departure airports. The AFTM delay is then allocated to the busiest ATC

unit.

In ASECNA, delays are almost never the result of Air traffic services. Except during bad

weather periods, the totality of delays is due to airlines’ preflight operations. There is no

ATFM unit like in Europe for instance (Ngoué Celestin, Head of Air Navigation,

ASECNA). Many airlines managers confirmed that reality, which is also corroborated

by the availability of sufficient airspace capacity.

3.5 Impact of future trends

3.5.1 Prospects

All aircraft manufacturers (Boeing, Airbus...) or airlines organisations (IATA, ICAO)

use roughly the same methodology for assessing long term traffic forecast. It is based on

the assumption that long-term demand for air travel is driven by economic

developments, notably the growth of world and regional income levels.


45

Figure 3.6: Projected traffic growth over the next decade

4

4,2

4,4

4,6

4,8

5

5,2

Africa

- PR

C

Africa

- M

iddle Eas

t

Africa

- USA

Africa

- W

este

rn E

urop

e

Africa

- Can

ada

Africa

- Ja

pan

Africa

- CIS

Africa

- Sou

th A

mer

ica

Africa

- Aus

tralia

/NZ

Africa

- Eas

tern

Eur

ope

Per

cent

age

Source: Boeing, Airbus, ASECNA, IATA.

Western and Central Africa countries economies are expected to grow at an average

pace of 4.5 per cent during the next decade according to African bank of development

(BAD). It can be assumed that air travel and air traffic are going to follow that pace.

Depending on the industry’s estimate taken into account, air traffic will grow in Africa

between 5 and 7 per cent over the next 15 years. ASECNA expects even a 7 per cent

growth. However, Africa’s overall share of traffic is expected to decrease to 2 per cent

instead of the current of 3 per cent.

The average growth rate for the next 15 years is 5 per cent yearly. This means there will

be about 737550 flights in ASECNA by 2020; traffic will have doubled.

3.5.2 Impact on Runway Capacity

With the projected growth rate, there would be about 41 landings or take-off each hour

in all ASECNA area airports. If the relative importance between airports does not

change, Libreville will handle around 7 movements per hour followed by Dakar and

Douala with respectively with 4.7 and 4.3 operations per hour on average (Figure 3.7).


46

Comparatively, the busiest hour at London Heathrow in 1999 saw 93 movements per

hour on the airport's two runways.

Figure 3.7: Projected Runway Occupancy in main airports (flights per hour)

0

1

2

3

4

5

6

7

8

Librev

ille

Dakar

Douala

Mala

bo

Abidja

n

Port G

entil

Bamak

o

Antana

nariv

o

Coton

ouLom

é

Nouak

chott

Ouaga

doug

ou

Niamey

Toam

asina

N'djam

ena

Source: ASECNA, compiled from annual report 2003.

3.5.3 Impact on en route Capacity

Flights per

Day

Flights Per

Hour

Percentage

of Total

Number of

ATCOs

Traffic

Density

Dakar 332 13.8 24 104 Low

N’djamena 140 5.8 10 60 Low

Niamey 189 7.9 14 76 Low

Brazzaville 354 14.7 27 76 Low

Antananarivo 189 7.8 14.5 72 Low

Abidjan 141 5.9 10.5 35 Low

ASECNA 1343 56 100 699 Low

Table 3.4: Average traffic density by 2015


47

ASECNA’s FIRs would receive about 1342 flights per day (56 per hour). It is

insignificant when compared to Europe’s records, 30,000 flights per day, and one

operation handled every 3 seconds (CFMU, 2005).

Controllers’ productivity

Figure 3.8: Projected Controllers’ productivity in 2015

0.0

0.1

0.2

0.3

0.4

0.5

0.6

Antana

nariv

o

Abidjan

SIV

Niamey

N’Djam

ena

Brazza

ville

Dakar

ASECNA

Controllers’ productivity would remain lower than European controllers’ 2003 record.

3.6 Traffic complexity

A good analysis would require additional data such as flow structure (horizontal

intersection per miles), traffic mix (standard deviation of aircraft speed), and traffic

evolution (number of flight level changes per miles, horizontal intersection per miles).

These information were not available. However, traffic density is low and will remain

so in ASECNA. All the busiest routes are north and south bound. These routes generate

the highest levels of passenger traffic. They link major local airports to Europe.

Domestic traffic is inexistent and East-West routes are not really busy, except the golf

of Guinea corridor, and routes between certain capital cities. But,


48

seasonally, during the pilgrimage period, routes towards Saudi Arabia (East-West)

cross major North-South traffic flows, and create convergent points generating traffic

complexity (Samake Wodiaba, ASECNA). The projected growth suggests that traffic

complexity is going to increase as east-west flows are going to grow faster than north-

south operations.

3.7 Safety

Safety is the prime objective of ATM. In ASECNA’s safety reports, events are

composed of 6 elements: Air proximities (Airprox), users’ claims, Aviation security,

Bird strikes and Accidents. The period considered goes from 1999 to 2004. 2004

figures in the chart below are only partial data.

3.7.1 Air Proximities

An airprox is a situation in which, in the opinion of a pilot or a controller, the distance

between aircraft as well as their relative positions and speed have been such that the

safety of the aircraft involved was or may have been compromised. The number of Air

proximities is constantly high with regard to the low traffic density in ASECNA.

Figure 3.9: Evolution of Air proximities

0

5

10

15

20

25

30

250 275 300 325 350

Number of flights (000)

Air

pro

xim

ities



49

The situation seems to improve with the increase of traffic (Correlation between the

number of air proximities and traffic figures is equal to “-0.8”). This may reflect a better

surveillance and communication capability in the region. The number of safety-related

events seems to vary significantly between ASECNA’s regions. Central Africa

concentrated 50% of total events during the year 2004. It is not clear whether or not this

is due to differences in reporting practices, or the concentration of traffic on certain

corridors not properly furnished with surveillance means.

Figure 3.10: Evolution of incidents during the last six years

Source: ASECNA, (unpublished document).

3.7.2 Users’ claims

Users’ claims accounted for about 20 per cent of reported events. These are made by

airspace users. ASECNA statistics do not tell if every claim is investigated. It’s likely

that many are purely ignored, due to the lack of mean to conduct an efficient

investigation.

3.7.3 Birdstrikes

Birdstrikes are very frequent in ASECNA. 28 per cent of incidents during the period

were related to aircraft engines “swallowing” birds, very often at the vicinity of airports.


50

Accidents reported are not always related to air navigation events. They nearly

constitute 26 per cent of events. Most of them occur on the ground, at major or

secondary airports (runway incursions). The figures presented on Figure 3.10 are

probably optimistic as many accidents or incidents are not reported at all, particularly at

remote airports.

3.7.4 Safety Review System

Four features are essentials to make incident reporting useful for accident prevention

and safety management:

1 A reliable, timely and large enough information flow

2 Data analysis

3 Severity Classification

4 Exposure of the data

For every incident assessed ASECNA determines one or more causal factors. These tell

the agency why events started in each instance and signposts the lessons to emerge.

ASECNA has safety committees that perform that job. It is self evident that attention

paid to the cause of an accident is worthwhile because it is likely to deliver and promote

better prevention and to establish the responsibilities. ASECNA is often responsible for

safety related events. But the agency does not seem to systematically investigate

incidents, and information on safety data is hardly available. When it is, it’s not

adequately classified.

3.8 Efficiency

3.8.1 Flight efficiency

Flight efficiency is the next key performance Area considered in this study. Flight

efficiency has implications for fuel burn, pollution and its environmental impact. Flight

efficiency has horizontal and vertical components, which can be split into en-route and

terminal flight phases. The report focuses on en-route flights. Insufficient information is

currently available to address vertical flights efficiency. Moreover, it has not been


51

possible to study the most “constraining points7” in ASECNA.The safest routes in

ASECNA are controlled routes. These routes are equipped with ground based

navigation aids pilots have to follow. That compulsory process increases routes length

and reduces flight efficiency. Major routes link South Africa to Western Europe.

Aircraft have to go through Brazzaville, Niamey or N’Djamena. To go from Douala

(DLA, Cameroon) to Dakar (DKR, Senegal), pilots have to use the following routes:

1. UB 737 from Douala to Sao Tome and Principe (TMS)

2. UA 400 from Principe to Abidjan (ABJ)

3. UR 979 from Abidjan to Dakar, or UB 600 through Monrovia (Liberia) and

Conakry (Bissau) (Figure 3.11).

Figure 3.11: Flight Paths between Douala and Dakar.

(In Red: Direct path. In dash Blue: Conventional path)

3.8.2 Fuel Efficiency

The fuel efficiency of an airline is determined by many factors. Some are directly under

airlines control, others are not. The later are related to market, technology, and

infrastructure.

7 The most constraining point is the point along a trajectory that contributes the most to the additional distance. This point generates additional costs.


52

Figure 3.12: The different phases of a flight

Source: Mitre Corporation

To illustrate this requirement of fuel efficiency, the following is an estimation of extra

costs related to flight inefficiency on the route Douala (DLA) - Dakar (DKR). Only the

cruise portion of the flight is considered.

The aircraft operated is a B737-3008. Its seat capacity is 140 and range is 4320 Km. The

range is chosen such that the effect of load factor that have an influence when the

aircraft is operated at the limits of range can be neglected. The fuel consumption for a

B737-300 is estimated at 26 g/seat.km (Japan Airlines, 2005). Most of the aircraft

weight is then considered to be fuel and hull. We assume that the flight altitude on the

cruise portion is 32800 feet, and the weather condition are ideal, and the traffic is not

complex and does not generate holding patterns.

The cruise speed is supposed to be constant at 815 km/h. The descent starts about 100

km from each airport. The Descent phases of flight (Vertical profile) and the taxi times

are not considered, although we already know that efficient approach operations allow

fuel saving. The Fuel Density is 800g/litre; and the current spot fuel cost around the

world is about US$1.80 / US gallons.

8 Details from (Air Charter International, 2005)


53

Conventional Flight (Following ground Navigation aids)

Distance Flown during the horizontal profile: 3640 Km – 2*1009 = 3440 Km

Seat.Km: 512560

Fuel Burn: 13327 Kg, which is equivalent to 16659 litres, and 4401 US gallons10

Fuel cost: 7922 US$

Direct Flight

Distance Flown during the horizontal profile: 3211 Km – 2*100 = 3011 Km

Seat.Km: 448639

Fuel Burn: 11665 Kg, which is equivalent to 14582 litres, and 3853 US gallons

Fuel cost: 6936 US$

Comments

The difference in term of Fuel consumption is about 2077 litres, 12.5 per cent. The

savings on the horizontal profile only would be about 986 US$. For 6 legs per week, the

total reduction in fuel cost is 5916 US$. Assuming continuous operations without

disruptions during the whole year, the savings would be 307,632 US$ on that single

route. But a large part of fuel inefficiency also lies on the problem of aircraft age. Old

aircraft generally consume more fuel than newly built ones as shown in chapter 2.

Flying the direct route would also free 164 hours during the year that a company could

use to improve aircraft utilization. But this would depend on the slot structure at the

served airports.

Beyond the improved aircraft economics, the positive impact on environment is also

substantial. On this case, the reduction in Carbon Dioxide (CO2) emission would be

about 1815 tonnes11 during the year.

9 We assume that that the descent phase begins 100 Km before the airport10 1 USGAL = 3.785412 Litres11 1 Kg of fuel burn produces 3.5 Kg of CO2 (Japan Airlines, )


54

3.9 Cost effectiveness

3.9.1 Navigation charges

Figure 3.13: Evolution of Air Navigation charges (Unit Rate) in ASECNA (Euros)

0

20

40

60

80

100

120

1999 2000 2001 2004 2005 2006

DOMESTIC FLIGHTS REGIONAL FLIGHTS

INTERNATIONAL FLIGHTS

Source: ASECNA

ASECNA’s current charging policy is as follows: Charge for use of en-route facilities

and services managed by the agency are payable whatever are the conditions in which

the flight is accomplished (IFR or VFR) and whatever are the departure and the

destination aerodrome. Charging varies depending on the nature of the flight (national,

regional, international). For regional or domestic flights, users pay a fixed price. For

international flights, users pay a price that varies with the weight of the aircraft and the

distance flown.

From 1999 to 2005, charges for international flights increased by 40 per cent. But, the

price is stabilized since 2004 thanks to an agreement with IATA. The price of regional

flights is being reduced since 2001, and the price of domestic flights is stable.


55

3.9.2 Air Navigation Services Costs

Evolution of Costs12

Figure 3.14: Personnel, ANS and Transport costs from 1996 to 2003

0%

10%

20%30%40%

50%60%

70%80%

90%100%

1996 1997 1998 1999 2002 2003

Costs of Personnel Cost of ANS Other Costs Cost of Transport

Source: ASECNA, annual reports (1996 – 2003)

The costs of personnel represent more half of total costs. They have increased

continuously since 1996. ANS and personnel costs accounted for about 80 per cent of

expenses in 2003, and their share is stable. Transports costs are stable.

12 ANS costs include supplies and materials. ANS personnel costs are included in personnel costs


56

Figure 3.15: Evolution of the average cost per flight from 1996 to 2003 (Euros)

220

230

240

250

260

270

280

290

300

1996 1997 1998 1999 2002 2003

Source: Compiled from ASECNA’s annual reports (1996 – 2003)

The average unit cost is increasing. The cost per flight was about 288 Euros in 2003.

Unit cost has increased by 18 per cent on average from 1998 to 2003, which represents

an annual increase of 3.6 per cent. On average, ASECNA’s unit cost is the lowest as

shown on the table below. But that figure does not reflect the exact reality, as domestic

and regional airlines only paid a fixed price, whereas international flights are much

more expensive. It means international airlines pay a much higher unit cost per flight.

Nearly 80 per cent of these charges are paid by major western and international

airlines (ASECNA, 2003).

ASECNA 28813

Eurocontrol 591

FAA 35114

Table 3.5: Average ANS cost per flight (Euros)

in Europe ASECNA and the USA (2003)

The totality of charges above is passed to users. En route revenues have continuously

increased since 1996 by 11.6 per cent on average per year (Figure 3.16)

13 ASECNA’s figure includes all personnel costs. ANS personnel costs were not available separately14 357 dollars

Trend Line


57

Figure 3.16: Evolution of En route revenues from 1996 to 2003 (Million Euros)

020406080

100120140160180

1996 1997 1998 1999 2002 2003


3.10 Cooperation

ASECNA cannot deliver a satisfactory service without interacting with other air

navigation authorities in the region. The agency encircles large blocks of airspaces like

Nigeria, and Ghana as described in chapter 2. It also shares common airspace borders

with huge entities such as the Canaries, SADC, Algeria, Libya, Sudan and others.

Nigeria has deep infrastructural deficiencies, which gave rise to the blacklisting of their

airspace by some international organizations: Obsolete navigation and landing aids as

well a collapsed surveillance system. The navigation and landing aids are not

functional most of the time, the six terminal approach radar stations are broken down

and air traffic control service are not provided to some en-route traffic (Nigeria

Airspace Management, 2005).


58

Figure 3.17: Regional Fragmentation of ATM sectors

Source: CANSO

Clearly cooperation is needed between all these states to develop a seamless and cost

efficient ATM system at a regional level. Harmonisation provides much of the answer.

The region needs a plan to achieve common standards procedures and technology, and

ensure interoperability between various systems. Multi-national cooperation among

provider States and users are essential to minimize investment costs, ensure

compatibility and avoid duplication of effort. Moreover, by agreeing on common

technologies, ANSPs and state would increase their bargaining power when buying new

systems.

Trans-national bodies provide coordination (ICAO’s AFI CNS/ATM regional Sub-

Groups). But still, there are challenges in bringing the regulators and the governments to

commit to an efficient air navigation system. African states, airspace users, ATC service

providers, and equipments suppliers do not have the same motivations and benefits.

Moreover, “different regulatory models, different regulatory requirements undermine

moves towards harmonisation. Sovereignty issues, slowness in administrative and

legislations procedures, differences in time frames, often contribute to delay advances

in the system” (Yoro Amadou Diallo, ASECNA).


59

3.11 Training

Traffic is growing and complexity is increasing. ASECNA needs to go hand in hand

with changes. In Africa, many air ANSPs have unfortunately tended to invest in equipment but

have hardly paid attention to the training needs of the human beings who must operate it.

ICAO has established minimum standards for approved ATC training and has approved

institutions in several African countries like in ASECNA. ASECNA trains part of its

controllers in its own institutions it manages in Niamey, Niger.

However, the total capacity of these institutions is less than 30 per cent of the total

training requirements of Africa. Many African ANSPs are compelled to train their

students in foreign ATC training institutions. Since there is a global shortage of air

traffic controllers, most ATC training institutes outside Africa are fully booked to train

their own nationals to meet local needs. In addition, training fees keep increasing as a

result of growing demand.

3.12 Financing

Figure 3.18: Financial results from 1994 to 2003

0

20

40

60

80

100

120

140

160

180

1994 1995 1996 1997 1998 1999 2000 2001 2003

0

20

40

60

80

100

120

140

160

180

Operating revenue Operating Expenses

Operating Result Operating ratio


MillionEuros

%


60

One of the major concerns for management of air navigation systems is the financial

requirements for developing countries like in ASECNA. “Member states do not always

have the means to finance air navigation infrastructure improvement as they have other

priorities, such as health, education, poverty reduction” (M. Marafat, ASECNA).

A survey conducted by ICAO's technical cooperation bureau estimated that 97 per cent

of the least developed countries and 83 per cent of the developing states require

technical and financial assistance to improve their air navigation systems (ICAO-Rio

Conference 1998).

ASECNA regularly posts good financial results. Its operating revenue almost doubled

from 1996 to 2003, and its operating ratio is constantly very high (144 per cent on

average during the last 10 years).

3.13 CNS and Aviation Weather Management issues

3.13.1 Shortcomings of conventional systems used by ASECNA

It is recognised that current air navigation systems suffers from technical, operational

and procedural shortcomings, which has serious economic impact on air transport

community. These shortcomings amount to the following factors.

Communications

Despite recent improvements in ATC such as new radar scopes, voice switching

systems, today’s air traffic control primarily relies on a single tool to actually separate

aircraft: a highly congested voice radio frequency. The current ATC system uses

voice communications between air traffic controllers and pilots to relay instructions and

other information critical to operate safely. These communications are necessary to

support coordination of aircraft movements in all phases of flight, to ensure aircraft

separation, transmit advisories and clearances, and to provide aviation weather services.

Skies over international airports are made more dangerous by the lack of standardised

terminology or proficiency levels in English for flight crews and air traffic controllers.

Language confusion is a frequent cause of pilot error. Although English was made the


61

common language of world aviation in 1951, miscommunication and crashes in which

communication was a contributing factor are common. These include ambiguities and

misnomers. Phrases are not derivations of a master plan as they should be. The inability

of English to express specific instructions to pilots without confusion disqualifies it as a

language for permanent use by aviation (Kent Jones, 2005).

One speaker at a time: The voice communications link between controllers and pilots

is similar to a conference call, with the controller and all pilots flying within an airspace

talking over the same channel.

This is very similar to ATC voice communications in congested airspaces. It is not

unusual for pilots to key their microphone and accidentally "step on" the

communication of other pilots or a controller. These are time consuming routine

messages. They waste more time on the ATC voice channel as repeated attempts to

communicate are made. This problem will only get worse as air traffic continues to

increase. Each voice radio exchange takes a certain amount of time for the originator to

transmit and the receiver to respond, and there is a point of saturation where a controller

physically cannot fit in any additional voice radio communications. At this point, no

additional aircraft can be handled within the controller's assigned airspace (Mitre-Caasd,

2005).

Navigation

Fixed airways: Airlines are currently required to plan their flights on the basis of a

fixed route structure, which is largely defined by ground-based navigation aids. The

fixed point-to-point route segments, indirect routings, which rely mostly on ground

based navigation aids, are not the most efficient way of getting from one place to

another. That limits enroute capacity and reduces efficiency. But it has been necessary

because of the limitations in air traffic control technology (Department of Foreign

Affairs and Trade, 2005).

Range Limitations:The current system of land-based navigation requires to over-flight

certain VOR sites, intersections and one-way airways to organize the flow. This means,


62

as mentioned previously, that airways depend on the geographic location of navigation

aids. Moreover, airways are like a highway system on the ground. Like the later, at

intersections with crossing traffic, some aircraft can get stuck waiting for the “light to

change” (holding). By creating airways independent of the geographic location of a

ground navigation aid, those airways can be spread out. Spreading the traffic out

increases capacity and safety (Zelechosky et Al, 2005).

Large amount of airspace between each aircraft: Conventional air guidance

systems on board the aircraft and are not precise enough. Therefore, Control centres

have to maintain a 15 minutes horizontal separation between aircraft. As a result, there

is a large amount of space is lost.

Surveillance

Basically, the surveillance systems presently in use can be divided into two main types:

dependent surveillance and independent surveillance. In dependent surveillance

systems, aircraft position is determined on board and then transmitted to ATC. The

current voice position reporting is a dependent surveillance system in which the

position of the aircraft is determined from on-board navigation equipments and then

conveyed by the pilot to ATC by radiotelephony. Independent surveillance is a system

which measures aircraft position from the ground.

Ground-based separation assurance: The Separation ensures that an aircraft

maintains a safe distance from other aircraft, terrain, obstacles. Capabilities include

ground based separation functions on the airport surface and in the terminal, en route,

and oceanic domains. New on-board systems such as the Traffic Alert and Collision

Avoidance System (TCAS) can allow the pilot to execute an evasive manoeuvre. But all

aircraft are not fitted with such systems, especially, local small airlines in regions like

ASECNA area.

Primary Surveillance Radar (PSR): PSR radars operate by radiating electromagnetic

energy and detecting the presence and the character of echoes returned from reflecting

objects. It is an active device using its own controlled illumination for target detection

based on reflected radar energy. However, detection depends on radar cross-section and

line-of-sight and it requires high energy transmission results in costly implementation


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on ground. The fact that the antennas rotate limits the detection to the beam direction

and suppresses targets within the cone of silence. Moreover, PSRs offer no possibility

to identify the target: It only allows detection. At last, it is very sensitive against

reflections (clutter, sea, weather), and detection depends on a sufficient signal to- noise

ratio.

Secondary Surveillance Radar (SSR): SSR radars transmit coded interrogations to

receive coded data from any aircraft equipped with a transponder. It provides a two-way

data link on separate interrogation and reply frequencies. Replies contain either positive

identification (1 of 4096) or aircraft pressure altitude. But they have similar drawback

to PSRs’ ones. Even the identification is only limited to 4096 codes, and they are

subject to FRUIT (False Replies from Interfering Transmissions), Garble (reply overlap

at the ground receiver) and over-interrogation (due to a high number of interrogators).

All these reduce the probability of detection.

Airport Operations

Airport movements severely restricted during low visibility: During good visibility

conditions the landing capacity of major airports is mainly limited by the final approach

separation minima defined by ICAO, and that sequences accuracy and runway

occupancy times. When the visibility deteriorates and becomes less than a certain limit

the use of landing runways is stopped because pilots cannot maintain visual separation

in case of simultaneous missed approaches for instance (Hans Offerman, 2005).

Moreover, during these conditions, separation requirements between aircraft increase to

avoid runway incursions. All this results into decreased “airport capacity” and increased

controllers’ workload.

Aeronautical information and weather services (AIS)

Disparate formats and standards: The objective of AIS is to ensure the flow of

information necessary for safety, regularity and efficiency of flight operations. In that

respect, each state is required under international agreements to provide this service and


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is responsible for the information provided15. It is provided to pilots in face-to-face

briefings at the aerodrome AIS unit, or in flight, through air traffic control.

Communication of the latest information to users is effected through the aeronautical

fixed telecommunication network (AFTN) in the form of notices to airmen (NOTAM).

This information is however not already available in real time due to technical

limitations.

3.13.2 ASECNA’s systems’ performance

VHF coverage

ASECNA area is 16,000,000 Square kilometres large. A VOR Beacon range is 240 KM.

therefore the number of VORs necessary to cover the entire area is equal to 88.46. This

means that to cover its entire airspace with VHF capability and makes it available for

flights, 89 VORs are necessary. In 2003, ASECNA had only 60 in operation, which

represents 68 per cent coverage of the area. But VHF technics that use VSAT (Very

Small Aperture Terminal) and SATCOM technologies to extend the VHF coverage in

inhospitable areas have improved the situation. Many VSAT have been installed in the

region, and there are other projects under implementation. The most frequently used

means for Aeronautical Mobile Service (AMS - air/ground and air/air communications)

is the HF, which has an extended range but presents drawbacks and the VHF. These

technologies operate well on the whole in ASECNA. But on the one hand, the VHF is

increasingly used and has considerably improved; both from the point of view of quality

and availability (Table 3.6 below), and on the other hand, the HF is still the only

available mean in several sectors, like in the oceanic FIR, and large parts of the Sahara

desert and forests.

The Aeronautical Fixed Service (AFS), which ensures the transmission of flight plans

and other aeronautical messages between specific fixed points, operates fairly well,

15 Conventional aeronautical information services consist on the provision of hardcopy documents in the form of the Integrated Aeronautical Information Package (IAP), which contains information for the entire territory and also areas outside the territory for which a State is responsible for the provision of air traffic services. The information must be provided in a suitable form and must be of high quality, be timely and include, as necessary, aeronautical information of other States. In addition, pre-flight and in-flight information services must be provided.


65

especially at main airports. The Fixed Service is often backed up, or replaced by the

SITA16 network, a private network generally used by airlines.

Equipments 2000 2001 2002 2003 Average (%)

Navigation Aids 96.4 96.8 96.9 93.6 95.9

Terrestrial station 96.0 98.2 98.1 98.2 97.6

Communication

Equipments

91.1 94.4 95.8 97.2 94.6

MET Equipments 91.0 92.3 94.5 93.3 92.8

Energy

Equipments

96.0 96.2 98.1 98.1 97.1

Average 93.6 95.4 95.2 95.9 95.0

Table 3.6: Equipments availability in 2003.

Source: ASECNA, annual report, 2003

Transmission speed

The requirement of a minimum modulation rate of 1200 bauds is not met by some main

circuits. The following AFTN main circuits do not meet this requirement: Niamey

/Addis Abeba, Dakar/Casablanca. Tributary circuits connected to the main centres of

Brazzaville, Dakar, Johannesburg and Niamey have been upgraded to higher

transmission speeds, while the outgoing main circuits are operated still at 50 baud.

Use of analogue technology

The level of digitalization is rather low: only 29 out of 65 circuits (44.3%) are digital

circuits in the region, which limits the bandwidth and the data processing capability.

Statistics show that the requirements of 5 minutes maximum for high priority messages

and 10 minutes maximum for other messages are not met most of the time.

Navigation

The main navigational aids in the region operate fairly well. However, many of them

have reached their age limit, especially the Instrument Landing Systems. VORs coupled

or not with DMEs, are implemented in all international aerodromes and are generally

16 Société internationale des télécommunications aéronautiques


66

operational. All these ground facilities work towards providing safe navigation in the

ASECNA. Navigation aids equipments’ availability rate (95.9 on average) is below

international standards (Table 3.6). Secondary airports do not often have Landing aids,

and some international airports, like in Equatorial Guinea, do not posses such systems.

Surveillance

The use of radar is very rare in ASECNA area and in West Africa in general. The

explanation given is that ICAO recommends that states should use radar only if the

situation really warrants it. If this is taken as a rule, it would apply to the Gulf of Guinea

States (Ivory Coast mainly). A secondary radar system has been undergoing tests in

Abidjan for the past few years. Its official commissioning has been delayed because of a

problem between the government and ASECNA. It has nonetheless proven very useful.

As an example, recently, a few hours after a recent takeoff from Accra, an aircraft

heading west realized that its navigation instruments were no longer functioning. It

therefore decided to land in Accra, its point of departure. Soon after, it was seen on the

Abidjan radar screens heading north. The Ivorian controllers were able to guide it safely

to its final destination.


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FIRs

ASECNA

Routes Length

in the FIR

(NM)

Controlled routes

Length (NM)

Percentage of

Controlled routes (%)

ANTANANARIVO 9554 5954 62

BRAZAVILLE 11467 8329 73

DAKAR TERRESTRIAL 17471 13826 79

DAKAR OCEANIC 3973 3973 100

NIAMEY 11315 10270 91

NDJAMENA 8349 8163 97.7

Total length 62129 50515 81.3

Table 3.7: Air circulation control: Controlled routes

The absence of radar is strongly felt. Authorities are frequently informed of violations

of their airspace by pilots who come across illegal traffic. They are also aware that

aircraft operators can operate with impunity in their sphere of sovereignty, without their

knowledge. This situation is mainly due to the large number of uncontrolled routes as

shown in table 3.7. Only 81.3 per cent of routes are controlled, and most of them by

conventional means of which limitations have been presented. It can be noted that all

the routes in the oceanic FIR are controlled. These routes are used by airlines flying

from South America to Europe.

In spite of the absence of radar, ASECNA’s air traffic services still provide the classic

elements of control, which is to prevent collision between aircraft in the air and on the

ground, and to speed up and regulate air traffic generally.

Aviation Weather

Table 3.6 reveals that MET equipments’ availability rate (92.8 %) is below international

standards. The performance of weather data collection systems are not better as shown

in the figure 3.19 which represents the system’s efficiency17 in June 2005. Only 68 per

cent of TAF messages were received, and the figures are event lower for METAR

messages, with 43 per cent success. Met stations’ efficiency varies from 77 per cent to

100 per cent. These bad performances have to be link to the poor quality of transmission

systems we presented earlier.

17 Number of messages received on-time divided by the number of messages due to be receive


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Figure 3.19: OPMET availability rate

0

50000

100000

150000

200000

250000

300000

350000

1

Metar required Metar received TAF required TAF received

Source: ASECNA, annual report, 2003

A large number of OPMET messages are received more than 15 minutes after their

transmission. This impacts pilots and controllers’ ability to quickly react in case of

severe weather conditions.

More than 40 per cent of weather irregularities are related to low visibility. Another 40

per cent are due to storms, and the others are windshears, strong winds, and rains. Pilots

are often confronted to these conditions following inaccurate forecasts. Very often they

have to engage deviation manoeuvres. Go-Around, Release, Landing delayed, half turn.

These are extra fuel consuming operations for airlines.


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3.14 Conclusion

The aim of this chapter was to analyse the performance of ASECNA’s air navigation

system, and to highlight its shortcomings. Air navigation characteristics are as follows:

1. Traffic and complexity are increasing, though they remain at low levels when

compared to Europe or North America.

2. The airspace is strongly fragmented at a continental level, though there is relatively

low fragmentation within ASECNA’s own airspace. There is little harmonisation

and more cooperation is required with neighbouring providers to improve cost

effectiveness and deliver a seamless airspace to users.

3. Capacity is not a priority as traffic density and controllers’ productivity remain low

despite projected traffic growth

4. Delays are not the result of air traffic services

5. Safety is the critical issue of concern in ASECNA, as the region, though recent

figures show improvements. The number of safety events remains very high

relatively to the level of traffic. Conventional systems used are often outdated and

unreliable as they do not achieve international standards. It is also shown that

ASECNA is characterised by wide inhospitable areas that render the access to

equipments and their maintenance very difficult.

6. There is not a proper safety management system, and data are not systematically

collected and thoroughly analysed. Safety data are not made available to the public.

7. The use of conventional navigation aids generates flight inefficiency, and is costly

to users. But it would be unachievable to reduce inefficiencies to zero. Performance

targets need to be set, but there is a trade-off to be done with other performance

areas, such as safety.

8. ASECNA’s airspace is used by airlines from around the world. 80 per cent of

ASECNA’s revenues come from foreign or international airlines. This means the

agency must adapt its service, and responds to their needs.

9. ASECNA is relatively cost effective when compared to Europe and the USA. But

there are rooms for improvement as the cost staff costs are very high.

10. ASECNA is a solvent organisation. Its operating ratios and its borrowing power are

good.

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Chapter 4: CNS/ATM Systems and Concepts

The aim of this chapter is to present the main CNS/ATM systems and concepts, and to

determine suitable solutions for ASECNA, based on experimental performances and

local characteristics.

4.1 Introduction

The process of getting an aircraft safely and efficiently from its origin to its destination

requires effective Air Traffic Management systems supported by three key functions:

Communications, Navigation and Surveillance (CNS). The concept is based primarily

on the following technologies: data link communications, digital aeronautical

information services (AIS), the Global Navigation Satellite System (GNSS) and

Automatic Dependent Surveillance (ADS).

CNS systems are a set of technologies employing digital techniques, including satellite

navigation systems, together with various levels of automation. These are applied to

support a global Air Traffic Management system. The strategic vision is to foster a

global ATM system that enableS airspace users (Aircraft operators), to better meet their

schedules, and to adhere to their preferred flight profiles with fewer constraints. Of

course, this has to be done without lowering the safety levels. These technologies will

enable the transformation of air traffic management to provide for collaborative

decision-making (CDM)1, dynamic airspace management, strategic conflict

management, flexible use of airspace and all weather operations.

The airline industry is looking for ways to improve its bottom-line profitability as

shown in chapter 2. It is focusing its efforts on the need for change. One Sky, global

ATM is the industry's vision of a global air navigation system that improves Safety and

Efficiency whilst accommodating worldwide air traffic growth in an airspace that is

1CDM brings together airlines, civil aviation authorities and airports in an effort to improve air traffic

management through information exchange, data sharing and improved automated decision support tools. This philosophy of collaboration promises to become the standard in aviation. CDM enables information sharing and facilitates decision making processes by ensuring that stakeholders are provided with timely and accurate information, essential for the planning of their operations (IATA)

Chapter 4 CNS/ATM systems and concepts

71

seamless and devoid of national borders. According to IATA, achieving this vision will

result in a wide range of benefits such as, environmental benefits (Reduced emissions),

and lower overall costs for the airlines through operational improvements, efficiency,

avionics equipage and equitable user charges.

Therefore, CNS/ATM systems are crucial to the industry, in their attempt to simplify

the business, and to gain more freedom in the way they operate.

ANSPs expect that better communications, navigation and surveillance systems will

undoubtedly increase the level of safety. With the use of voice and data

communications, satellite and precision navigation, SSR Mode S and ADS surveillance,

and all the other new concepts, ANSPs will significantly reduce the hazards due to the

use of conventional systems.

A common digital aeronautical information exchange model is the industry’s objective.

The new systems make possible the sending of right information to the right user at the

right time. Particularly, satellite technology and data link provide, where it is used for

aviation weather purposes, a highly reliable, fast and efficient method of

communication. Faster and more-efficient transmission methods ensure that much more

information can be made available. Suppliers of meteorological aviation data can

therefore provide a more comprehensive service to airline operators.

Capacity will be increased thanks to the implementation of new ATM practises and

concepts. RVSM (reduction of vertical separation limits) has already brought

consequent capacity gains where it is been applied (In Europe and Northern America

for instance). More capacity also means increased safety margins in non-congested

airspaces.

States consider Air transport industry as a critical component, and a development tool

for their economies as explained in chapter 2. A performing and safe air navigation

system that can absorb air traffic growth and guarantee safety must be considered as a

matter of strategic importance. Developing states like those in ASECNA are provided

with a timely opportunity to enhance their air navigation infrastructures. Countries in

ASECNA, as many developping nations continue to have large parts of their airspace

available but unsusable because they are unsafe as shown in chapetr 3. This is due to the

cost of maintaining the necessary ground infrastructure. According to ICAO,


72

CNS/ATM systems offer them opportunities to modernize at a low cost, their air

navigation system. Moreover, the impact of air transport on environment increases with

the industry’s growth. States are committed to reducing aviation emissions. By allowing

efficient aircraft operations and fuel consumption reduction, CNS/ATM systems appear

to be a part of solution to achieve that goal. That’s why states have to assist the industry

in that modernasation process, by facilitating financing and cooperation.

4.2 Suitable CNS/ATM systems for ASECNA

The following tables summarize ASECNA’s characteristics and indicate the

corresponding current solutions used, and CNS/ATM alternatives, that are supposed to

bring significant improvements.

4.2.1 Geographic characteristics

Characteristics Current systems CNS/ATMInhospitable areas

Deserts HF , Deported VHF CPDLC, ADS-B, ADS-COceans HF ADS-B, VDL, HF data linkForests HF, Deported VHF ADS-B, VDL, HF data link

4.2.2 Efficiency

Characteristics Current systems CNS/ATMFixed routes VOR, DME, NDB GNSS, RNAV, RVSM,

RNPFuel Inefficiency VOR, DME, NDB CPDLC, RNAV, RVSMLow airport accessibility ILS, DME GNSS

FragmentationDuplication of Equipments, Separated Civil aviation authorities

Regional Harmonisation

MET data accuracy Low Speed Transmission, AFTN

Digital Transmission, ATN

Controllers’ Productivity ATC ATM, CPDLC, ADS-B


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4.2.3 Capacity for Safety

Characteristics Current systems CNS/ATM

Poor safety records

Voice Communication, Ground based separation assurance, strips, primary

radars

Data Link, CPDLC, Radars mode S

4.2.4 Surveillance

Characteristics Current systems CNS/ATMPoor surveillance Primary radars, Voice

reportingADS-B, HF data link, radars mode S

Runway incursions Visual surveillance Multilateration

Range limitation Satellite based VHF, HF AMSS

4.3 Study of selected systems

4.3.1 Communication systems

The communication requirements for each phase of flight depend on the controller-pilot

communication needs. These requirements vary with the traffic complexity and density,

the weather conditions, the controller’s needs to issue clearances and vector2 the

airplane or to establish contact with the aircraft crew. Enhanced communication

performance is provided through air-ground data link communications integrated into

the Aeronautical Telecommunication Network (ATN) to complement the current voice

communications means (see ATN page 83). Voice communication will be used for

critical messages, such as vectoring to avoid traffic and landing clearance at airports

with heavy traffic. It will also serve as back up.

2 Headings by the ATC to an aircraft, for the purpose of providing navigational guidance


74

Figure 4.1 : Aeronautical communication links

Data Link

A key feature of communication is the use of digital Data Link as a primary means for

exchanging aeronautical information and delivering ATC services: pre-departure

clearance (PDC), digital Automatic Terminal Information Service (ATIS), selected

Flight Information Services (FIS) and oceanic ATC services for instance. Today’s most

prominent Data Link advanced features are CPDLC and VDL, Mode S Data Link.

CPDLC (Controller Pilot Data Link Communication)

CPDLC is an important tool that addresses the problems generated by the growth in

aviation communications and the accompanying needs for effective communications,

and acceptable safety levels (Hancock, 2005). CPDLC resolves a number of drawbacks.

For instance, it provides automatic data entry capabilities. This permits ground systems

and airborne flight management computers to enter critical information, such as flight

routes… etc. It cuts down on errors resulting from manual data entry. It also permits a

significant reduction in transmission time, thus reducing the congestions. It eliminates

misunderstanding due to a deficient quality of the voice received, propagation problems,

dialects and the possibility of having instant access to previous voice transmission

recording. The following figure represents a screen shot of a CPDLC message between

CCoommmmuunniiccaattiioonnss

Ground: ATC, ANSPs, AOC

Aircraft 1

Satellite

Aircraft i

Ground: ATC, ANSPs, AOC


75

a controller and a Pilot. The ATC ask the pilot to climb at a certain altitude, and the

pilot replies that the aircraft performance could not tolerate this manoeuvre.

Figure 4.2 CPDLC test message on SAS3 B737-600 LN-RRZ MCDU

Source: SAS, 2005

CPDLC Trials

As explained, CPDLC supplements the essential communications bridge between

controllers and pilots. It helps to reduce routine workload, non-time critical exchanges

from the voice channel to a data channel, freeing the voice channel for time critical

communications such as vectors around weather or traffic.

Voice channel occupancy: In high fidelity simulations conducted at the Federal

Aviation Administration's (FAA) Technical Centre, the voice channel occupancy

decreased by 75 percent during realistic operations in busy en route airspace. The net

result of the decrease of voice channel occupancy is increased flight safety and

efficiency through more effective communications between controllers and pilots, with

fewer missed, repeated, and misunderstood communications.

Capacity Gains and Workload reduction: A real-time simulation performed at

Eurocontrol’s experimental centre during the year 2000 investigated the use of voice

radio frequency at three levels of traffic volume: baseline study day traffic, and 150%

3 Scandinavian Airways


76

and 200% of the baseline volume, and at four levels of Data Link aircraft equipage: 0%,

50%, 75% and 100%. A clear positive correlation was obtained between aircraft

equipage level and reduction in voice frequency usage. The following figure presents

the results (Boeing, 2000).

Figure 4.3: Estimated Capacity gained as a function of percentage of CPDLC

equipage

Source: Mitre Corporation, 2005

Working with these data, Eurocontrol used findings from previous non-data link studies

conducted by National Air Traffic Services (NATS), in the United Kingdom and the

Centre d'Études de la Navigation Aérienne (CENA) in France to estimate reductions in

total sector workload associated with communication under current voice-only

conditions (table 4.1). These earlier results indicated that communications normally

constitute 35% to 50% of total sector workload. Based on the reductions in frequency

usage previously identified in the real-time simulation, Eurocontrol calculated total

sector workload reduction due to CPDLC for each level of data link equipage using the

conservative estimate of communications workload (35%). The link between sector

workload and airspace capacity was estimated using prior results obtained with an ATC

Capacity Analyser tool.


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Table 4.1 Workload reduction as a function of aircraft equipage(Boeing, 2000)

The results suggested that proportional sector capacity increases are approximately

one-half of the amount of workload reduction achieved in a sector. The results of the

workload reduction calculations performed by Eurocontrol in 1999 are presented in

table 4.1 above.

Delays reduction: Eurocontrol investigated the impact of traffic and capacity variations

on Air Traffic Flow Management (ATFM) delays in the European airspace. The traffic

sample and the airspace used for the delay calculations were identical to those used in

the real-time simulation baseline described previously. The results are shown in table

4.2 below.

Table 4.2: Delays Reduction as a Function of aircraft Equipage

(Boeing, 2000)

As suggested earlier, future efforts should allow to identify and to quantify benefits that

will be gained not only by airspace users, but also by ANSPs. For the later, benefits

flow directly from the increase in productivity (controllers’ workload, capacity)

associated with the use of CPDLC. However, they are realized as an alternative means

to increase airspace capacity without increasing the number of en-route control centres.

The keys to assessing the benefits of CPDLC lie in an understanding of how CPDLC

facilitates the job of air traffic controllers, and how these changes affect the effective

capacity of airspace and the associated costs of maintaining a safe and efficient air

traffic system and the cost of using it.

Percentage Aircraft Equipage Workload Reduction0% 0%

50% 16%75% 22%

100% 29%

Percentage Aircraft Equipage

ATFM Delay reduction Overall Delay reduction

0% 0% 0%25% 10% 2.5%50% 31% 8%75% 44% 11%100% 53% 13%


78

The physical infrastructure that supports the CPDLC is the VHF Data Link (VDL)

presented below.

VHF Data Link (VDL)

VHF analog communication means available today are not compatible with CNS/ATM

technologies. VHF Data Link operations require a VHF digital radio. VDL is essential

for Data Link; VDL formats specify a protocol for delivering data packets between

airborne equipments and ground systems similar to that used in Aircraft

Communication Addressing and Reporting SystemS (ACARS). The difference is that

VDL provides a capacity 10 times greater than the equivalent of 25 KHz VHF channel.

VDL Mode 1: VDL mode-1 is a low speed bit oriented data transfer system. It uses

carrier sense multiple access (CSMA4) protocol. The new development has overtaken

VDL mode-1, which is no longer in use.

VDL Mode 2: It is an improved version of VDL Mode 1 and it uses the same

technology and Differential 8 Phase Shift Keying (D8PSK) modulation. It is supported

by VHF and HF capabilities. Its average data transmission is 31.5 kbps5. This is over 13

times the VHF ACARS 2.4 kbps rate using Double Sideband Amplitude Modulation

(DSB-AM). It employs a globally dedicated common signalling channel6 (CCS) of

136.975 MHz.

VDL Mode 3: it is an integrated digital data and communication system allows to use

up to four voice and/or radio channels on a single carrier with 25 KHz spacing. The data

link technology used is called TDMA7. The data capability provides a mobile sub

network that is compliant to the Aeronautical Telecommunication Network.

4 Carrier sense means that every device on the network listens to the channel before it attempts to transmit the information. Multiple access means that more than one network devise can be listening at the same time, waiting to transmit the data. 5 Kilo Byte per second

6 Signalling is the use of signals for controlling communications. CCS means that a data channel in combination with its associated signalling terminal equipments. It only requires one signalling channel for up to 1000 data communication channels and is able to do this by only signalling when required.

7 TDMA is a technology for delivering digital wireless service using time-division multiplexing (TDM). TDMA works by dividing a radio frequency into time slots and then allocating slots to multiple calls.


79

VDL Mode 4: It uses a data link technology called self-organizing time division

multiple access (STDMA). In this mode, stations transmit their geographical position

together with data message in time slots that are dynamically modified at frequent

intervals.

Before starting a transmission using the STDMA technique, the aircraft keeps listening

on the frequency to be used and establishes a track and a table of time slots for all other

aircraft. An algorithm in the aircraft transceiver selects a free slot or takes the slot of the

most distant aircraft. This modulation system allows distant stations to transmit in the

same slot with little interferences. The aircraft is not involved in any manual frequency

tuning for any station change. Reception of the geographic position gives a surveillance

capability. VDL mode 4 is a candidate technology for ADS-B operations.

Airlines prefer VDL Mode 2. The technology is perceived as the only logical choice

because it is a globally accepted standard supported by the communication service

providers such as SITA8 and ARINC9. VDL Mode 2 has been standardized as a digital

data link to be shared by Air Traffic Services (ATS) and Aeronautical Operational

Control Centres (AOC). This is done within the framework of ICAO’s standardized

Aeronautical Telecommunications Network (ATN).

Mode S Data Link (Mode Select)

Mode S is use for surveillance as it’s will be explained later in page 96. Nevertheless, it

also makes available an air-ground data link, which can be used by ATS in high-density

airspace.

Mode S Transponders send and receive data link messages via Mode S message

formats. During normal operation, ATC ground stations and other aircraft automatically

receive altitude, discrete address, and transponder code via interrogate and reply

formats.

8 Societe International des Telecommunications Aeronautiques

9 Aeronautical Radio Inc


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The Mode S ground interrogator transmits a sequence of pulses. The timing, the level

and the sequence of the pulses determine the interrogation mode. The ground

interrogator can distinguish between the surveillance function and the data link function

due to the availability of different pulses, pulse amplitudes and pulse times. Mode S

data link function uses four distinct pulses.

Aeronautical Mobile satellite System (AMSS)

AMSS are geostationary communications satellites, designed especially for mobile

communications, which offer wide/near global coverage and voice and data

communications. The digital voice component of AMSS is designed to interface with

terrestrial public switched telephone network (PSTN) and to provide high quality

telephone service both for aeronautical passenger communications (APC), ATS &

Aeronautical operational control (AOC). The use of AMSS is particularly suitable for

cross-oceanic flights.

High frequency Data Link (HFDL)

The HF data link provides an air-to ground data link that is ATN-compatible. Its

development within lCAO has progressed rapidly and appears to provide an alternative

and possibly cheaper communication medium than SATCOM for data. HF data link is

also an excellent standby system for the AMSS presented above, in oceanic and remote

areas. Aiircraft can contact three or more HFDL ground stations constantly and its hub

can become ATN routers. The dependence on HF voice continues to remain the

backbone for ANSPs communication systems in oceanic and remote regions.

AMSS, VDL, Mode S and HF data link use different data transmission techniques.

Individually, they all use the same network access protocol in accordance with

International Standardization Organisation (ISO). This allows the interconnection

between these technologies and other ground-based networks. The communication

service that allows ground, air-ground and avionics data network to interoperate is the

Aeronautical telecommunication Network presented in figure 4.4.


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Aeronautical Telecommunication Network (ATN)

“Without ATN, there is no CNS/ATM”. (Dr Hilaire Tchicaya, Head of Aeronautical

Telecommunications, ASECNA). In fact, ATN is the inter-networking infrastructure for

the technologies presented above and others. ATN will link the various air-ground data

systems together.

A variety of ground networks, implemented by states, a group of states or commercial

networks that use packet switching techniques and are compatible with ISO’s OSI

reference model will be able to use ATN’s internetworking services. With the gradual

implementation of ATN, the use of the current Aeronautical Fixed telecommunication

network that serves to transmit messages between ANSPs, and between ANSPs and

users. AFTN will diminish. However, during the transition period, interconnection of

AFTN terminals to the ATN will be possible via special gateways.


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Figure 4.4 Aeronautical Telecommunication Network concept

Source: ICAO, 2002, p.69

ATN allows communication between all the stakeholders. The design provides for

incorporation of different air-ground sub networks and different ground-ground sub

networks, resulting in a common data transfer service. The two aspects are the basis for

interoperability that will provide a reliable data transfer service for all users.

Furthermore, the design is such that user communication service can be introduced in an

evolutionary manner.

As shown in Figure 4.4 above, the routing of messages over ATN are controlled by

routers. The routers direct data messages to their destinations. ATN aims at operating

globally, encompassing all aeronautical data communication services.

FMS

ATSAirline Operation Control

Airline Admin Service

AirlineData Base

Cabin Crew Interface

PAX Interface

Flight crew Interface

Airborne Network

VHF Link

Satellite Link

Mode S Link

Router

ATFM

Router

Private Ground Network

ATS ground

NetworkGateway to PDN

Gate Link

HF Link


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4.3.2 Navigation systems

CNS/ATM navigation technology improves the accuracy of the position and provides

better predictions of future positions to enable aircraft to fly more accurately..

Improvements in navigation include the progressive introduction of area navigation

(RNAV) and required navigation performance (RNP) capabilities along with the global

navigation satellite system (GNSS). These systems provide for worldwide navigational

coverage and are being used for en-route navigation and for non-precision approach.

With appropriate augmentation systems and related procedures, it is expected that these

systems will also support precision approaches even under bad visibility conditions.

Global navigation satellite System (GNSS)

GNSS is a satellite system that is used to pinpoint the geographic location of a user's

receiver anywhere in the world. Two GNSS systems are currently in operation: the

American system: Global Positioning System (GPS), and the Russian's Global Orbiting

Navigation Satellite System (GLONASS). A third one, Europe's Galileo, is slated to

reach full operational capacity in 2008. Each system employs a constellation of orbiting

satellites working in conjunction with a network of ground stations.

Satellite-based navigation systems use a version of triangulation10 to locate the user,

through calculations involving information from a number of satellites. Each satellite

transmits coded signals at precise intervals. The receiver converts signal information

into position, velocity, and time estimates. Using this information, any receiver on or

near the earth's surface can calculate the exact position of the transmitting satellite and

the distance (from the transmission time delay) between it and the receiver.

Coordinating current signal data from four or more satellites enables the receiver to

determine its position. There are nearly 30 satellites giving an accurate positioning and

timing information worldwide. They can be used to give positioning accuracies of better

than 10 metres and timing accuracies of better than 30 nanoseconds.

World Geodetic System coordinates (WGS-84): An important tool in implementing

these navigation principles are the World Geodetic System coordinates (WGS-84).

10 Triangulation is a process by which the location of a radio transmitter can be determined by measuring either the radial distance, or the direction, of the received signal from two or three different points. Triangulation is used in aviation to pinpoint the exact geographic position of an aircraft for instance.


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WGS-84 coordinates system is a conventional earth model, established in 1984 from

assembled geometric and gravitational data. This model portrays the earth as being

ellipsoidal, contradicting former beliefs that the earth was spherical (ASECNA, 1996).

The origin of this system is the earth's Centre of mass (assuming for simplicity that the

earth rotates at a constant speed around a fixed meridian pole).

The WGS-84 system responds to the present navigational needs: RNAV, RNP, ATS

routes and satellite navigation. In 1989, ICAO adopted WGS-84 as the standard

geodetic reference system for future navigation (For further information, refer to

Appendix 3).

Satellite Based augmentation Systems (SBAS): There are four Satellite Based

Augmentation Systems being developed: EGNOS in Europe, GAGAN in India, MSAS

in Japan and WAAS in the USA. These are all civil-controlled regional systems and

there is a form of coordination to ensure that they are interoperable to provide a

seamless worldwide navigation system so that one SBAS/GPS receiver can be used all

of them. Each SBAS provides GPS corrections to improve positioning accuracy to

around 1 metre horizontally and 3 metres vertically. Timing accuracy is enhanced to

better than 10 nanosecondes.

ASECNA has chosen the European Augmentation Systems EGNOS as part of his

satellite navigation strategy.

European Geostationary Navigation Overlay Service (EGNOS): EGNOS, the

European Geostationary Navigation Overlay Service, is a SBAS that is being deployed

to provide regional satellite-based augmentation services aviation, maritime and land-

based users in Europe. EGNOS is the first step in the European Satellite Navigation

strategy that leads to Galileo. Availability is improved by broadcasting GPS look-alike

signals from up to three geostationary satellites; accuracy is improved to between 1 and

2 metres horizontally and between 2 and 4 metres vertically; Integrity and Safety are

improved by alerting users within 6 seconds if a malfunction occurs in EGNOS or GPS.

The following are the benefits that are derived from EGNOS.


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Figure 4.5: Comparison between EGNOS and GPS

Source: ESA, 2004

EGNOS enables Precision Approach Operations (APV 2 and APV 1)11. They are

achievable on every runway. The Integrity of EGNOS vertical guidance protects aircraft

against CFIT12 accidents. Thanks to SBAS APV1, all non-precision approach (NPA)

procedures are suppressed. New SBAS APV1 services open the door to new feeder

routes between secondary and inter national airports. New APV1 procedures suppresse

the need of CAT-1 service for many runways

A major advantage of this system is that it requires less costly ground installations than

is required by present conventional systems. It allows the full coverage of navigational

services over sparsely populated, desert and forest areas. It must be highlighted that

there is no technical requirement for the implementation of EGNOS ground stations in

each African country. In other words, this means that EGNOS service provision scale is

at regional (i.e. sub-continental) supra-national level.

11 Approach Procedure with Vertical guidance12 Controlled Flight Into Terrain


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EGNOS Trials

The aim of the flight trial was to assess EGNOS’ capability to provide aircraft guidance

during two different approach types:

1) Straight-in ILS look-alike approaches: Guidance was provided by the

flight director and autopilot of the aircraft’s Flight Management System.

2) Curved approaches: Guidance was provided by the flight director of the

Research

The following parameters among others that are not reported here have been

investigated:

Accuracy: The navigation system error (NSE13), the total system error (TSE14),

Integrity, and Noise Contour.

13

The navigation system error (NSE) is defined as the difference between the actual flight path (i.e. Trimble reference position) and the flight path indicated by the navigation system in the lateral and vertical plane.

14The Total System Error (TSE) is defined (See figures above) as the difference between the desired

flight path and the actual flight path (i.e. Trimble reference position).


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The Results

The Total System Error (TSE)

Figure 4.6: Lateral and Vertical TSE for three approaches. (Red=1st approach, Green = 2nd, Blue = 3rd approach. A minus sign means Left/Below

desired position; a plus sign means right/Above desired position).

The performance in terms of the Horizontal NSE and the Vertical NSE were found to be

in the order of 1-4 m (95%) in the lateral and vertical plane and can be rated as very

good according to Eurocontrol. The lateral APV-II and CAT I requirements as specified

in ICAO SARPs were easily met (tables 4.3, 4.4 and 4.5 below). The vertical APV-II

criteria specified in the SARPs were met during all curved approaches.

95% AccuracyProcedure Lateral (m) Vertical (m)

Nice results 3.9 4.9

95% AccuracyICAO SARPS APV I APV II CAT I

Lateral (m) 220 16 16Vertical (m) 20 8 4-6

AvailabilityAPV I APV II CAT I

Nice 100% (100-99,92) % 100%ICAO 0.9999 0.9999 0.9999

Distance to the runway Distance to the runway

Table 4.3

Results for lateral vertical accuracy

Table 4.5: ICAO’s SARPs for lateral and

vertical accuracy

Table 4.4

Results for Availability Vs ICAO’s SARPs


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In general, the aircraft arrived at the runway threshold slightly right of centreline during

the curved approaches. The navigation system error was relatively small.

Noise Contour: This noise impact study confirmed that the Riviera approach reduces

annoyance for the local area, especially at the located right below the ILS eastward

approach trajectory. The study also revealed that the use of a SBAS navigation system

might bring further improvements around the southeast local area by considerably

reducing the dispersion of aircraft trajectories. However, for the SBAS scenario all

aircraft were assumed to have the same 3D trajectory, which is a strong assumption.

The benefits of SBAS guidance in terms of noise will strongly depend on the way it is

implemented and how pilots and controllers respect procedures.

GNSS and improvements in avionics allow better navigation and approach manoeuvres.

Area Navigation and Required navigation performance are two of the main concepts

made possible by these CNS/ATM tools.

RNAV (Area Navigation)

Area Navigation is a method of navigation that enables an aircraft to fly in any desired

path within the coverage of referenced air navigation aids, or within the capacity of self

contained systems or a combination of both. The use of routes and procedures based on

RNAV, improves access and flexibility, through point-to-point navigation. These routes

are not restricted to the location of ground based NAVAIDs. Safety of such operations

is achieved thanks to a combined use of navigation accuracy, ATC monitoring,

communication, multilateration15, or increased separation.

RNAV was developed to provide more lateral freedom and a better use of available

airspace. This method of navigation does not require a track directly to or from any

specific radio navigation aid as explained above, and has three principal applications:

1) A route structure can be organized between any given departure and arrival

point to reduce flight distance and traffic separation.

15 Multilateration is today’s version of triangulation (use of three satellites to locate an object), where the location of an object is determined by taking its bearing from several different places.(Refer to appendix 2 for more details)


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2) Aircraft can be flown into terminal areas on varied pre-programmed arrival

and departure paths to expedite traffic flow.

3) Instrument approaches can be developed and certified at certain airports,

without local instrument landing aids at that airport.

The following figures represent the navigation performance when using RNAV or RNP.

They clearly show the advantages of new systems in term of efficiency.

Figure 4.7: Comparison between RNAV, RNP and Conventional navigation

Source: Federal Aviation Administration, 2006

Trials have been conducted and RNAV is already implemented in many parts of the

world since the year 2000. The following are the results from trials in Atlanta (USA).

RNAV Trials

As the next figure depicts it, Non RNAV flights are characterised as follows:

1) Departures are vectored

2) Headings, altitudes and speeds issued by controllers

3) Large number of voice transmissions required

4) Significant dispersion

5) Tracks are inconsistent and inefficient and there are limited exit points

Optimised Efficiency with

RNP

Improved Efficiency with

RNAV

Inefficiency with Conventional

systems


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Results

Figure 4.8: Atlanta SID trials: Non RNAV tracks

Source : IATA, 2005

Flights with RNAV capabilities give the following results:

Figure 4.9: Atlanta SID, RNAV tracks

Source: IATA, 2005

The results are as follows:

Departures fly RNAV tracks are not vectored

Headings, altitudes and speeds are automated via avionics

Voice transmissions reduced by 30-50%

Reduced Track Dispersion

Tracks are more consistent and more efficient

Additional exit points available


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RNP (Required Navigation Performance)

RNP operations are RNAV operations that use on-board containment16 and

monitoring. The ability of the aircraft navigation systems to monitor its achieved

performances, and to indicate to the crew whether the operational requirement is being

met during an operation, is a critical component of RNP. Aircraft RNP capability is

important in determining the separation requirements to ensure that containment is met.

RNP approach is already being implemented in some American airports.

In the Caribbean and Latin America regions, introduction of RNAV is generating an

annual reduction of around 40,000 tonnes of CO2 emissions. In cross polar-routes,

satellite based navigation has enabled flights over previously untravelled territory using

Russian, Canadian and US airspace close to the North Pole. The first official polar route

flight between North America and Asia by a commercial airline was conducted in July

1998. Currently, more than 200 flights per month use near polar routes between Europe

and Asia and Asia and North America thereby benefiting airlines and passengers

through significant time and fuel savings and associated emissions reductions.

Figure 4.10: Projected RNP-RNAV capability, RNP capable aircraft:

Source: Eurocontrol, 2002

16 Onboard containment is onboard alerting and monitoring capability that reduces the reliance on Air Traffic Control intervention, via Radar or ADS, multilateration…


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American and European aviation regulators have recently approved the integrity of

navigation data provided by Boeing. It enabled carriers to use the information for

precision area navigation procedures: Carriers using the navigation data will be able to

implement new precision area navigation (P-RNAV) procedures. They require that

aircraft are able to maintain a track with lateral accuracy of 1nm (1.85km) for 95% of

the time (Kaminski-Morrow, August 2005)

As the figure 4.10 suggests, aircraft RNP and RNAV capability will be greater than 90

per cent by 2010. Which means no ANSP could ignore that, and therefore they need to

prepare themselves consequently to be able to offer that service to their users.

RVSM (Reduced Vertical Separation Minimum)

The goal of RVSM is to reduce the vertical separation above flight level (FL) 290 from

the current 2000-ft minimum to 1000-ft minimum. This will allow aircraft to safely fly

more optimum profiles, gain fuel savings and increase airspace capacity. The process of

safely changing this separation standard requires a study to assess the actual

performance of airspace users under the current separation (2000-ft) and potential

performance under the new standard (1000-ft).

RVSM was successfully implemented across 41 European and North African States in

January 2002. During the first summer of operations, ATM capacity in European

airspace was increased by approximately 15%.

4.3.3 Surveillance systems

Secondary Surveillance Radars are still being used, along with the gradual introduction

of Mode S presented below, in both terminal areas and high-density continental

airspace. The major innovations are the introduction of Automatic Dependent

Surveillance (ADS), Mode S surveillance and multilateration. The latter is not

presented here although it has great potential.

ADS systems allow the aircraft to calculate its position, its heading and other data such

as speed and useful information contained in the flight management system. The data


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are automatically transmitted to the air traffic control unit. ADS data are transmitted via

satellite or the communication means presented earlier (Data Link…). The position of

the aircraft is displayed on a screen like with a radar display. ADS is defined as the true

merging between Navigation and Communication technologies. Along with enhanced

ground systems’ automation, ADS helps to improve ATM, especially in oceanic

airspaces.

The need for new HF radios on Atlantic routes has been averted through the gradual

introduction, over the past few years, of ADS waypoints reporting, which allows better

flight plan conformance monitoring and a reduction in gross navigation errors.

There are presently three types of ADS: ADS-A, ADS-B and ADS-C. These are

presented below.

ADS-A (Addressable)

ADS-A enables appropriately equipped aircraft to send position information messages

at predetermined geographical locations or at specified time intervals. ADS-A can be

relayed via high frequency data link, satellite communication, and very high frequency.

Some pacific ATS providers already use Automatic Dependent Surveillance-

Addressable to apply 50 nm longitudinal separation between aircraft. ANSPs’ systems

in countries like New Zealand, Australia, Tahiti, and Fiji support the use of FANS 1/A

ADS-A operating systems in Pacific oceanic airspace (Cirillo, 2004).

ADS-B (ADS-Broadcast)

ADS-B involves broadcast of position information to multiple aircraft or multiple ATM

units. ADS-B-equipped aircraft or ground vehicle periodically broadcast their position

and other useful data derived from on-board equipments. This is called aircraft derived

data (ADD). The position is calculated through GPS and associated augmentation

systems. Any user, either airborne or ground-based, within range of this broadcast, can

process the information. It will remove the reliance on voice reports and is expected to

add significant en-route safety. The technology is also envisaged to be applied for

surface movements, thus being an alternative to surface radars such as airport surface

detection equipment.


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Figure 4 .11: ADS-B operational capabilities.

Source: RockwellCollins.com

The figure above (figure 4.11) illustrates the operational capabilities of the technology.

It will bring significant operational enhancement in airport surface management, air-to

air and air-to-ground communications, and in surveillance operations. On airports’

surface, it will enhance pilots’ situation awareness, and above all, it will reduce

runway. In-flight, ADS will improve separation standards.

ADS-B Operational trials (Bundaberg, Australia)

In recent years, Australia has been active in the field of automatic dependent

surveillance-broadcast because the technology offers the possibility of continent-wide

coverage.

In 2002, Air Services Australia installed a single ADS-B ground station at Bundaberg

and equipped a number of aircraft with ADS-B avionics. They modified Australian

ATM system to process and display ADS-B tracks. The data link technology used was


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Mode S extended squitter17. The focus of Bundaberg’s trials was to improve lower level

surveillance coverage to allow early insurance of clearances as aircraft climbed into

controlled airspace. 28 ADS-B ground stations are planned nationwide. Some will

replace 11 secondary surveillance radars, saving a fortune in maintenance cost. Each

ADS-B station costs $1 million. It will replace a $US10 million worth radar that

costs $US1 million per year to maintain. The other ADS systems will provide

coverage in airspace that has never had radar.

Results

The systems performance exceeded expectations. Detection coverage, position

accuracy, velocity vector accuracy and update rate were found to be better the

conventional fast rotating monopulse secondary surveillance radar used (Dunstone,

2005).

Gotzenhein (Germany) Operational trials

This site was chosen because Frankfurt had been evaluated as the region with the

highest FRUIT density world-wide. The ADS-B antenna elements were positioned

either side of the airport radar tower for 360° coverage.

Results

Evaluated as a Terminal application (100 Nm) with a 4 second update rate,the

Probability of Detection (Pd) was greater than 99.8%.

Evaluated as an En-route application (150 Nm) with a 6-second update rate, the Pd was

above 99.6%.

As shown on the following figure (Figure 4.12), ADS-B is far better than Radar. While

radar data gated to 150 NM, ADS-B was only limited by terrain screening. The results

also showed a higher update rate, which allow a better accuracy (Wakefield, 2005).

17 Works on 1090 megahertz, and is recommended as initial worldwide interoperable ADS-B Link


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Figure 4.12: Comparison between ADS and Radar’s.

Source: Wakefield, 2005

ADS-C (ADS-Contract)

ADS-C is another ICAO standardised technique that allow aircraft to report data

items, including position, identity, intent, etc, to the ground over a point-to-point

data-link. It has been deployed mainly in oceanic areas and uses satellite

communications. However, it can also be used over any point-to-point data-link

(VHF, HF… etc). The technology is presently used only in areas of low traffic

density because of bandwidth limitations in point-to-point data-links.

Secondary Surveillance Radar Mode S (SSR-Mode Select)

Mode S radar is a relatively new type of secondary radar that is also based on the use of

a transponder on board the aircraft, responding to interrogations from the ground. The

radar thereby detects the aircraft with better link means, and above all retrieves

information that can help identify the aircraft at the same time.

Communication between conventional secondary radar and a conventional transponder

uses the modes A and C. When interrogated in mode A, the transponder replies by


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transmitting its code with the same name (allocated to the flight by air Traffic Control,

and entered by the pilot into the transponder via the interface). When interrogated in

mode C, the transponder replies by giving its altitude.

The radar mode S operates at the same frequencies (1030/1090 MHz). The Mode S

provides more accurate position information and minimizes interferences by discreet

interrogations of each aircraft. Its selectivity is based on precise identification of an

aircraft by its 24-bit address. That address can be considered as its communication

address and is linked to the aircraft, or at least to its transponder. But it does not replace

the Mode A code which is linked to a flight or a flight plan. There are also plans for

recovery of the A and C codes via Mode S.

4.3.4 Air Traffic Management

The future domestic ATM

Using satellite-based navigation and communication networking technologies presented

above, the future domestic and oceanic ATM systems will be seamless. They will

employ similar systems and procedures regardless of location. However, complete

transition to the new environment may not be completed in the near term. Therefore, the

near-term domestic CNS concept must maintain some reliance on current ground ATC

capabilities, albeit upgraded, particularly in terminal areas. Terminal air traffic

controllers will continue to separate and sequence aircraft. Pilot-controller connectivity

will include both voice and data. Radar will continue to provide some aircraft position

information but the introduction of Mode S secondary radars will facilitate the selective

interrogation of aircraft. In addition, ADS-B will be introduced in the en route structure

where aircraft broadcast position information derived from GPS and corrected by

augmentation systems to the ATM system. SBAS corrections will be transmitted from

ground earth stations through communications satellites. GPS and Augmentation

systems may also provide precision approach information in the future for aircraft,

eliminating the need for ILSs and precision approach radar (PAR). Data link

networks will route CNS data as presented earlier.


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The future oceanic ATM

In the near future, the greatest changes will occur in the oceanic environment. Here we

expect the full implementation of satellite-based CNS (ADS, Data-Link… Etc). Aircraft

will relay GPS/Augmentation-derived positions to ATM systems through satellites. The

same satellites will be used to relay aircrew requests and ATC instructions, many of

which will involve ATM to aircraft data links. The data link network will route CNS

information accordingly. In the oceanic environment, the first implementation of

aircrew-based separation is expected. Today, some airlines are already using a TCAS

“in-trail climb” procedure in which aircrews coordinate manoeuvres that allow aircraft

to pass one another.

4.4 Transition

The transition toward future systems needs to be accomplished gradually. A Cost

Benefit Analysis should precede each step. The FANS II committee developed the

transition’s guidelines (ICAO, 2002). These encourage that the states introduce some of

CNS components early enough in order to get rapid return on investments. The

conventional and the new system will have to co-exist during the transition period to

ensure people become familiar and confident with the new technology before

completely relinquishing existing technology. The two systems will have to inter-

operate (interoperability). But the guidelines aim at minimizing this period to the

extent practicable. But because of great difference in the level of ATM in various parts

of the world and other factors that have to be taken into account, a reliable time frame

can not be specified. Basing the transition to CNS/ATM systems on improvements in

ATM and structural and procedural changes is ideal. Airspace reorganisation is

required.

Commercial factors are also crucial and investments in satellite based systems by

ANSPs need to match that of domestic and international customers. Moreover, integrity

of the air navigation systems must be maintained throughout the transition phase. Any

removal of existing navigation aids has to be done after consultations with the users.

Planning and implementation of improved ATM systems should also include


99

consideration of training needs. The aviation community (Air operators, institutions and

service providers, manufacturers, states) have to cooperate to achieve these goals.

4.6 Affordability

With ICAO’s ATM Operational Concept and Global Air Navigation Plan, and IATA’s

ATM Implementation Roadmap, the airline industry has the potential to implement a

global airspace environment that will bring substantial operational and financial

benefits. However, implementing CNS/ATM systems will cost the industry money as

they will have to:

1) Upgrade aircraft avionics systems

2) Train the crews for the new systems and procedures

Progress towards the new systems have been slow. This lack of movement towards full

FANS implementation was not due to any particular technical problem, as the industry

effort had focused primarily on development of the technological case for CNS/ATM,

with many resulting competing technologies. The business case for CNS/ATM had

primarily been addressed at a cursory level, resulting in estimates of operational savings

without details on the benefit mechanisms. The ATM system must be considered as a

set of technologies; but it must also be considered as a business. The lack of

consideration of the economics of transition to the new operational concept has slowed

the pace of the implementation process (Allen et Al, 2005).

Airplane and ground system upgrades were slowed until they were confident that the

expenditures were justified. For an air carrier, a business case evaluation would include,

among other factors, assumptions about the impact on its costs of expected changes in

en-route charges and the impact on revenues of changes in air carrier fares and rates,

where these changes are associated with the implementation of CNS/ATM. These

impacts are in addition to the direct investment costs and operating cost savings

attributable to the new systems and identified in the cost/benefit analysis. The impact of

route charges will depend on the outcome of the policies and evaluations of the service

providers. Assumptions about fares and rates will reflect competitive pressures in air

travel and freight markets.


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Most of the basic practical guidance required relating to organizational options,

cost/benefit analysis, financial control, cost recovery and financing has been developed

following ICAO guidelines. The industry is confident that the new systems will bring

significant benefit to undertake such investments, and is participating to trials and

implementation programmes worldwide in collaboration with other industry’s

stakeholders (i.e. joint ASECNA and Air Afrique18 GNSS trials from 1994 to 2000).

For ASECNA, implementing new systems to improve the service will require

significant finance power. Between 2000 and 2010, installation and commissioning

amount to $US 276 million. This does not include interests on loans or depreciation. A

cost-benefit analysis for the 1995-2005 period shows investments of $US 235 million

including depreciation and interests. Expected incomes amount to $US 259 million,

essentially from air navigation charges. Airlines’ investments needs amount to $US 309

million. Expected comes amount to $US 341 million.

Big companies will be able to upgrade their fleet. But many small companies, which

own old fleet, will not be able to afford it. ASECNA will have to find adapted solutions

for them.

4.7 Conclusion

This chapter has allowed us to present the basic components of CNS/ATM systems.

How the proposed CNS/ATM technologies work, and how they actually deliver the

expected benefits to ASECNA has been studied. The study shows that the systems are

suitable to ASECNA as trials indicate that they could respond to its characteristics and

its problems. Satellite based navigation, data communication, and improved radar

surveillance, will render air traffic management much more efficient.

Future communication and satellite-based technologies will allow better exchanges

between pilots and controllers on both continental and oceanic airspaces. Trials

presented have shown that CPDLC, relying on high bit rates and more capacitive data

link techniques such as VDL, Mode S and satellite communication reduces

communication errors and reduce voice channels saturation and interferences. This

18 Before the airline’s bankruptcy


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means a safer communication environment. As controllers and pilots will loose less

time in unnecessary communications, this will have a positive effect on airspace

capacity, and increase safety margins. Moreover, controllers’ workload will

significantly been reduced, particularly in areas where traffic is relatively dense, which

will improve productivity and cost effectiveness in peak periods. In areas where traffic

is less dense, the new system will not have a significant impact, as controllers’

workload is already very low. At last, ATN will improve the quality, the speed and the

integrity of data transmission between users and service providers

Satellite navigation, in providing more navigation accuracy in conjunction with

augmentation systems, will allow aircraft to flight efficient trajectories and make a

better use of airspace with less dispersion, potentially avoiding diversion cost in bad

visibility conditions. Secondary airports will be accessed without the need of landing

aids. RNAV, RVSM, and RNP will increase route efficiency, safety, and capacity.

New surveillance technologies performance during trials (ADS, Radar Mode S) show

that aircraft detection and identification are improved in remote areas such as oceans or

deserts, and allow ANSPs to deliver a safer service at a significantly lower

acquisition and operating cost.

Big air operators are fitting their fleet with these capabilities. Small carriers will not

have the means to upgrade their old fleet. ASECNA has to adapt to each category’s

particular needs. At last, transition between the old and the new system requires

cooperation between the different stakeholders. To ensure a smooth shift in

technologies, interoperability between the systems is essential.

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Chapter 5: Analysis of ASECNA’s Modernisation Strategy

The aim of this chapter is to present and analyse ASECNA’s modernisation strategy, for each CNS/ATM component.

5.1 Description

5.1.1 Communications

ASECNA’s objective is the full deployment of an ATN environment with the

possibility to accommodate FANS1/A and the highest degree of functionality possible.

Fixed Network: ASECNA has embarked in the modernization of AFTN by high-speed

links and in the integration of its telecommunication systems. The Interconnection of

sub-regional communication networks and the setting up of an independent satellite

digital telecommunication network within its area, for AFTN and mobile

communications needs and for exchanges of meteorological data to assist ATM are

being implemented.

Data Communication: The use of secured and efficient protocols is expected to

increase end-to-end reliability of data transmission. A Flight data automation program is

engaged: The FIR Antananarivo already has FDPS, CPDLC and ADS-C capabilities.

Trials for similar systems and testing of a VDL sub-network and HFDL are being

conducted in Dakar.

VHF coverage: The VHF coverage programme is well advanced. Plans suggest that

almost all ASECNA’s routes will be covered and controlled by means of VHF radio,

except the Oceanic FIR. VHF has been deported to Agades, Zinder, Tessalit, GAO,

Dirkou (FIR

Niamey- Areas of Routing 3-4-9), Faya-Largeau (FIR N’Djamena AR-3) by means of

VSAT stations. Others are being implemented in Bir Moghrein, Nema, Taoudennit,

Tombouctou, Nouadhbou (FIR Dakar continental, AR 1-9), Moroni, Toamassima,

Tolangnaro (FIR Antananarivo,AR-10), Sao Tome and Principe, Bria, Makokou and

Pointe Noire (FIR Brazzaville, AR-4-5). A program to modernise VHF and HF


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equipments and installation of VSAT TS Direct speech facilities in other places are

also on the way.

5.1.2 Navigation

Successful flight trials in May 2005 from Dakar to Nairobi have been conducted, using

EGNOS. These followed other trials in West and Central Africa, conducted in February

2003 in Dakar, Senegal and in June 2003 at many airports of the States of Central

Africa (Nigeria, Cameroon, Gabon and Equatorial Guinea). GNSS approach

procedures are already available for all major airports in ASECNA.

As it is necessary to maintain adequate navigation service during the transition period,

ASECNA has launched a program to replace Navaids (VOR, ILS, and DME…) in

certain locations before the full implementation of GNSS. The use of satellite

technologies has allowed the Agency to implement 21 RNAV routes over its upper

airspace since 2004.

RVSM are already implemented in Antananarivo, Brazzaville, Dakar, N’djamena and

Niamey’s Flight Information Regions in accordance with ICAO regional agreements.

Since the beginning of 2006, operators wishing to penetrate this airspace received

RVSM aircraft airworthiness and operational approval from the appropriate state

authority.

5.1.3 Surveillance

Voice position reports remain the dominant procedure. However in high and medium

traffic density terminals and approach areas, SSR will be required while ADS will be

progressively introduced.

ADS/CPDLC

Antananarivo’s and N’djamena’s FIRs have already implemented ADS/CPDLC.

ASECNA was the first to develop ground equipments in the AFI region for the ADS. It

served to demonstrate the potential advantages of ADS displays in the AFI region.

These were the first ADS trials on the continental scale.


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As part of a surveillance exercise, ASECNA is currently carrying out ADS/CPDLC

trials in Dakar. Implementation plan (2001-2005) provides for the installation of ADS

systems in Dakar and in Sal Island (cap Verde) to monitor the oceanic FIRs. These

systems have screen displays capabilities in order to monitor the aircraft position at the

control centres. The display technologies used are:

1. FPDS (Flight Data Processing System)

FPDS contains Flight Plan Air Situation Display – FPASD – that deliver a graphic

representation of flights not fitted with FANS1/A equipments. The system is capable of

managing both paper and electronic strips.

2. ADS

Any aircraft fitted with ADS is able to automatically exchange data with the ATS

system. The aim is to simplify the coordination between traffic adjacent control centres.

3. CPDLC

The system will use CPDLC data exchanged between pilots and controllers to

automatically update corresponding flight plans.

Trials were still on-going in June 2005. But regulatory and normalisation requirements

slow the decision process.

Radar Mode S

It is planned to install 5 Monopulse SSR mode S radars with full ADS/CPDLC

capabilities in N’djamena, Dakar, Niamey, Brazzaville. Abidjan’s radar is already

operational. They should all be operational within 2 years (2007). Trials are being

conducted in N’djamena, Dakar and Brazzaville. The new system will be able to

manage at least 17 airspace sectors simultaneously, and will permanently be monitored

by 12 controllers, including optional positions, instead of 5 today. A total of 24 to 30

controllers, forming teams of 4 to 5 people, will be trained in that purpose. Other

surveillance projects include multilateration surveillance systems at Bir Moghreim,

Taoudenit, Tessalit, Agadez Bria, and Faya Largeau.


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5.1.4 On-board the aircraft

The aircraft of major international airlines linking Africa to Europe are already

equipped with built-in onboard CNS/ATM systems. Aircraft only flying national or sub-

regional routes are equipped with RNAV-1 systems and autopilot. A low-cost

CNS/ATM system composed of a VHF data link, an ADS mode and GNSS for

navigation is added to it. Communications and ADS surveillance benefit from VHF

cover and ATM automation on the ground. These aircraft are to be equipped with a C-

mode transponder for surveillance radar requirements in some terminal regions. The

design approach for the configuration of avionics is modular, to allow the evolution

from one ATM level to another.

5.1.5 Aviation weather

To better meet the airline demands, ASECNA is integrating the requirements expressed

via IATA into its equipment plans. Over the period 2000-2006, ASECNA has

strengthened the capacities of its meteorological centres by making the following major

investments:

1. Renovation and upgrading of systems (digital barometers, satellite imagery

receiving stations, etc.), meteorological information distribution and visualization

systems and forecasting systems (SADIS, RADAR, SYNERGIE, etc.);

2. Installation of the two-directional SADIS link in Dakar (Senegal) to serve as back-

up to the AFTN for OPMET data exchange;

These systems have not all been implemented yet, but the process is well advanced.

ASECNA is progressively migrating onto the Second Generation Weather Satellites

(MSG), with greater capacity of data processing (Flight planning dossiers, Turbulence,

Obstacle…etc) (Ndobian Kitagoto, Met Engineer, ASECNA).


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5.1.6 Air Traffic Management

ASECNA’s ATM Concept is primarily instituted between airports rather than gate-to-

gate1. Departure/arrival management will be implemented through SIDs and STARs and

not through fully integrated management like in ECAC for instance. The airspace will

offer some flexibility sizing capability, whereas ECAC will implement a dynamic

flight-to-flight adjustment. The agency has also planned to offer its users their preferred

routes within the filed flight plans, with some collaborative decision-making between

aircrew and controller using ADS/CPDLC, instead of free flight with autonomous

operations. Three dimensional RNAV based on GNSS and RNP has been preferred to

full autonomous aircraft with airborne conflict avoidance and separation assurance.

Under an agreement with the ATM systems manufacturer Thalès, EUROCAT2 air

traffic management system is being installed in Dakar (Senegal), Abidjan (Ivory Coast),

Brazzaville (Congo) and in Niamey (Niger). The EUROCAT advanced air traffic

management system provides safe and efficient operations in high density, complex

airspace. Its operational displays, radar networks and flight plan processing comply

fully with ICAO standards requirements. It integrates radar, ADS-C, CPDLC and ADS-

B surveillance facilities for the management of traffic over oceanic and large continental

areas. It will provide area and approach air traffic control. There will be a combined

total of 28 working positions across all four centres which will provide controllers with

advanced flight plan and radar processing, and the capability for several centres within a

FIR to use a common and centralised database for improved co-ordination between

centres and for sharing and handing over of flight information, search for and resolution

of conflicts, flexible and dynamic track processing and ATN interface and Flight data

link service, especially for aeronautical weather.

1 Gate to Gate operational concept is based on better collaboration between ATM actors and better planning to enhance the exchange of accurate and reliable data, resulting into increased capacity and safety (Hugo de Jong & Marc Soumirant, june,1st,2004).

2 The Eurocat air traffic management system is a highly integrated air traffic management system, currently used operationally in more than 100 flight information regions. To date, 130 EUROCAT air traffic management systems, in multiple configurations, have been purchased by more than 50 civil aviation authorities all over the world.


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Airspace rationalisation

Within the framework of airspace rationalisation and controls extension, ASECNA,

plans to create 2 sectors within the upper airspace (>FL 245) in the Dakar continental

FIR, and integrate the existing UTAs.

The long term objective of ASECNA is to reform ATM procedures by reducing the

number of number of UIRs (upper flight data regions) and the number of FIRs and

control centres, harmonizing TMA limits and integrating of sub-regional ATM systems.

RVSM

In order to increase its airspace capacity, ASECNA has implemented RVSM in parts of

its airspace. RSVM implementation3 in ASECNA’s area comes after what was done in

the Oceanic FIR, and in the EUR/SAM corridor.

5.1.7 Cooperation

Technical aspects

ASECNA is cooperating with its neighbours within the framework of ICAO’s

CNS/ATM regional planning. Technical cooperation includes telecommunications, and

some aspects of airspace rationalisation. Main cooperation activities are done with

ENNA (Etablissement National de la Navigation Aerienne, Algerian ANSP) and

SADC (South African Development Cooperation) led by ATNS.

In the light of the drawbacks in the interface and the experience acquired, ASECNA

and ENNA have established an efficient and viable co-operation framework that could

enable them to carry out their mission of ensuring the security and regularity of air

traffic more efficiently. A master plan establishing a framework of cooperation has been

established since 2000. The aim of the master plan for coordination and

harmonisation context, is to tackle the scope and diversity of the problems caused by

the extension of the FIR interface under ASECNA and ENNA management, the

shortcomings in terms of communications, the volume of air traffic today and the

3 Between FL 290 and Fl 410 included. RVSM will be implemented with the upper lateral limits of the following UIRs: Antananarivo, Brazzaville, Dakar continental, Dakar Oceanic, N’djamena, Niamey, and SAL oceanic.


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envisioned growth, the application of the new ICAO civil aviation navigation system.

Ultimate goals are better coordination and harmonisation aiming at: harmonising

working procedures and methods; creating air routes; harmonising their means of co-

ordination; joint use of technical equipment; co-ordinating development activities and

exchanging information, particularly, with regard to CNS/ATM systems and the

exchange of personnel.

Considered as the appropriate framework for promoting the security and regularity of

air traffic, this plan which conforms to the ICAO recommendations will make it

possible to homogenise the levels of performance of the two systems.

Cooperation with SADC is well advanced. The interconnection of the SADC and

ASECNA VSAT networks allows Johannesburg to communicate with Congo

Brazzaville and Madagascar (Antananarivo) through the AFISNET4 network whilst

Antananarivo communicates with Beira (Mozambique) and Dar es Salaam (Tanzania)

through the SADC network. In ensuring a balanced solution, ATNS installed a SADC

terminal in Antananarivo and ASECNA installed the AFISNET terminal in

Johannesburg. The agency has migrated on Intelsat 10.02 with Nigeria, Ghana, and

other neighbouring Airspaces. It’s waiting for the others (CAFSAT, SADC) to join

them on the same satellite transponder.

Cooperation with Nigeria is very limited as this country has just started to build a

viable air navigation system. Nigerian Airspace Management agency (NAMA) was

created in 2000 following the Kenya Airways Airbus crash off the coast of Cote

d’Ivoire, killing 69 Nigerians on board, after it could not land in Lagos due to poor

visibility and the unavailability of instruments landing systems. The Agency has since

launched an ambitious modernisation programme and is cooperating with ASECNA

4 In view of the difficulty of developing a network on a landline infrastructure, the AFISNET West Africa sub-network is the first slice of this AFISNET aeronautical network developed by ASECNA. It is based on the installation of Earth stations sited directly on the major operating sites (airports, VHF remote antenna). The Earth stations of Bangui, Brazzaville, Douala, Libreville, and N'djamena have been in service since April 1995. The Dakar and Abidjan Earth stations have been in service since 1996. ASECNA operates and maintains the oldest and largest international satellite network dedicated to the needs of air navigation. The AFISNET network is composed of about fifty Earth stations, grouped into two sub-networks:


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which calibrates its Navaids equipments. Nevertheless, Nigerian airspace is developed

to meet domestic requirements.

Like in ASECNA, EUROCAT systems have already been planned elsewhere across

Africa including Nigeria, Sudan, Algeria, Egypt, South Africa and Mauritius. By

implementing similar systems each ANSP can benefit from a greater regional

interoperability and enhances the continent’s air safety. As ASECNA is the most

advanced form of air navigation integration, it’s calling for the others to adopt its

model, in order to deliver a seamless airspace.

The concept of “single African sky”

ASECNA and ATNS (South Africa Service Provider) jointly hosted African air

navigation service providers in Senegal in 2002 to discuss the challenges facing air

navigation in the region. The focus was on the benefits of regional service provision to

reduce duplication of services, the importance of the interoperability of systems, as well

as a continued drive for the commercialisation of air navigation service providers to

ensure that aviation revenue is reinvested into aviation (ATNS, 20002).

Within that framework, in 2003, in Yaoundé, Cameroon, ASECNA and other African

service providers agreed that the concept of a single African sky should be a long term

objective that needs to be studied. It should be the result of a gradual process

comprising the following steps:

1 Harmonisation of ATM systems and procedures, including training programs.

2 Rationalisation of service areas

3 Cross boundaries cooperation between ANSPs

4 Consolidation if necessary of air navigation services, based on costs-benefits,

the elimination of discontinuities, and the necessity of a flexible system taking

into account the users needs.


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5.1.8 Training

Seminar/workshops to raise awareness about CNS/ATM techniques are provided in the

region. ASECNA has introduced courses on the new systems into the training

programme for engineers and technicians in its training centres, with the participation of

the ICAO's TRAINAIR programme (established to encourage states to use standardised

training methodology, and develop international training systems sharing). An air traffic

management training centre for air traffic controllers will be installed at ASECNA’s

training school (EAMAC) in Niamey. Fitted with an ATM simulator, it will

significantly increase ASECNA’s ability to train its controllers and permits ASECNA to

standardise its training procedures and the qualification of its controllers. In order to

improve the quality of its services, ASECNA considerably increased its training budget

between 1998 and 2004 to meet the shortage of technical staff and put the required

number of staff in place. During that period, the number of technical staff increased

from 781 to 1,116 graduates. ASECNA has already trained controllers for the

introduction of RVSM although it is not implemented yet.

5.1.9 Financing

The principle of funding of the business case is that the planned CNS/ATM

technologies for ASECNA are economically viable investments with adequate financial

returns for both ASECNA and airlines.

The life cycle of the investment is assumed to be 15 years. The total capital investment

in this case can be fully recovered through the provision of user charges. The result of

this analysis indicates a life cycle net present value (NPV5) (i.e. present value revenues

minus present value costs) of $23.5 million. The payback period, the point at which

cumulative revenues equals cumulative expenses would be 12 years from the

implementation of the plan. Both CNS/ATM and current ground-based systems were

assumed to operate in parallel during this phase of the implementation.

5 The NPV approach requires predictions of the future profiles of the annual costs and benefits associated with the implementation of CNS/ATM systems. Once all the year-by-year expenditure and benefits are established, the net benefit (benefit minus cost) for each year are calculated and discounted back to the base year in accordance with standard accounting practices.


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Sources of Financing

ASECNA has signed financing convention with different financial institutions

worldwide and Political Organizations. These include the European Bank of

Investment, the African Development Fund, The West African Development Bank, The

Central African Bank of Development, The European Union and others.

CNS/ATM demonstrations and tests are generally self-financed and sometimes financed

by subsidies from these financing structures. For the actual implementation of the

system, the agency’s usual financers (mainly European and African) indicate that they

are ready to deal with and continue the adventure with ASECNA in upgrading its

equipment to the next generation.

Cost effectiveness sequencing

ASECNA’s current charging policy is as follows: Charge for use of en-route facilities

and services managed by the agency are payable whatever are the conditions in which

the flight is accomplished (IFR or VFR) and whatever are the departure and the

destination aerodrome. Charging varies depending on the nature of the flight (national,

regional, international) and the weight of the aircraft. However, these incremental costs

(A in the Figure 5.1) are unique to CNS/ATM systems, and would not be incurred if the

systems were not implemented (ICAO, 1995). In this later case, incremental

expenditures on present technology would be required in order to continue operating the

existing system (B in Figure 5.1). These would be avoided if CNS/ATM is fully

implemented. Substantial annual expenditures are common to current and future

systems (C in Figure 5.1). These expenditures would be incurred even if CNS/ATM is

implemented. CNS/ATM costs also comprise conversion costs (D in the Figure 5.1). In

the case of ASECNA, agency will have to pass these incremental costs to users as said

previously. This means that charges will progressively increase during the life cycle of

the investment (15 years), in order to reconcile current and future revenues and

capital expenditure. The investment program amounts for about $276 million dollars

from 1995 to 2010 (235 up to 2005). Assuming that a proportionate investment will be

consented during the following ten years, and that current and future systems coexist,

users will have to bear 225 million $US from 2005 to 2020, that is to say 16.5 million

dollars per year if a margin of 10 % is taken into account. ASECNA collected about 170


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million dollars in 2004. This means that the navigation charges could potentially

increased by 9.7 per cent per year over the period6.

Figure 5.1: Classification of Costs

Source: ICAO, 1995

5.1.10 ASECNA’s implementation schedule up to 2015

Step 1: 2005 to 2010

- Progressive removal of ground based systems that are necessary to

FANS systems: HF, NDBs, VORs, DMEs, ACARS, ILS/MLS Cat 1,

Radioborne… etc.

- Progressive introduction of CNS/ATM systems

- Participation to the end of global transition plan

Step 2: 2010 to 2015

- Transition completed and FANS systems are unique to be operated. The

plan will be updated according to the technologies available

6 The payback period may be different, and probably lesser, which will increase the annual rate

C

A

D

C

B

Cost

CNS/ATMImplementation

Existing system


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ASECNA is slightly late in its implementation plans. The removal of ground based

Navaids has not started. The Agency is even reinforcing ground based navigation in

some countries. However, this is consistent with the pace of global implementation.

5.2 Analysis

The strategy depicted above clearly shows that ASECNA is aiming at tackling three

operational aspects: Safety, Efficiency and Capacity. These objectives are in line with

the industry’s requirements that have been identified and defined earlier. In fact, the

agency is fully implementing ICAO’s CNS/ATM transition guidelines.

ASECNA’s high level strategic goal appears to be the consolidation and the

modernisation of existing systems, getting the future ready by gradually introducing

CNS/ATM systems that interoperate with the conventional means, in order to be

operational when these systems will be fully required.

For Communications, the strategy is to extend VHF coverage along international

major traffic flows and inhospitable areas. The modernisation of the

telecommunication network infrastructure and systems through digitalisation is a step

towards greater data transmission and processing accuracy, efficiency and capacity.

Recent deregulation of the telecommunication markets in the region is what allows

ASECNA to implement suitable systems for its operations.

For Navigation, the agency aims at ensuring the good maintenance of existing means

during the transition phase, establishing tests beds and technological survey for satellite

based navigation, and carrying-on the implementation of WG-84 coordinates. Once

completely introduced, satellite navigation will also be used in remote airports that

actually lack instrument landing means. It potentially concerns 76 secondary airports.

Depending on the quality of ground infrastructures, and the availability of practicable

runways, this will increase their availability for operations, and could create potentials

for air travel growth. Introducing RVSM in its airspace, the agency is permitting

homogenous navigation areas between EUR CAR/SAM, ASIA/PAC and ASECNA.

More than 90 per cent of Western airlines’ aircraft will be fitted with RNP and RNAV


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capabilities (as mentioned earlier in Chapter 4) by the beginning of next decade,

whereas local airlines could not have the means to upgrade their old fleet to that level.

Hence, ASECNA is adopting a modular approach by setting up flexible ATM systems

that will be able to cope with multiple aircraft navigation capabilities. By initiating

ADS-B trials for the Atlantic Antananarivo and Dakar’s FIRs, the agency is anticipating

traffic characteristics in the EUR/SAM corridor and the Indian Ocean.

This dual strategy will certainly respond to both the needs of large and small airlines,

but this is questionable, as it is clear that it could not be cost-efficient. The fleet of

certain national and sub-regional aircraft operators is heterogeneous, and they have

limited means. There are greatest concerns about their capacity to respect the

transition schedule. A well organized transition is costly in terms of regulations,

installation, testing and training for all of the means, on the ground and onboard. Badly

organized transition is even more expensive: maintaining dual ground and onboard

installations, delay in receipt of benefits.

Equally questionable is the ability of the agency’s strategy to deliver a fully efficient

navigation system. In fact, the strategy does not suggest a desire to totally cover the

airspace, but only the most frequented routes. The rigid routes structure being

maintained, it’s obvious that the benefits that could be derived from RNP and ADS

capabilities will significantly be limited in the continental airspace.

For Surveillance, ASECNA’s strategy is to progressively install modern surveillance

technologies such as SSR-Mode S and ADS/CPDLC in each one of its ACC and where

they are mostly needed for safety reasons.

For ATM, airspace rationalisation and cross boundaries operational harmonisation of

rules and procedures are the agency’s ultimate aims. But rationalisation is oriented

towards navigation efficiency rather than capacity in term of saturation. Cooperation

with other ANSPs is limited to technical collaboration and local operational

cooperation. Airspace redesign, as suggested by the project of a single African Sky,

similar to what is being studied in Europe through the Single European Sky initiative

(Functional Airspace Blocks) is probably for the very far term.


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For Weather, the plans are to follow technology evolution and to adapt the

infrastructure accordingly.

Finally, the pan African organization intends to finance its strategy through loans from

international finance establishments and appear to have the financial backing to reach

objectives.

Figure 5.2: Possible airspace redesign in 2030

Source: CANSO, 2005

The geographical distribution of new air navigation means suggests that the agency is

not anticipating a substantial growth of air travel domestic markets for the short or

medium term. City-pairs market is insignificant (as explained chapter 1) mainly between

Central and Western Africa. Moreover, local airlines have no interest in operating these

non profitable routes, and prefer to operate the gulf of guinea corridor to improve their

load factor. Therefore ASECNA’s strategy to concentrate on main regional and trans-

regional corridors actually responds to both local and western airlines’ needs.

5.3 Conclusion

ASECNA’s strategy is coherent with the region’s needs. The dual strategy perfectly

responds to the requirement to accommodate both big and small airlines. But the cost

effectiveness of this plan is questionable: Maintaining dual equipments is costly, and

will certainly impact users’ charges.


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Dakar’s ADS system programme is two years late for example and Brazzaville’s Radar

project is also late. It is difficult to predict whether or not the Agency will fully respect

its schedule. The success depends on many factors that are not directly under its control.

Partly because the implementation of new air traffic concepts requires that member

states update their legislations, which is often a long and slow process. Moreover the

lack of means in local airlines, and the high cost of upgrading their equipments also add

to the uncertainty. It is doubtful that CNS/ATM systems will have been fully

implemented by all stakeholders in ASECNA by 2010.

However, the time frame is similar to those of other countries worldwide, and the

implementation process is more or less at the same stage as other regions like Asia.

ASECNA is even more advanced than areas like Europe on some aspects of the

programme such as airspace integration since its airspace is already integrated.

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Chapter 6: Recommendations and Conclusion

The primary objective of the thesis was to analyse the state of Air Navigation in

ASECNA area in order to find out regional needs and priorities, which responds to

the first research question. The study found that the needs are as follows.

1. Air traffic demand remains very low although the region’s economies are growing.

The growth is driving air travel demand. Moreover, real liberalization is looming,

based on the Yamoussoukro’s decision. Which is expected to boost the growth. But

that increased activity is observed on a restricted number of routes linking Europe to

main cities in ASECNA. These routes are operated by several carriers that dominate the

market.

Airlines can be divided into two groups: International airlines, and domestic carriers.

The first are mostly foreign carriers and are relatively healthy. They operate high yield

routes, possess young fleets and have a strong financial power. The second are mostly

domestic carriers, in a bad state. They operate low yield routes, their fleets are very old

and their have little financial margins. The region’s airline industry dramatically

needs to be supported by an efficient and a cost effective air navigation service to

help them to reduce their costs.

2. Fragmentation is limited in ASECNA’s airspace. The airspace is organised respond

to operational requirements. However, at a continental level, airspace is very

fragmented. Cooperation and harmonization are needed to avoid unnecessary

duplication of equipments, which is cost ineffective. The agency is leading the move

towards integration. More remains to be done to reach complete harmonisation,

particularly with the Nigerian interface.

3. Capacity appears not to be a real need in ASECNA as traffic is very low and the

airspace is very wide. But as the traffic is concentrated in a limited number of lucrative

routes, extra capacity is needed to keep efficient operations, and to maintain safety

margins in a context of growing traffic in these specific routes.

Chapter 6 Recommendations and Conclusion

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4. Safety records are extremely poor in ASECNA. Relatively to the level of traffic, the

number of air proximities, runway incursions and accidents is high, and the agency is

often engaged. But what is more preoccupying is the way the agency manages these

problems. Given the results of investigations, it can be asserted that the agency does

not have a proper safety management system to systemically process and analyse

safety data. It is rudimentary for the least. The quality, quantity and consistency of

safety data are not adequate for managing safety. A review system should be

established, providing a clear severity classification and disseminating findings.

ASECNA needs to establish such a system if it wants to improve its safety records

and restore users’ confidence.

5. Inefficiency is mainly due to the use of conventional systems. These render the

system very rigid, with fixed routes. They have operational limitations that prevent the

optimal use of the available airspace which is costly to users. These systems also have

technical insufficiencies in term of communication, surveillance and air traffic

management that degrade safety records. The agency needs to upgrade its

infrastructure to deliver a service that responds to modern requirements, in term

of systems’ availability, and data quantity, quality and integrity.

6. Cost effectiveness is good in ASECNA when compared to Europe and the USA. But

given the high proportion of staff and superfluous expenditures, the performance can be

improved, by reducing unnecessary staff in some areas with very poor traffic. That

would help to raise controllers’ productivity, and decrease support costs.

The secondary objective of the thesis was to study CNS/ATM technologies and their

relevance to ASECNA region. It responds to the second research question.

Based on the region’s geographic characteristics, and its needs presented above, the

study found that the new systems brings better efficient, increases safety margins and

capacity, enhances data processing, and allows the extension of services. They will be

cost effective on the long term, as they will help to curb the maintenance costs, and

reduce airspace fragmentation as their implementation requires international

cooperation, and a substantial level of operational and technical harmonisation on the

continental level.


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The third objective was to analyse ASECNA’s on-going modernisation strategy, to

assess whether it will respond to the needs and the priorities highlighted. It responds to

the third research question.

The agency has technical objectives to improve the current system, and to implement

future air navigation systems. Some systems have already been installed, and others are

progressively being made available to users. But the agency is confronted to the need to

accommodate both small and big carriers which do not have common interests. Given

the predominance of foreign carriers and the necessity to assist local airlines to help

maintaining an acceptable level of air service within the region, ASECNA has decided

to put in place evolutionary new systems, allowing each type of carriers to upgrade its

fleet with regard to their means and their operations.

However, the segmentation of the agencies operating revenues being overwhelmingly in

favour of transcontinental activities, the agency has chosen to firstly and

progressively equip strategic areas of routing with CNS/ATM systems and concepts.

That responds to profitability imperatives. But it does not address the immediate safety

concerns all over its areas of responsibility particularly in remote regions. The agency

is not prioritising domestic markets where most accidents occur as most of

conventional systems are maintained there.

The airspace reorganisation process that is taking place will certainly reduce unit costs.

The introduction of new systems is also expected to reduce maintenance costs. But no

study measuring the economic impact of newly introduced systems is available for the

time being.

The users will have to bear the costly equipment upgrade, and will be passed the totality

of costs of acquiring, installing and operating CNS/ATM systems. In addition, the fact

that the agency is maintaining a dual system will inflate costs. The agency has planned

to increase navigation charges by 10 per cent increase per year. That is not a cost

effective sequencing given the general state of the airline industry. In particular,

navigation charges should not inflate as the result of the introduction of new systems

because it could have a negative impact on the local airline industry. Recent

agreements between the agency and IATA that have frozen navigation charges during

the past three years suggest that ASECNA is reconsidering its charging strategy. It

shows that the agency has adopted a pragmatic policy in the interest of its users.


120

Despite limited delays in the implementation process, ASECNA has already done a

huge work to modernize its infrastructure and its procedures. Its strong financial

situation and the support of local governments and international financial institutions

guarantee that the agency will not lack means to carry on its programmes. However, the

slowness and the variability of legislation procedures and the fragmentation of

regulation authorities could generate additional delays. A key point in reaching its

objectives is how ASECNA will collaborate with states and civil aviation authorities to

speed up the process. Moreover, experts doubt that small local airlines will be able to

respect the schedule, which will delay the moment of benefits. Actually, the question is

not whether ASECNA will be able to deliver a modernised service and infrastructure to

match the needs; its local users and regional authorities constitute the real threat to the

programme.

The agency has a solid training policy, and is training air navigation staff in its own

schools to prepare the future and respond to the growing demand. That long term human

resource strategy guarantees the availability of sufficient skilled staff.

The agency cooperates with neighbouring air navigation service providers within the

framework of ICAO’s modernisation plans. A certain level of technical integration has

already been reached, in particular between ASECNA and South Africa. As the agency

is a leader in term of airspace integration on the continent, it’s coordinating

harmonization efforts.

To conclude, and in response to the main research question, it can be stated that the

ability of ASECNA to meet the needs of African Air navigation the 21st will depend on

the following key factors:

1. The respect of CNS/ATM systems’ implementation process.

2. The reconciliation of interests of major and small airlines.

3. The strengthening of ties with other African ANSPs.

4. The involvement and the commitment of member states and civil aviation

authorities.

5. And the availability of means to finance the modernisation programme


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ASECNA can help the Airline Industry reducing its costs through technology advances.

But will it be substantial? In fact, deep structural changes are required in airlines’

management practices in Africa. These necessary reforms, together with a real

liberalisation, could secure a consistent growth. Nevertheless, even deep structural

changes could only have limited impact if the demand side is not dealt with

appropriately. High air travel taxation is a common practice in the region. States should

revise that policy in the interest of economies.

Given that the programme is already well advanced, and taking into account the fact

that ASECNA’s top management is committed to modernize the agency, and to keep its

reputation as a leading and exemplary institution in Africa, it is highly probable that the

Pan African institution will make adequate technologies available to its users, although

there is no assurance that the time frame will be met. Whether states and air carriers will

be able to fulfil their obligations in term of regulations and equipments modernisation

remains uncertain. There are clear indications that they will not.

Limitations and Suggestions for further research

The contribution of this research was to give the reader an insight of an African region

rarely studied, and one of its leading organisations that tries despite numerous

environmental and structural constraints, to conduct a sound and successful strategy

towards modernisation.

However the work has several limitations. Many real-world problems were simplified

or ignored because their solutions were outside the scope of this research. Particularly,

political interferences in the management of the agency, non-harmonised civil aviation

regulations together with intrinsic social and cultural characteristics that definitely

influence the agency’s performances, are examples of research studies that could be

conducted by future students. However in a context of globalization and liberalization,

studying the impact of an hypothetic privatisation of ASECNA on the quality of service

would be a good contribution.

122

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APPENDIX 1: Presentation of ASECNA

History: An example of inter-African and Malgasy cooperation

“L’Agence pour la Sécurité et la navigation aérienne en Afrique et a Madagascar”

(ASECNA) was founded in 1959, in Senegal. It is a multinational organization,

created by 16 African countries1, 14 from Western and Central Africa, plus

Madagascar, and France. The group was joined by the Comorian Union in 2004. The

agency is presented as the best example of North to South cooperation, as well as the

structure for civil aviation excellence. ASECNA has managed to last more than half a

century because it adapted itself to the political economic context. When it was

created, ASECNA was mainly a cooperation organisation between France and

African French speaking countries and Madagascar. But years after it was founded,

the Malgasy and inter-African cooperation become Predominant. This transformation

was translated in the facts, by the transfer of the Agency’s head quarter from Paris

to Dakar, and by the “Africanisation” of the management. In 1974, the Dakar

convention was signed by the 15 countries (All the current members states, without

Equatorial Guinea who joined the organisation in 1987). The Dakar convention

remains opened to integrate any candidate country.

Mission: Air Navigation safety

ASECNA is governed by the Dakar convention, and essentially exercises community

activities in accordance with article number 2; but it also manages national

aeronautical activities, on a purely subsidiary basis, on the behalf of some individual

states and other organizations.

1 Benin, Burkina Faso, Cameroon, Central African Republic, Chad, Comores, Congo, Equatorial Guinea, Ivory Cost, Gabon, Madagascar, Mali, Mauritania, Niger, Senegal, Togo.

127

Community activities

The agency controls an area 1.5 as large as Europe. This area is divided into 6 Flight

Information Regions (FIRs): Antananarivo, Brazzaville, Dakar Oceanic, Dakar

Terrestrial, Niamey, and N’Djamena2.

It ensures the Control of air navigation flows, aircraft guidance, the transmission of

technical and traffic messages, airborne information. It also gathers data, forecasts and

transmits aviation weather information. Theses services are applied for both en route,

terminal approach and landing phases of the flights.

ASECNA ensures terminal approach aids for the 25 main airports3 of the region, as

well as 76 secondary airports. This includes airports control, approach control, ground

aircraft guidance and movements, as well as radio aids and fire protection services.

For these reasons, ASECNA has the responsibility to maintain the equipments

necessary to deliver these services, a part from the runways.

National activities

Articles 10 and 12 of the Dakar Convention allow member states to entrust ASECNA

to manage, maintain and the install of aeronautical infrastructures. Benin,

Burkina, Central African Republic, Gabon, Equatorial Guinea, Mali, Senegal and

Chad signed specific contracts with the organization under article 10.

2 These cities are respectively the capitals of the following countries: Madagascar, Congo, Senegal, Niger and Chad. The Senegalese FIR is divided into an Oceanic FIR and a terrestrial FIR. 3

Douala, Port Gentil, Mahajanga, Garoua, Malabo, Bamako, Bangui, Ouagadougou, Gao, Brazzaville, Bobo-Diolasso, Niamey, Pointe Noire, Nouakchottt, Dakar, Abidjan, Nouadhibou, N’djamena, Cotonou, Toamasina, Sarh, Libreville, Ivato, Lome.

128

The Committee of Ministers

Commission for Accounts verification

The Board of Directors

General DirectionAccounting Agency Financial Control

Organisation and functioning

Statutory structures

Organization Chart

The Committee of Ministers, composed of member states’ transport or aviation

ministers defines the general policy of the agency. It meets at least once a year. The

Presidency of the committee is revolving on an annual basis, which constitute a

problem to the efficiency of the agency.

The Board of Directors takes necessary measures to ensure the well functioning of

the organization. But above all, it appoints the accounting agent, the commissioners

for accounts verification, and the financial controller.

External representations

In Each member state, the missions of the agency are ensured by a local

representation, organised as follows:

129

External representations organization chart

The agency also has two delegations, one in Paris, and the other in Montreal;

The one in Paris (DELP) ensures essentially missions for the general direction:

- Links with aviation administrations, airlines, international organizations;

- Air Navigation fees collection

- Aeronautical information edition

- Purchase and routing of equipments

The one in Montreal represents the agency in ICAO. The delegate is member of the

international organisation air navigation commission. He participates to the work of

the air navigation experts group, and has permanent links with the ASECNA’s

member states delegations in ICAO.

Financial

ASECNA resources are essentially derived from:

• Aeronautical fees (Landing and en-route)

• Member states contributions on their national activities entrust to ASECNA

• Loans from banks, institutions and states

The agency has posted remarkable operating and net results for years, and has always

been a profitable organization.

Representative

Air Navigation Operations Aviation Weather

Radio Electrical Infrastructure Civil Engineering Infrastructure

Administration and Finances Payment services

130

Appendix 2: Ground Based Navigation Systems Principles

1 How the VOR works

Each VOR operates on a radio frequency assigned to it between 108.0 megahertz

(MHz) and 117.95 MHz, which is in the VHF (very high frequency) range. The

channel width is 50 kHz. VHF was selected because it travels only in straight lines,

resisting bending due to atmospheric effects, thereby making angle measurements

accurate. However this also means that the signals do not operate "over the horizon",

VOR is line-of-sight only, limiting the operating radius to 100 mi (160 km).

VOR systems use the phase relationship between two 30 Hz signals to encode

direction. The main "carrier" signal is a simple AM tone broadcasting the identity of

the station in morse code. The second 30 Hz signal signal is FM modulated on a 9960

Hz subcarrier. The combined signal is fed to a highly directional antenna, which

rotates the signal at 30 times a second. Note that the transmitter need not be physically

rotating—all VOR beacons use a phased antenna array such that the signal is "rotated"

electronically.

When the signal is received in the aircraft, the FM signal is decoded from the sub

carrier and the frequency extracted. The two 30 Hz signals are then compared to

extract the phase difference between them. The phase difference is equal to the angle

of the antenna at the instant the signal was sent, thereby encoding the direction to the

station as the narrow beam washed over the receiver.

The phase difference is then mixed with a constant phase produced locally. This has

the effect of changing the angle. The result is then sent to an amplifier, the output of

which drives the signal pointers on a compass card. By changing the locally produced

phase, using a knob known as the Omni-Bearing Selector, or OBS, the pilot can zero

out the angle to a station. For instance, if the pilot wishes to fly at 90 degrees to a

station, the OBS mixes in a −90 phase, thereby making the indicator needle read zero

(centred) when the plane is flying at 90 degrees to the station (Wikipedia, ).

131

VOR station; Source: ATSEEA, 2005

132

2 How DME works

The DME system has a UHF transmitter/receiver (interrogator) in the aircraft and a

UHF receiver/transmitter (transponder) in the ground station. The interrogator transmits

interrogation pulses to the transponder, which in reply transmits a sequence of reply

pulses with a precise time delay. The DME receiver then searches for two pulses with

the correct time interval between them. Once the receiver is locked on, it has a narrower

window in which to look for the echoes and can retain lock. The time difference

between interrogation and reply is measured by the interrogator and translated into a

distance measurement which is displayed in the cockpit.

A typical DME transponder can provide concurrent distance information to about 100

aircraft. Above this limit the transponder avoids overload by limiting the gain of the

receiver. Replies to weaker more distant interrogations are ignored to lower the

transponder load.

DME frequencies are paired to VHF omnidirectional range (VOR) frequencies. So

generally a DME interrogator is designed to automatically tune to the corresponding

frequency when the colocated VOR is selected. An airplane’s DME interrogator uses

frequencies from 1025 to 1150 MHz. DME transponders transmit on a channel in the

962 to 1150 MHz range and receive on a corresponding channel between 962 to 1213

MHz. The band is divided into 126 channels for interrogation and 126 channels for

transponder replies. The interrogation and reply frequencies always differ by 63 MHz.

The channel width is 100 kHz.

One important thing to understand is that DME provides the physical distance from the

aircraft to the DME transponder. This distance is often referred to as 'slant range' and

depends trigonometrically upon both the altitude above the transponder and the ground

distance from it (Wikipedia, ).

133

3 How ILS works

The ILS stations are usually installed at airports which have full traffic. Today, ILS

stations are installed in almost all ASECNA’s international Airports. ILS is used to give

to the pilot, precision information when trying to land the aircraft.

The system’s reliability depends on equipments, the quality of installations and the

environmental conditions (mountains, buildings, climatologic conditions).

There are three categories of ILS as the table below present it:

Category

I

Permits a precision approach at an altitude up to 200 feets, above the ILS

Reference point. The ILS Reference point is located about 150 metres from

the aircraft touch down point.

Category

II

Permit a precision approach at an altitude up to 100 feets, above of the ILS

Reference point.

Category

III

Permit a precision approach at an altitude up to surface of the landing runway

with no Runway Visibility

ILS stations include the followed equipments:

Localizer

Localizer is a transmitter which gives information about azimuth with regard to the

Centre Line of the landing runway. Together with the glide slope transmitter (Glide

path), a precision approach can be performed.

The localizer antennas are located at the far end of the runway. They consist on a linear

array of multi-element antennas, with thick, staggered elements. Localizers transmit

between 108 and 118 MHz.

134

Glide path

Glide path is a transmitter which gives information of the correct angle slope with

regard to the horizontal level of the straight of aircraft slide, during the landing. The

angle is 30.

ILS Marker Beacon and Compass Locator Stations

Marker Beacons are two or three transmitters which give information about the

precision approach, as control points for the aircraft, correct direction of the landing

runway extension. Marker beacons are VHF transmitters operating at 75 MHz. The

Outer Marker (OM) is used to indicate that an aircraft should intercept the glide path

when over the transmitter. The Middle Marker is used to indicate that the aircraft is at

the Decision Height (DH) for most approaches (Wikipedia, ).

4 Multilateration

A multilateration system consists of a number of antennas receiving a signal from an

aircraft and a central processing unit calculating the aircraft’s position from the time

difference of arrival (TDOA) of the signal at the different antennas.

The TDOA between two antennas corresponds, mathematically speaking, with a

hyperboloid (in 3D) on which the aircraft is located. When four antennas detect the

aircraft’s signal, it is possible to estimate the 3D-position of the aircraft by calculating

the intersection of the resulting hyperbolas.

135

Source: (Roke Manor Research, August 2005)

When only three antennas are available, a 3D-position cannot be estimated directly, but

if the target altitude is known from another source (e.g. from Mode C or in an SMGCS

environment) then the target position can be calculated. This is usually referred to as a

2D solution. It should be noted that the use of barometric altitude (Mode C) can lead to

a less accurate position estimate of the target, since barometric altitude can differ

significantly from geometric height.

With more than four antennas, the extra information can be used to either verify the

correctness of the other measurements or to calculate an average position from all

measurement which should have an overall smaller error.

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Appendix 3: WGS-1984

Source: ASECNA 1996

In 1989, ICAO adopted WGS-84 as the standard geodetic reference system for

future navigation with respect to the international civil aviation. In 1994, ICAO adopted

Amendment 28 to Annex 15.

WGS 84 is an earth fixed global reference frame, including an earth model. It is defined

by a set of primary and secondary parameters:

The primary parameters define the shape of an earth ellipsoid, its angular

velocity, and the earth mass which is included in the ellipsoid reference

The secondary parameters define a detailed gravity model of the earth.

Since January 1st 1998, geographic coordinates (latitude and longitude) are published in

term of WGS-84 geodetic reference system. Geographic coordinate obtained through

conversion to the WGS-84 system but for which the degree of original accuracy

measured in the field does not meet the specifications of Annex 11 and Annex 14, are

pointed out by an asterisk. The degree of accuracy required for civil aviation is

determined as given in Annex 11.

137

Appendix 4: ASECNA’S Telecommunications Network

138

Source: Boeing 2005 outlook

Appendix 5: Air Traffic Projected Growth by world region

139

Appendix 6 : ICAO’s Navigation SARPs

140

Appendix 7: ASECNA’s Satellite Navigation Circuits

141

Appendix 8 ASECNA’S ATS/Direct Speech Network

142

APPENDIX 9: Introduction to CNS/ATM Systems

Drivers and Origins

Background

The air transport industry has grown dramatically and rapidly, more than other

industries during the last two decades of the 20th century according to ICAO. The

organization’s statistics show that from 1985 to 1995, world air passenger travel and air

freight respectively grew at an average annual pace of 5 and 7.6 per cent (ICAO, 2002).

The annual variations worldwide are shown by the figure below. The number of aircraft

departures gained almost 45 per cent from 1970 to 1995. A projected annual increase in

traffic between 1992 and 2010 estimated that traffic would increase by about 2.5 per

cent in North America, more 4 per cent in Europe, and 6 per cent in Asia, with the rest

of the world following the same trend (Gallotti , 1999).

Annual Changes in scheduled aircraft movements worldwide

Source: ICAO, 2002

143

The picture below of a congested airspace best suggests how close some parts of the

world are to the gridlock. In some parts of Europe and North America, traffic is

restrained to preserve safety margins. Delays are growing, and this is hitting aircraft

operators’ bottom lines. On some days in the summer of 1999 European air traffic was

near to collapse. According to airlines’ representatives, delays have never been so bad,

at least not since 1959 (Spaeth, 1999, Para 2). IATA recently estimates that delays in

Europe have an annual cost of US$1.5 billion and 15 million minutes of unnecessary

flight.

instant traffic situation display over the US airspace.

Source: FAA, 2002

Elsewhere, in remote areas and over oceans, considerable improvements to ANS are

required, as the current technology has limitations. These are discussed in the next

chapter.

ICAO’s Global Implementation Plan and Monitoring

FANS Committees Work

Having considered the steady growth of international civil aviation before 1983, and

taking into account the projected growth at that time, the council of ICAO determined

in 1983 that conventional air navigation systems and procedures that were supporting

civil aviation were approaching their limits, and that time had come to develop new

144

approaches that will better suite modern air transport exigencies. In that purpose, it

established a Special Committee on Future Air Navigation Systems (So called FANS

committee).

In 1989, the FANS committee concluded that new systems had to be developed to meet

the pace of air transport development worldwide. It had also established that the

shortcomings of conventional systems could have a negative impact on the

development of air navigation almost anywhere. It also recognised that the new

systems’ objectives should be to provide a cost-effective and efficient system adaptable

to all type of operations in as near four-dimensional freedom (space and time) as their

capability would permit. The committee recommended that this had to be done at a

global scale. In the wake of these conclusions, the ICAO council established a

committee in charge the monitoring and coordination of Development and transition

planning for FANS (So Called FANS committee II).

Tenth Air Navigation Conference

In 1991, the ICAO’s tenth Air Navigation Conference (AN-Conf/10 endorsed the

FANS concept, as proposed by the ad-hoc committees. The Conference concluded

(Recommendation 1/1 – Endorsement of the global ATM operational concept) that ICAO, the

States and the regional planning and implementation groups (PIRGs) consider the global ATM

operational concept as the common global framework to guide planning for implementation of

ATM systems and to focus all ATM work development.

Theses concepts eventually came to be known as the CNS/ATM systems. In 1993,

FANS II committee concluded that the implementation of these new technologies, and

their expected benefits had to be gradual. This meant that an action plan was needed, in

order to progress toward implementation of CNS/ATM technologies and systems. The

emphasized was put on the important role states and the regions had to play, through

PIRGs, with regard to the planning and implementation processes. The Planned

evolution of the process is as shown on the following figure.

145

Evolution of CNS ATM implementation. Source: ICAO, 2002

The regional planning process

The regional planning process is ICAO’s main planning and implementation tool. A top

down approach is used, comprising a global guidance and regional harmonization

measures. This converges with the bottom-up approach formed by states and aircraft

operators and their proposals for implementation options.

Organizational and financial issues

The organizational and financial aspects in the implementation process of CNS/ATM

systems are the major challenges for the civil aviation community. Many CNS/ATM

systems are characterised by a multinational dimension, which requires an international

cooperation.

Developed states have the means to finance and develop their national CNS/ATM

plans. Australia is a good example. The implementation process is well advanced. But,

developing and poor countries (the majority of states), require assistance in many fields:

146

- Needs assessments and project development

- Transition planning

- Financing arrangements

- Systems planning, specification, procurement, installation and

commissioning

- Human resource planning and development.

Legal issues

The legal framework that governs the conduct of service providers and users is the

Chicago Convention and its annexes. Many concerns are about the Global Navigation

satellite (GNSS) that shall be compatible with international law, including the Chicago

Convention, its annexes and all the relevant rules applicable to outer space activities.

Particularly, universal access to GNSS services without discrimination, the preservation

of states sovereignty, authority and responsibility. Aircraft operators and providers of

air navigation services rely on foreign systems, as the current GNSS facilities are

controlled by one or several states (USA, EU, Russian Federation).

The continuity of GNSS services is also a matter of concern among the community, as

the state provider could decide to stop them, and force the users to rely on inefficient

conventional backup systems.

147

Appendix 10: Evolution of controllers Workforce from 2006 to 2011 in ASECNA

Centres WorkforceEnd 2005

Retirement2006

Forecastworkforce

(2-3)

Necessaryworkforce

(2007 – 2011)

Gap(4-5)

1 2 3 4 5 6Abidjan 26 0 26 35 -9Antananarivo 27 0 27 72 -45Bamako 24 0 24 35 -11Bangui 10 0 10 17 -7Bissau 7 0 7 9 -2Bobo Dioulasso

3 0 3 4 -1

Brazzaville 23 0 23 76 -53Cotonou 9 0 9 11 -2Dakar 42 0 42 104 -62Douala 23 0 23 35 -12Gao 0 0 0 4 -4Garoua 4 0 4 4 0Libreville 22 0 22 35 -13Lome 11 0 11 11 0Mahajanga 3 0 3 4 -1Malabo 8 0 8 11 -3Mopti 2 0 2 4 -2Moroni 7 0 7 11 -4Ndjamena 40 2 38 60 -22Niamey 33 0 33 76 -43Nouadhibou 5 0 5 8 -3Nouakchott 14 0 14 23 -9Ouagadougou 23 1 22 11 11Pointe Noire 6 0 6 11 -5Port Gentil 5 0 5 9 -4Sarh 2 0 2 4 -2Toamasina 4 0 4 4 0Yaoundé 8 0 8 11 -3Total 391 3 388 699 -

311

msc thesis

Documents

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air traffic management

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