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EUROPEAN ORGANISATION

FOR THE SAFETY OF AIR NAVIGATION

EUROCONTROL

Comparison of Different Workload and Capacity Measurement Methods

Used in CEATS Simulations

Comparison of SAAM 3; FTS 3, SSRTS3 and CEATS 2007 UAC Capacity

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in any form without the Agency’s permission. The views expressed herein do not necessarily reflect the official views or policy of the Agency.

REPORT DOCUMENTATION PAGE

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Security Classification: Unclassified

Originator: CRDS - Student

Originator (Corporate Author) Name/Location: EUROCONTROL CEATS Research, Development and Simulation Centre Ferihegy I. “A” kapu H-1185 Budapest - Hungary Telephone : + 36 1 2969317

Sponsor: CCRRDDSS ((CCEEAATTSS RReesseeaarrcchh aanndd DDeevveellooppmmeenntt CCeennttrree))

Sponsor (Contract Authority) Name/Location: CCRRDDSS EUROCONTROL - CRDS Ferihegy 1 "A" Kapu H-1185 Budapest HUNGARY

TITLE: Comparison of Different Workload and Capacity Measurement Methods Used in

CEATS Simulations

Authors Renée Schuen-Medwed

Date Nov2003

Pages 48

Figures 14

Tables 12

Annexes 2

References9

Distribution Statement: (a) Controlled by: Mentor (b) Special Limitations: None (c) Copy to NTIS: YES / NO

Descriptors (keywords): Model based simulation fast time simulation - real-time simulation – SAAM – FAP – RAMS – ESCAPE-Analysis- Workload-Capacity Abstract: This report presents the comparison of SAAM3, FTS3, SSRTS3 and FAP (Capacity Study 2007) focusing on workload and capacity measurements. The subject of the study is the comparison of the different objectives of the studies, different systems and methodologies and different kinds of the presenting the results. The proposals, which are made in the end, relate among other things to the used terminology.

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This document was collated by mechanical means. Should there be missing pages, please report to:

EUROCONTROL CRDS Budapest - Ferihegy 1 "A" Kapu

H-1185 Budapest Hungary

Further copies can be ordered from: [email protected]

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TABLE OF CONTENTS

1. INTRODUCTION ...............................................................................................................1

2. OBJECTIVES ....................................................................................................................1

3. DESCRIPTION OF THE METHODOLOGIES ...................................................................2 3.1 SAAM ..........................................................................................................................2

3.1.1 SHER (Sliding Hourly Entry Rate) ........................................................................2 3.1.2 Workload (Wkl) .....................................................................................................2 3.1.3 Capacity................................................................................................................3

3.2 FAP .............................................................................................................................3 3.3 RAMS..........................................................................................................................6

3.3.1 Workload...............................................................................................................7 3.3.2 Capacity................................................................................................................7

3.4 ESCAPE......................................................................................................................8 3.4.1 Workload...............................................................................................................8 3.4.2 Capacity................................................................................................................8

4 DESCRIPTION OF SIMULATIONS...................................................................................9 4.1 SAAM 3 .......................................................................................................................9

4.1.1 Traffic Sample.......................................................................................................9 4.1.2 Route Network ......................................................................................................9 4.1.3 Workload...............................................................................................................9 4.1.4 Sectorisation .........................................................................................................9 4.1.5 Flight Levels........................................................................................................10

4.2 CEATS 2007 UAC CAPACITY (FAP) ...........................................................................10 4.2.1 Traffic Sample.....................................................................................................10 4.2.2 Route network.....................................................................................................10 4.2.3 Sectorisation and FL...........................................................................................11

4.3 FAST TIME SIMULATION 3 (FTS 3) ...............................................................................11 4.3.1 Traffic Sample.....................................................................................................12 4.3.2 Route Network ....................................................................................................12 4.3.3 Controller percentage loading.............................................................................12 4.3.4 Sectorisation .......................................................................................................13 4.3.5 Flight Level .........................................................................................................13

4.4 SMALL SCALE REAL TIME SIMULATION 3 (SSRTS 3)[REF 4] .........................................15 4.4.1 Traffic Sample.....................................................................................................15 4.4.2 Route Network ....................................................................................................15 4.4.3 Workload.............................................................................................................15 4.4.4 Sectorisation .......................................................................................................16 4.4.5 Flight Levels........................................................................................................17

5 COMPARISON OF RESULTS ........................................................................................22 5.1 SAAM 3 .....................................................................................................................22 4.5 CEATS 2007 UAC CAPACITY (FAP) ...........................................................................27 5.2 FTS 3.........................................................................................................................28 5.3 SSRTS 3:...................................................................................................................30

6. SUMMARY OF THE COMPARISON ..............................................................................31 6.1. PROS AND CONS......................................................................................................32

7. CONCLUSIONS ..............................................................................................................33

8. RECOMMENDATIONS ...................................................................................................33

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8.1. TERMINOLOGY ............................................................................................................33 8.2. INPUT .........................................................................................................................34

9. ANNEX A.........................................................................................................................35

ANNEX B: SAAM WORKLOAD............................................................................................37

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REFERENCES: 1. Assessing Future ATC Capacity Requirements, A User Guide, EUROCONTROL

Capacity Enhancement ; Version 1.1 2. Capacity Plan 1999 For MAASTRICHT UAC; EEC Note 11/99; Project PLC-C-E1 3. Capacity Analysis using Model-based Controller Workload Estimation Techniques (in

RAMS v2.4) 4. CEATS Small Scale REAL-TIME-SIMULATION No.3 SSRTS 3CRDS Note No.6 Project

SIM-C; CRDS/SIM/RTS-2079-FUG 5. CEATS AIRSPACE Structure, The Third CEATS SAAM Evaluation; CEATS_SAAM

34report; Ed 1.0 6. CEATS Fast-Time Simulation No. 3; Project SIM-C, CRDS Note No. 5;Ref. No. 1240-

CRDSSIMFTS-ACK 7. CEATS 2007 Capacity Study, EUROCONTROL Experimental Centre Performance, Flow

Management Economics & Efficiency-PFE 8. Medium Term Capacity Enhancement Targets 2002-2006; EEC Note. 14/01; Project

PFE-F-FA 9. Investigating the Air Traffic Complexity; EEC Note No. 11/00; Project GEN-4-E2

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ABBREVIATIONS

Abbreviation De-Code

ACC Area Control or Area Control Centre ANSP Air Navigation Service Provider

AMNU (AFN) Airspace Flow Management and Navigation AMOC ATFM Modelling Capability ATC Air Traffic Control ATM Air Traffic Management

BADA Base of aircraft data CAPIG CEATS Airspace Planning and Implementation Group CASA Computer Aided Slot Allocation

CEATS Central European Air Traffic Services CIM Capacity Indicator Model

CRDS CEATS Research, Development and Simulation Centre CSPDU CEATS Strategy Planning and Development Unit CUAC CEATS Upper Area Control Centre

EC Executive Controller ERGO ATC Graphical Object Server EONS EUROCONTROL Open and Generic ATC Graphics System FAP Future ATM Profile

FACET Fast ACC Capacity Evaluation Tool FL Flight Level

FTS Fast Time Simulation HLT Heavy Load Threshold IPAS Integrated Data Preparation and Analysis System ISA Instantaneous Self Assessment

MECA Model for the Economical Evaluation of Capacities in the ATM SystemPACT Portable ACC Capacity Tool

PC Planning Controller RAMS Reorganized ATC Mathematical Model Simulator

R/T Radiotelephony RTS Real-time Simulation

RVSM Reduced Vertical Separation Minimum SAAM System for Assignment and Analysis at a Macroscopic Level SHER Sliding Hourly Entry Rate SIM-C CEATS Simulations Project Code SSRTS Small Scale Real Time Simulation

STATFOR Specialist Panel on Air Traffic Statistics & Forecasts TAAM Total Airspace and Airport Modeller UAC Upper Area Control Centre UIR Upper Information Region

WSME Weighted Mean Square Error

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List of Tables Table 1: FAP annual growth rates........................................................................................10 Table 2: Sectors and Flight Levels used in FTS3 ................................................................13 Table 3: Sectors in SSRTS3 ................................................................................................17 Table 4: Table of Comparison of the Simulation Studies (A) ...............................................18 Table 5: Table of Comparison of the Simulation Studies (B) ...............................................19 Table 6: Table of Comparison of the Simulation Studies (C) ...............................................20 Table 7: Evaluated sectors in SAAM 3.................................................................................22 Table 8 FAP Capacity MID FL 285+,40% ...........................................................................27 Table 9 FAP Capacity MID FL 285+, 40% ..........................................................................28 Table 10: Capacity Figures out of FTS3 ................................................................................28 Table 11: Traffic amount and ISA results out of SSRTS 3.....................................................30 Table 12: Pros and Cons .......................................................................................................32

List of Figures Figure 1 ACC nominal “zero delay” Capacity; [ref. 2] ...............................................................4 Figure 2 ACC nominal “saturated capacity” [ref. 2] ..................................................................5 Figure 3:Example of RAMS tasks [ref. 9] .................................................................................6 Figure 4: FAP sectorisation MID ............................................................................................11 Figure 5: Sector C5; C6 and C8 out of FTS3 23 Figure 6: Sectorisation for SSRTS3 .......................................................................................16 Figure 7: Evaluated sectors in SAAM 3 32 Figure 8: C5U Analyses in SAAM 3; CEATS Airspace Structure; Third CEATS SAAM

evaluation.........................................................................................................................26 Figure 9: C6U Analyses in SAAM 3; CEATS Airspace Structure; Third CEATS SAAM

evaluation.........................................................................................................................26 Figure 10: C8U Analyses in SAAM 3; CEATS Airspace Structure; Third CEATS SAAM

evaluation.........................................................................................................................27 Figure 11: Workload Measurement out of FTS3 for C5U and C6U .....................................29 Figure 12: Workload Measurement out of FTS3 for C7 and C8U/UH and C9U/UH ............29 Figure 13: Recordings of C6U out of SSRTS 3 ...................................................................31 Figure 14: WSME ...................................................................................................................36

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Executive Summary In order to harmonise the different simulation systems used in CEATS simulations a need to list all their similarities and differences became necessary. Out of that it was planned to find one methodology of workload and capacity determination which could be used for all systems. This report presents a comparison of these different methodologies for measuring Workload and calculating Capacity in CEATS sectors. The comparison includes FAP, SAAM, RAMS and ESCAPE and the appending studies and simulations using those methodologies, like SAAM 3, SSRTS 3 and FTS3. The subjects of that comparison are the objectives of the studies and systems, the used methods and the different kinds of presented results. The first statement of this study is that three of the four investigated systems are using the same workload terminology, but with different definitions. This fact causes mainly communication problems but reduces also the comparability of the results. The fourth method uses no Workload measurement but calculates the ACC capacity, which results in a Capacity demand ratio. All methods have their own characteristics and benefits explained in this report. Proposals for a unique definition of terminologies are made. Due to the fact, that all different studies are dealing with different objectives and that the systems fulfil their gains quite well, it should be mentioned that using the same methodology might not be the best practise, The harmonisation of the co-operation between the different working groups is the aim with the larger benefit in order to ensure the completion of the systems. Therefor EUROCONTROL should remain the methodologies due to their advantage. The future task is to enhance the communication between the teams dealing with these systems to gain the greatest benefit.

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Comparison of Different Workload and Capacity Measurements used in CEATS Simulations

1. Introduction The Central European Air Traffic Services (CEATS) Program was founded to co-operate in the provision of air traffic services within the upper airspace of the following countries: Austria, Bosnia & Herzegovina, Croatia, Czech Republic, Hungary, partly Italy (ACC Padua), Slovakia, and Slovenia. The CEATS planned area of responsibility is the airspace above FL 285/295. The long-term objective is to ensure maximum efficiency at minimum cost for all airspace users while safeguarding the required level of safety, and to contribute to the creation of a uniform European Air Traffic Management System (EATMS). Air traffic delays are on the increase throughout the European area. In the summer of 1998, while traffic increased by only 5.5%, ATM-related delays rose by 42.6%. Delays are expected to worsen if drastic measures for an enhanced capacity are not implemented. There is wide recognition that rationalising airspace and using all air traffic services facilities more effectively are the two main solutions to the problem. The Central European Air Traffic Services (CEATS) is the key to increasing capacity in Central Europe through the development of Air Traffic Management regional co-operation. To ensure this capacity is one of the main topics of each CEATS simulation. Therefore, this report gives an overview over different methodologies and systems used in CEATS simulations in order to take a step forward in finding the best methodology for CEATS capacity measurement.

2. Objectives This report is one part of the CEATS capacity management project. The short-term objective of this project was the comparison of different workload and capacity measurement methodologies used for CEATS simulations. This breakdown will be shown in the present report. The long-term objective of the project will be the development of a best practise for CEATS capacity measurement.

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3. Description of the Methodologies This report concentrates on SAAM (System for Air Traffic Assignment at Macroscopic level), FAP (Future ATM Profiles), Rams (Re-organised ATC Mathematical Simulator) and ESCAPE (EUROCONTROL Simulation Capability And Platform for Experimentation), which were used in the latest CEATS simulations SAAM 3, Fast Time Simulation 3 and SSRTS (Small Scale Real Time Simulation 3). Those studies were selected to compare the latest data.

3.1 SAAM SAAM® stands for System for Air Traffic Assignment at Macroscopic level. It may be viewed as a multi-functional tool, which seeks to bridge the gap between the drawing board phase of airspace planning, and the simulation of those ideas (either in fast- or real-time). One of its main uses is that it allows designers to formalise rough ideas onto a computer generated model so as to assess their impact.” One of its main objectives was to develop and evaluate proposals for future CEATS sectorisation in support to the CEATS Program. The third SAAM Evaluation studied the concrete steps of sectorisation transition-implementation in the CEATS region. In this report latest results are used and for that reason it refers to the third SAAM evaluation. (SAAM 4 was finished while writing this report). SAAM provides statistical data in form of maps and graphs, including traffic loading on individual segments of the route network and sector loads within a specified volume of airspace. So its functionality can be split into two main areas: 3D visualisation and statistical data for sector traffic loading in airspace volumes/sectors.

3.1.1 SHER (Sliding Hourly Entry Rate) SHER represents the number of aircraft entering a sector in a 60-minute period. These periods of 60 minutes are slid across each hour. The maximum value considered as acceptable for SHER was 40. In some cases a higher value of SHER was accepted for brief periods.

3.1.2 Workload (Wkl) Workload is calculated for each sector by SAAM in a similar manner to TAAM (Total Airspace and Airport Modeller). As with TAAM, SAAM workload is determined by an analytical formula that examines the relationship between the volume and complexity of traffic within a sector: Workload as computed by SAAM is a variable of 3 parameters: (see Annex B)

- No. of conflicts (C) - SHER - Average time in the sector (Avg) expressed minutes

Wkl = C*p1+SHER*p2+Avg*p3

Formula 1: Workload for SAAM

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For the purpose of the third SAAM evaluation, p1, p2 and p3 were set for a recent RVSM simulation. p1=2; p2=1; p3=2 The formula examines the relationship between the volume and complexity of traffic within a sector: In SAAM workload can be broken into four types:

- Movement* workload - Conflict Workload - Co-ordination workload - Level change workload (*No. of movements is comparable to SHER)

3.1.3 Capacity The previous CEATS SAAM evaluations used a uniform value of 40acft/hour as the maximum capacity acceptable for the sectors. FTS/2 provided the first draft capacity values to be used for the CEATS sectors and they are used accordingly in SAAM/4. The capacities determined in FTS/2 w ere not for exactly the same sectors as in SAAM/4. For the sectors with significant changes and where FTS/2 indicated a capacity higher than 45acft/hour, a default value of 45 aircraft/hour was used. This value is an average capacity for the CEATS sectors as determined in FTS/2 and it w as chosen to be consistent with the rather “optimistic” capacity values.

3.2 FAP FAP (Future ATM Profiles) identifies geographical and functional causes for delays in Europe (airports&ACCs) and allows the evaluation of macroscopic capacity plans for a planning time horizon of up to 10 years. It is a set of distributed modelling and analysing tools comprising ATFM simulation facilities as well as spreadsheet and macro based analysis and reporting tools.

• AMOC/CASA (ATFM Modelling Capability)/(Computer Aided Slot Allocation) • MECA (Model for the Economical Evaluation of Capacities in the ATM

System) • CIM (Capacity Indicator Model) • RAMS (Reorganised ATC Mathematical Model Simulator)

As this study is dealing with capacity, it is necessary to mention that two methods, based on the EUROCONTROL FAP process, are used to calculate ACC hourly capacity indicators:

- “nominal” capacity - “observed” capacity

Nominal capacity is based on the declared capacity of the sector of the ACC and observed capacity is based on actual delays observed in the ACC. Since only the nominal capacity could be applied for CEATS, this report refers to that method.

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The nominal capacity is based on the declaration of the individual sector capacities made by the ANSP to the CFMU (Central Flow Management Unit) and, therefore, this indicator reflects directly any enhancement to sector capacity and/or sector creations independent of delays generated, and of network effects or other external factors. We also have to differentiate between nominal capacity with zero delay (the traffic flow throughout the whole ACC is the maximum which can be handled without any delay) and the nominal saturated capacity. Saturated capacity means that every sector is saturated so that the traffic volume has to be increased at different levels for different flows. But at that point this report does not go into further details. One tool used in FAP project to calculate capacity is PACT (Portable ACC Capacity Tool) a PC based version of FACET (Fast ACC Capacity Evaluation Tool) enabling capacity planners to evaluate ACC capacity from declared sector capacities, for selected configurations and traffic samples. ACC capacity is mentioned here because it is a more stable indicator for medium term planning. PACT can evaluate the effect of new configurations or changes in sector capacities over the whole ACC. Using the current Air Traffic pattern over the ACC, the simulation increases the traffic volume, from its current level until one of the sectors is saturated. At this point, the traffic volume throughout this sector has reached the sector capacity. As in the following figure it is illustrated FACET simulation homogeneously increases the traffic volume from its current level until one of the sectors is saturated (declared capacity). At this point, the traffic flow throughout the whole ACC is the maximum which can be handled without causing ATFM delays; it is considered to be the Nominal Capacity with zero delay.

Figure 1 ACC nominal “zero delay” Capacity; [ref. 2]

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PACT enables ANSPs to calculate the Nominal ACC capacity indicator (zero delay) for their ACC, for any configuration. To reflect also the possibility that an ACC with one sector operating at capacity can continue to accept more traffic in the remaining sectors until every sector is saturated, the CFMU also calculates “saturated” capacity.

Figure 2 ACC nominal “saturated capacity” [ref. 2]

The “saturated” nominal ACC capacity indicator is calculated as the sum of the individual sector capacities, divided by the average number of active sectors crossed by each flight. PACT calculates the nominal (FACET) capacity indicator for selected sector configurations and traffic samples. It determines which sector configuration results in the maximum ACC capacity indicator. It determines which sector configuration is best suited to handle a given level of traffic. PACT also evaluates the effect of changes to sectorisation and/or configurations on the FACET ACC capacity indicator and it also can reduce the traffic loads that exceed the capacities in one or several sectors.

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3.3 RAMS RAMS stands for Re-organised ATC Mathematical Simulator, which reports discrete events or triggers thereby enabling the modeller to program a unique set of activities, including user-defined sets of ATC tasks and ATC participants as required, to perform a simulation study. The controller workload can be computed based on simulated sequences of discrete events:

- The flight transits an ATC sector - Various events can occur (sector entry, new flight level reaches, conflict found…) and

trigger an ATC task - Each task is allocated to the planner or tactical controller (or both), according to the

sector manning and the duties specified for each sector. - Finally, RAMS calculates the actual working time for each working position and the

percentage loading (over certain periods) on each position. The following illustration gives an example of the different types of task occurring while an aircraft transits a sector.

Figure 3: Example of RAMS tasks [ref. 9]

Flight Data Management includes not only tasks of loading, preparing and discarding flight progress strips but also computer updates. Co-ordination means external (co-ordination between centres) and internal (between sectors of the same centre) co-ordination which is recorded by the system. Conflict search: The controllers search their data before issuing clearances to ensure that the action does not endanger the separation. Routine R/T includes all the radio communication tasks. Radar tasks represent the tasks of maintaining separation of aircraft by radar actions and, when necessary, the required radar related co-ordinations with adjacent sectors.

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Rams computes controller percentage loadings, which means that the percentage of time within one hour fully dedicated to ATC tasks is recorded. The peak one hour or three hours are then used to compare the efficiency of the simulated alternatives (airspace design, test new procedures, etc.).

3.3.1 Workload The workload calculated by RAMS is the consequence of elementary controller tasks recorded during simulation. The tasks are themselves triggered by internal events, such as sector entry, conflict detection or RT communications. The computed workload remains completely dependent on the tasks definitions and their weights. The weight of a task in RAMS is nothing than its duration. To compute the controller workload a simplified formula was developed: Therefore, the workload generators can be grouped into three main families:

- Workload for routine tasks - Workload for climb and descent monitoring - Workload for conflict monitoring

Formula 2: Simplified workload formula [ref: 3]

RAMS model is able to calculate not only the actual workload on each position, which is worded as time in seconds but also the percentage loading on each position over certain peak periods.

3.3.2 Capacity RAMS defines sector capacities as a certain percentage of controller workload, usually 70% of the simulation duration (e.g. 42 minutes of work within an hour, by adding the execution times required to perform all the controller tasks). FTS3 also provided figures based on "40%" workload, which could be used as reduced capacities during the first days of implementation. RAMS used the WSME (Weight Mean Square Error) estimation algorithm to calculate capacity. The previous used algorithm was the MSE algorithm, which is based on workload and number of flights per time. The WSME algorithm uses additional to that two data the number of conflicts per time. The capacity is calculated in two steps:

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- In the first step the workload cloud W=f (F) is adjusted, in order to eliminate a certain overestimation (or underestimation). This leads to a new cloud W´=f´(F)

- In the second step, the WSME algorithm is applied to the W´=f´(F) cloud in order to estimate the sector capacity. (See Annex A)

3.4 ESCAPE ESCAPE (EUROCONTROL Simulation Capability And Platform for Experimentation) was developed for all real time simulations (RTS), ATM R&D and pre-operational (live) trials at the EEC (EUROCONTROL Experimental Centre). ESCAPE provides Off-line preparation (IPAS, BADA, EONS prep), Data repository and the online simulation facilities (EONS, ERGO, Ground, DataLink, MASS, MCS and Live Gateway). IPAS is the Integrated Data Preparation and Analysis System, which manages the airspace description, traffic sample, ATC constraints, meteorological data, architecture data, radar description and maps. Bada is the aircraft performance database and model used to provide the necessary aircraft data and operational model for trajectory calculation and prediction. The EUROCONTROL Open and Generic ATC Graphics System (EONS) provides a network-connected graphical workstation designed as a configurable ATC Graphical Object Server. ERGO component provides subjective values of controller workload in real time. The Ground module centralises the flight plan and surveillance data processing with advanced ATM features (Flight Plan data processing, surveillance data processing, safety net, medium term conflict detection feature, monitoring aids, arrival manager). The Data link module enables Air (Pilot)/Ground (Controller) communication via ATN (Data Link Initiation Capabilities, Controller Pilot Data Link Communications, Pilot Preference Down-link). MASS generates simulated aircraft data suitable for use in the simulation of surveillance system functions. EONS run time kernel interprets the interface description and manages client requests in order to create, modify and destroy graphical presentations of ATC objects on a given working position.

3.4.1 Workload ESCAPE is using ERGO (ISA) which is providing subjective values of controller workload in real time. ISA is using a scale 5ary scale from very low to very high, and the controller has to rate is subjective feeling of workload every second minute.

3.4.2 Capacity Escape is using the capacity figures of the Fast time simulation as input and evaluates those data.

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4 Description of Simulations This report describes the latest used simulations for the CEATS airspace. SAAM 3 is mentioned because SAAM 4 had not been finished at the beginning of that study.

4.1 SAAM 3

4.1.1 Traffic Sample For SAAM 3 traffic data from 1st June 2001 was used and increased by 32% for the CEATS region. It was crossed by 6366 flights. (SAAM 4 used the 28th of June 2002.) The traffic sample was created using SAAM. The process of creating the traffic sample can be summarised as follows: • From the CFMU recordings and STATFOR estimation a file is extracted containing - for

the required day of operation - all the flight plans for the flights completed; this is called „traffic demand“.

• SAAM uses only a number of initial parameters of the flights: flight ID, type of aircraft, departure time, maximum requested level, airport of departure and airport of arrival.

• The assignment is based on the following assumptions: Traffic is assigned on the latest ARN V4 route network (as endorsed by States from 29th November 2001). Traffic is assigned on the shortest route between the airport of departure and airport destination. Traffic is assigned on RVSM flight levels according to the latest AMNU RVSM harmonisation grid. Traffic reaches the maximum FL indicated in the FPL. No restrictions in LOAs are applied.

4.1.2 Route Network The third SAAM evaluation uses the latest ARN V4 route network.

4.1.3 Workload The workload indication was considered as acceptable if:

- It was not above 70 units for more than three consecutive hours and - It was not above 90 units for more than one hour.

4.1.4 Sectorisation SAAM 3 used as a baseline:

- the sectors from the second SAAM evaluation (Scenario A); - Scenario A sectors modified following some results of the CEATS Real Time

Simulation Phase 1 (Scenario B); - National sectorisation as agreed by the States for ARN V4

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4.1.5 Flight Levels The third SAAM Evaluation proposed to study CEATS airspace level opportunity (FL 285 or FL 295) required by CEATS Group of Senior Officials with reference to CEATS Agreement.

4.2 CEATS 2007 UAC Capacity (FAP) The purpose of this study was to define the 2007 baseline for capacity planning for CEATS. It was conducted using the Portable ACC Capacity Tool (PACT), one of the FAP tools and used the results of the CEATS Fast Time Simulation.

4.2.1 Traffic Sample CEATS capacity has been computed based on a 14 days sample, representative of summer 2002 traffic (07/05/2002 to 07/18/2002). This period was also used for the preparation of the ECIP for all the ECAC area. The traffic samples were extracted from CFMU archives for these 14 days. Then the flights were re-routed on ARNV4 shortest routes and optimal profiles by SAAM. Finally, this traffic was augmented by FIPS to the 2007 level, based on STATFOR baseline scenario (February 2002). So in the following FAP study the “High” and the “Baseline” grow predictions were employed Scenarios for the capacity targets for 2003-2006 were simulated by FAP based on the Baseline STATFOR forecast, as well as on the High forecast, which are characterised by the following average annual growth rates. STATFOR 2001 2002 2003 2004 2005 2006 High 6.6% 6.3% 6.2% 5.7% 5.0% 4.3% Baseline 5.4% 5.1% 5.1% 4.6% 3.7% 3.4% Table 1 FAP annual growth rates

4.2.2 Route network The augmented traffic sample was redistributed vertically over RVSM flight and horizontally over the ARN V4 route network, using the SAAM tool of the AMN Unit.

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4.2.3 Sectorisation and FL The sectorisation was derived from FTS2 and FTS3, from FL 285 to unlimited with a general vertical split at FL 345. In addition to the all CEATS (FL285+) airspace, 5 groups of sectors were simulated to prepare a possible phased implementation, with a vertical split at FL 345 and four geographical groups: • All geographical CEATS, FL 345+. • North: C1+C2+C3+C4+C7, FL 285+. • Mid: C5+C6+C8+C9, FL 285+. • Mid-South: C10+C10a+C11+C15+C16, FL285+. • Mid-West: C12+C13+C14+C14a, FL 285+.

The following map represents CEATS and the four geographical groups that were simulated.

Figure 4: FAP sectorisation MID

4.3 Fast Time Simulation 3 (FTS 3) FTS 3 wanted to determine capacity figures for the CEATS reference sectorisation taken from FTS 2 in order to include these declared figures in the FAP study, to serve for the definition of the CEATS Initial operation. Furthermore, it wanted to evaluate the sector groups for the start of Initial operations based on the CEATS reference sectorisation and CEATS sector groups.

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4.3.1 Traffic Sample FTS 3 used a 24-hour traffic sample. For Organisation A the traffic sample was taken from the 28th June 2002, increased to Initial Operation Level and aligned to the ARNV4bis route network. In Organisations B and C, the traffic sample was further increased by 100% to increase the loading to a level at which it was possible to measure more accurately. All other organisations used a traffic sample from the 28th June 2002 aligned to ARNV4bis and increased globally by approximately 32%. This equated to Initial Operation traffic levels at the start time of the study.“

4.3.2 Route Network The original traffic sample for organisation A, which was imported to the Reorganised ATC Mathematical Simulator (RAMS) from the SAAM tool, was aligned to the fixed route network ARNV4bis assigned on the shortest route, 2 D rules (arrival and departure constraints) applied as available currently in the AMNU database, no profile constraints, airport de-grouped.

4.3.3 Controller percentage loading Peak Hour Loading represents the total time spent by a working position on the tasks recorded by the RAMS simulator during the busiest 60-minute period for that position and is expressed as a percentage of that 60 minutes. The actual time of peak hours varies from one position to another. Peak hour percentage loading is used to assess the workload problems on individual working positions. Heavy Average Loading represents the total time spent by a working position on the tasks recorded by the RAMS simulator for the duration of the simulation exercise and is expressed as a percentage of that time. A peak three-hour duration is normally selected when simulation exercises exceed 12 hours. Average percentage loading is used primary to assess the balance of workload between working positions, especially in sectors with the same area of airspace being simulated. The Average Peak Workload is the average of the peak workloads given by RAMS for three consecutive hours extracted from a whole day simulation run. In order to assist in the interpretation of these loadings approximate criteria are used to describe each level as follows:- Severe peak hour in excess of 70% Heavy peak loading in excess of 55% Severe average loading (3 hour duration) in excess of 50% Heavy average loading (3 hour duration) in excess of 40% One output of FTS 3 was the Capacity Figures, which were also used for the SSRTS 3 afterwards. Therefore, the methodology will be specified here. The capacity estimation technique used in RAMS is based upon the theory that ATC capacity can be defined as the maximum number of aircraft that can enter a particular control sector in

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a specified period (one hour), while still permitting an acceptable level of controller workload. This controller workload level is known as the heavy load threshold (HLT). The Mean Square Estimation (MSE) algorithm was used in previous simulations to estimate the sector capacity, but it was indicated that capacity in certain cases was overestimated by this method. To solve this problem a new capacity estimation method has been developed. The Weighted Mean Square Error (WMSE) method is derived from the classical MSE method. The WMSE algorithm affects a weight, proportional to the number of conflicts observed during specified time periods to each workload computed by RAMS in the same time periods. (See ANNEX A)

4.3.4 Sectorisation Same sectors as in FTS 2 Org C and Org D were used for FTS 3. This CEATS sectorisation was based both geographically and vertically on FTS1 results, which used the CEATS airspace structure of the 1st CEATS SAAM evaluation.

4.3.5 Flight Level This report is referring to organisations B (lower limit of flight level 285) and C (lower limit of Flight Level 345) of FTS 3. Both B and C have the same sectorisation as organisation A. U H C5 285-355 355-999 C6 285-355 355-999 C8 285-355 355-999 Table 2: Sectors and Flight Levels used in FTS3

For that comparison just the lower level sectorisation was used concerning the objective of comparing those four systems. On that basis, FTS 3 and SSRTS 3 were using the following sectorisation: FTS 3: This report is just focusing on the results of the coloured sectors referring to SSRTS 3.

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Figure 5: Sector C5; C6 and C8 out of FTS3


4.4 Small Scale Real Time Simulation 3 (SSRTS 3)[ref 4] The SSRTS 3 simulation was designed to evaluate the interface co-ordination between the CUAC sectors and the subjacent and adjacent airspace including the civil-military co-ordination. In the simulated environment there were three CEATS sector, three national measured sectors together with one co-located military unit.

4.4.1 Traffic Sample The civil traffic samples were recorded on the 28.06.2002 and were also used for SAAM4 and FTS 3 simulations. The traffic level used in the SSRTS 3 simulation was in accordance with the capacity figures determined in the FTS 3 simulation. The civil traffic level was modified in certain sectors in order to be able to simulate the average daily peak level for each sector at the same time. National experts tested all the traffic samples for this simulation. The simulated traffic level, distribution and flow were at the required level to evaluate the SSRTS 3 simulation objectives. The baseline traffic represented various periods of daily traffic. Four different periods of daily traffic were selected and simulated, including the typical traffic distribution in the measured sector from morning until evening.” For SSRTS 3 the base line traffic was subsequently increased to create various periods of the daily traffic appropriate to the simulation objectives, including the typical arrival and departure flow of the simulated area. The military samples were prepared for a normal daily activity and for a typical military exercise day.

4.4.2 Route Network The CEATS SSRTS 3 traffic samples were aligned to the fixed route network environment (ARN V4 bis).

4.4.3 Workload The Instantaneous Self-Assessment (ISA) method was used to assess controller workload. The participants were asked to respond to a prompt every two minutes by pressing one of five buttons appropriate to their perceived workload at that moment: Very Low, Low, Fair, High or Very High. The definitions of these ratings are as follows:

1. Very Low: The controller has little or nothing to do.

2. Low: The controller has more time than is necessary to complete the tasks. The time

passes slowly.

3. Fair: The controller has enough work to keep him/her stimulated. All tasks are under control.

4. High: The controller is working “at the limit”. Certain non-essential tasks are postponed.

Time passes quickly.

5. Very high: The controller is overloaded. Some tasks are not completed. The controller feels he/she is not in control.

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All ISA-responses were visible on-line at the simulation supervisor desk during the conduct of the simulation. All responses were also recorded for later statistical treatment. For every individual controller position, it could be seen at which time which button was pressed.

4.4.4 Sectorisation The simulation area comprised the middle part of the CEATS UIR. Out of the three CEATS civil sectors in this simulation only one was a cross-border sector (C6U). The military sector coincided with the national airspace of Austria.

C8U

C5U

C6UB5

Sout

North

CEATSC5U; C6U; C8UNational

GND-B5; North;

LJLJ

EDDM

LKTB

LJMB

LOWI

LOWK

LHBP

LHTA

LOWW

LOWL

LOWS

LOXZ

LOAV

LZIB

LOWG

Figure 6: Sectorisation for SSRTS3

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4.4.5 Flight Levels Thus, this report is just concerning the CEATS sector with the base level 285, the national sectors were not considered.

Measured Sector Table

Sector Name Sector Code Category Vertical

Limits No. CWP

CEATS 5 Upper C5U Civil Area En-route FL285-345 2



National Bravo 5 B5 Civil Area En-route

GND*-FL285 2

National North N Civil Area En-route

GND*-FL285 2

National South S Civil Area En-route

GND*-FL285 2

Austrian co-located OAT Unit CMAT

Military Area En-route

GND-UNL 2

Table 3: Sectors in SSRTS3

All the different inputs and the different methodologies are listed in the table below.

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Table of comparison:

Simulation/ Factors

Objectives Traffic Sample Route Network Flight Levels ATC Tasks

SAAM 3

Evaluate traffic demand in CEATS sectors GND-FL285 Propose possible merging of national ACC respecting SHER and workload criteria Evaluate traffic demand in CEATS sectors above FL 345 and in national sectors GND – FL345

1st of June 2001; increasing 32% for CEATS sectors; ARNV 4 (RVSM) Up to 345 and from

345

CEATS 2007 UAC Capacity (FAP)

Define the 2007 baseline for capacity planning for CEATS; 14 days in summer 2002 ARN V4 285+; 345+ None

FTS 3 (FAP; RAMS)

Determine Capacity figures for CEATS; Evaluate sector groups; Evaluate controller workload for the EC and PC Evaluate sector opening hours,

24 hour traffic; 28.06.2002 increasing 32%. In org. B and C it was increased 100% for capacity.

ARNV 4bis Lower limit FL 285; lower limit FL 345

Flight Data Management Co-ordinations Conflict search Routine R/T Radar Tasks

SSRTS 3 (ESCAPE)

Verify and evaluate a typical sample of the CEATS UAC interface with subjacent and adjacent airspace. To test and evaluate the CUAC co-ordination procedures with non-CEATS sectors. Further evaluate the CUAC internal ATC procedures.

28.06.2002 increasing 32%; baseline: various periods of daily traffic

ARNV 4bis

FL 285-345; and national sectors FL 120 (civil traffic) – FL 285 (And restricted areas)

Flight Data Management Co-ordinations Conflict search Routine R/T Radar Tasks

Table 4: Table of Comparison of the Simulation Studies (A)

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Simulation/ Factors Simulated (evaluated) sectors Workload Measurements Complexity Factors Formula

SAAM 3

National Sectors N/285; CEATS Sectors A/285; CEATS Sectors B/285 National sectors N/345 CEATS Sectors A/345 CEATS Sectors B/345

Workload: Movement workload; Conflict workload; co-ordination workload; Level change workload; Maximum value considered as acceptable for SHER was 40was considered as acceptable if it is not above 70 units for more than three consecutive hours, and if it is not above 90 units for more than one hour

Wkl: C*p1+SHER*p2+Avg*p3 p1= 2 p2=1 p3=2

CEATS 2007 UAC Capacity (FAP)

C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C10a, C11, C12, C13, C14, C14a, C15, C16

None None Capacity/Demand

FTS 3 C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C10a, C11, C12, C13, C14, C14a, C15, C16

1-hour peak loading, 3-hour peak loading Workload = Workload of routine tasks + Workload for climb and descent monitoring + Workload for conflict monitoring Severe peak hour = in excess of 70%, Heavy peak loading = in excess of 55%, Severe average loading (3 hour duration)=in excess of50%,Heavy average loading (3 hour duration)=in excess of 40%

vertical traffic complexity (cruise, climb and descent); horizontal traffic complexity (entry/exit points, crossing points)

WSME algorithm WL=ωR*ncros+ω Vert*n Vert +ωConf*nConf

SSRTS 3 (ESCAPE) C5, C6, C8, Austrian National sectors: S, N, B5 ISA

vertical traffic complexity (cruise, climb and descent); horizontal traffic complexity (entry/exit points, crossing pointsmilitary traffic

1= under-utilised; 2= relaxed; 3 = comfortable; 4=high; 5= excessive

Table 5: Table of Comparison of the Simulation Studies (B)

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Simulation/ Factors Analyses/Output

SAAM 3

MAPS No of flights on route network points; Route network segments; airspace volume, sector groupings Sector load;

CEATS 2007 UAC Capacity (FAP) Capacity demand ratio;

FTS 3 (FAP; RAMS) Occurrence of each task; number of sector entries; number of FL crossed; Number of conflicts Route charge; controller loading**; sector opening

SSRTS 3 (ESCAPE)

Analysis of Traffic; Analysis of Separation loss; Analysis of Performance; Telephone Communication; Radio Communication; Pilot orders; HMI tools usage; ISA analysis, analysis of the sector design

**: total time spent by a working position on the tasks recorded during the busiest 60-minute period (during the busiest 3-hour period)

Table 6: Table of Comparison of the Simulation Studies (C)

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5 Comparison of Results To compare the results, the different objectives of each simulation-methodology and tool must be taken into account. This report will just focus on the capacity and workload analysis for the sectors C5, C6 and C8 because they were used in all three simulations. The Top sectors are not taken into account because it was not simulated at SSRTS 3.

5.1 SAAM 3 The SAAM evaluation was a kind of basis for the other simulations. It tried to deliver the graphical representation of the CEATS sectors overlapped with national sectors underneath. SAAM specified Sectorisation A/285 – CEATS base FL 285 and Sectorisation A/345– CEATS base FL 345. Sectorisation B means that there are modifications at the sectors C10, C12, C13 and C14. Thus, at that report just C5U, C6U and C8U are compared sectorisation B is not taken into account for that report. So just flight level 285 to 345 has to be considered. SECTOR NAME SAAM 3 U up to T from C5 345 345 C6 345 345 C8 345 345 Table 7: Evaluated sectors in SAAM 3

The output of SAAM was taken as a basis for following simulations, but concerning the results especially of the real time simulation the sectorisation for C6 and C8, even after changing the sector shapes a little bit, are not the optimum and should be improved.

22

Com

23

parison of Different Workload and Capacity Measurements used in CEATS Simulations

Figure 7: Evaluated sectors in SAAM 3


Initially left blank

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The workload measurement of SAAM 3 is just an objective one and is still under development. This should be mentioned if the values of the C6U are interpreted as to be higher then C5U and C8U. Again, the sector shape and the route network should be taken into account comparing these results. In this case Workload is calculated including SHER, Average time and No. of conflicts. So it is just an objective measurement. The workload indication was considered as acceptable if

- It was not above 70 units for more than three consecutive hours and - It was not above 90 units for more than one hour.

Figure 8: C5U Analyses in SAAM 3; CEATS Airspace Structure; Third CEATS SAAM evaluation


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As can be seen out of the formula [formula 1], described in chapter three, workload is just measured for the sector and no distinction is made between the controllers working positions (Planner, Executive). Also ATC tasks are not taken into account. As already has been mentioned workload is just calculated out of SHER, the number of conflicts and the average time in the sector.

4.5 CEATS 2007 UAC Capacity (FAP) Referring to RAMS the FAP study calculated with 70% and 40% capacity. The following table presents CEATS capacity given by PACT, as well as the demand (peak1 and peak3). To stick again to CEATS sector C5, C6 and C8 it should be focused on sector C6 FL 345+ as a bottleneck with capacity 27 and demand 30, and to the scenario MID 285+ in the FAP study which includes C5, C6, C8 and C9 Capacities MID FL 285+, 70%

Week day Week-end Average 14 days

Capacity (PACT) 140 151 143

Peak 1* 103 109 105

Peak 3** 89 94 91

* Peak 1: Maximum hourly demand of the day ** Peak 3: Average hourly demand of the three consecutive busiest hours in the day

Table 8 FAP Capacity MID FL 285+,40%

The capacity found for this part of CEATS is sufficient to handle the demand, with a capacity demand ratio of 1.57. Capacities MID FL 285+, 40%

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Week day Week-end Average 14 days

Capacity (PACT) 79 86 81

Peak 1* 103 109 105

Peak 3** 89 94 91

* Peak 1: Maximum hourly demand of the day ** Peak 3: Average hourly demand of the three consecutive busiest hours in the day

Table 9 FAP Capacity MID FL 285+, 40%

With the reduced capacity, there would be a shortfall and delays in 2007 (capacity demand ratio equal to 0.89).

5.2 FTS 3 Following table shows the result of the capacity calculation done by RAMS. SECTOR FTS3 Capacity (A/C per hour) C_5U - FL285 - FL355 50 C_5UH - FL355 - FL999 50 C_6U - FL285 - FL355 49 C_6UH - FL355 - FL999 46 C_8U - FL285 - FL355 50 C_8UH - FL355 - FL999 49

Table 10: Capacity Figures out of FTS3

These capacity figures were used as input for SSRTS 3 and FAP. Concerning the definition of Capacity used for RAMS, “Capacity is the maximum number of flights which can enter a sector within a specified time period and still permit an acceptable level of controller workload.” Results of the workload analyses should be reflected, too. For the comparison of the results Organisation D was extracted out of RAMS. The workload was measured as the percentage of working on the sector during a 1-hour peak and a 3-hour peak.

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Again, just the results of the sectors C5U, C6U, and C8U are abstracted.

0

510152025

303540

%Workload

C_5U C_6U

Controller 1hr / 3hr Peak Workload

PC 1 hrEC 1 hrPC 3 hrEC 3 hr

Figure 11: Workload Measurement out of FTS3 for C5U and C6U

Chart 11 above shows the peak % loading for the PC and the EC over the 1hr and 3hr peak workload periods in sectors C_5U and C_6U, where the CEATS base is FL 285.

Figure 12: Workload Measurement out of FTS3 for C7 and C8U/UH and C9U/UH

Chart 12 above shows the peak % loading for the PC and the EC over the 1hr and 3hr peak workload periods in sectors C_7, C_8U, C_8UH, C_9U and C_9UH, where the CEATS base is FL 285.

In order to assist in the interpretation of these loadings approximate criteria are used to describe each level as follows: Severe peak hour in excess of 70% Heavy peak loading I in excess of 55% Severe average loading (3 hour duration) in excess of 50% Heavy average loading (3 hour duration) in excess of 40%

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As can be seen from the above charts, the unbalance of workload between the EC and PC is quite significant with, in the vast majority of sectors, the EC having approximately twice as much workload as the PC. With these levels of traffic most of the sectors recorded less than 40% for each controller, which is moderate workload. Comparing C5U, C6U and C8U, it can be seen that the loading in sector C6U of the executive controller over the 1hr peak and the 3hr peak is the highest. Whereas the loading values for the planning controller are the highest in C5U.

5.3 SSRTS 3: Following table shows the analyses concerning the numbers of aircraft and the workload for each sector and each position in SSRTS 3 MEAN\Excercises

AUT 1 AUT 1B AUT 2 AUT 2B AUT 3 AUT 3B AUT 4 AUT 4B RAMS cap figures

C5U Total # a/c 47 49 47.5 42.5 62* 61.8* 56* 40 50 C5U Mean # a/c

1.26 1.29 1.27 1.11 1.67 1.65 1.47 1.57

C5U Max # a/c 4 5 4 5 5.67 5 5 5.67 C5U ISA ec 2.56 3.1 3.03 2.2 2.33 2.61 1.67 2 C5U ISA pc 1.77 2.52 2.81 1.84 2.61 2.59 2.15 1.55 C6U Total # a/c 33.5 31 41.5 36.5 47.33 51 45 29 49 C6U Mean # a/c

0.89 0.82 1.11 0.95 1.28 1.3475 1.18 0.85

C6U Max # a/c 3 3 5.5 3.5 5.33 5.25 5 3.67 C6U ISA ec 1.92 2.65 2.19 1.775 2.67 2.625 2.45 1.79 C6U ISA pc 1.625 2.23 2.65 2.33 2.40 2.355 2.42 1.74 C8U Total # a/c 35 37 39.5 42 45.67 43.5 45 26 50 C8U Mean # a/c

0.93 0.97 1.06 1.12 1.23 1.17 1.18 0.81

C8U Max # a/c 4 4 4 3.5 5.33 4.75 4 2.67 C8U ISA ec 2.39 2.19 1.71 2.39 2.81 2.72 2.82 3.01 C8U ISA pc 2.06 1.32 2.45 1.815 2.35 2.62 3.39 2.12 1= under-utilised; 2= relaxed; 3 = comfortable; 4=high; 5= excessive AUT 1= low traffic amount; AUT 4= high traffic amount; B=changes in the military activity, high exc wkl.; high pc wkl

Table 11: Traffic amount and ISA results out of SSRTS 3 *At this point it has to be mentioned that there was a lot of military activity in sector C5U and that this fact might be the reason why there were more flights counted. So if a military aeroplane did an aerobatic flight left the sector and entered the sector after the aerobatic exercise or during that it was not possible for the system to notice that. It also must be mentioned that that the number of aircraft was recorded by the controller positions and not by the pilot positions. Even if controller mentioned during interviews made after some exercises not to be satisfied with the sector shape this effect is not shown in the workload measurements. If just those factors are considered it seems that the controllers favour the capacity figures, which keeps their workload at an acceptable level. The analyses pointed out higher workload in C5U and C8U than in C6U.

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The following chart shows an example for other collected data.

C6U

0

5

10

15

20

25

2 8 14 20 26 32 38 44 50 56 62 68 74

time

"eve

nts"

COORD_COUNTCOORD_DECCOORD_ACCCOORD_SENDSTCA_COUNTDIRECT_COUNTHEADING_COUNTSPEED_COUNTXFLS_COUNTCFLS_COUNTTOTAL_TRANSFERREDTOTAL_ASSUMED

Total number of a/c

Figure 13: Recordings of C6U out of SSRTS 3

6. Summary of the Comparison As this report is just focusing on workload and capacity factor, once again, a summary of the comparison of those four (SAAM, RAMS, ESCAPE; FAP) systems is given. Different objectives should be taken into account. INPUTS:

- FTS 3 and SSRTS 3 used the same traffic sample (28th June 2002) - FTS3 and SSRTS 3 used ARNV4bis - FTS3 used sectorisation of FTS 2 (in series of SAAM) for SSRTS 3 sectors were

changed a little bit - FTS 3 , SAAM 3 and SSRTS 3 were using/evaluating the same FL, just the level to

the national sectors were different - FTS 3 and SSRTS3 were measuring the workload on each controller working position

(EC/PC) - SSRTS 3 used the same capacity figures as FTS3 - The workload measurements of the three methodologies differ a lot. - CEATS 2007 UAC Capacity:14 days traffic sample with “High” and “Baseline”

predictions; ARNV shortest routes and optimal profiles by SAAM OUTPUTS:

- SAAM3: Maps, Sector load graphs; sector grouping map, sector workload - FTS3: capacity figures; controller loading (both working positions), route charge

service units, sector opening hours (respective to the simulated flight levels) - SSRTS3: general results on the interface with subjacent and adjacent sectors; results

concerning co-ordination; sector design; HMI aspects; workload results (both working positions); results of the recorded tasks in comparison with the number of a/c.

- CEATS 2007 UAC Capacity: Capacity/Demand ratio for ACC level

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6.1. PROS and CONS After comparing the different systems and methodologies an analysis of Pros and Cons were made. SAAM can be seen as a basis for all other simulations, which then use the SAAM sectorisation. The workload measurements of SAAM are still under development and differ so far from the workload measurement used in SSTR3 and even from the workload measurement used in FTS 3. SAAM was just measuring sector workload whereas FTS3 and SSRTS3 were measuring the controller’s workload on each working position (pc and ec) The controller loading in FTS 3 was very high for C6U (again just C5U, C6U and C8U compared). This was not visible in SSRTS 3. One reason for that might be the capacity figures and the traffic amount- which were not exactly the same as in Fast Time Simulation 3- used in the real time simulation. It also has to be reminded that the workload measurement used in SSRTS3 was a subjective one.

Pros ConsSAAM 3 Basis for sectorisation Airspace modelling,

very quick appropriation of dataJust the sector workload is evaluated, (simpleworkload measurement)macroscopic tool

FTS 3 Route charge; capacity figures; sectoropening hours;Ideal process, both positions (pc and ec)are measured

Tasks (not defined accurately), Conflicts

SSRTS Real Time SimulationTypical daily loadNo standardised processingHuman Factorsboth positions (pc and ec) are measured

Number of simulated sectors,No standardised processing;Human Factors (attitude)

PACT Proposing a baseline for CEATS capacity,delay prediction

No extra workload measurements, no HF;macroscopic level; ACC capacity

Table 12: Pros and Cons

As listed above, human factors can be a positive point as well as a negative point. The attitude of the controller towards the system and the project is very important and influences the results. On the other hand, as seen in the FTS 3, an ideal scenario is development without the “disruptive factor” human being. Due to the fact that SSRTS 3 is a real time simulation it has to be mentioned that the non-standardised procedures are a positive point, on one hand, because controllers' demands can be satisfied, on the other hand, it is very difficult to compare results which were collected in a non-stable environment. Another positive point of the real time simulation is, of course, the possibility to simulate the daily load of the airspace, but it is not possible to simulate peak loadings. The negative point of a real time simulation compared with the Fast Time simulations is the limited number of simulated sectors and the costliness. Pact has to be seen different focusing on its objectives as a more macroscopic tool for medium term capacity planning.

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7. Conclusions All three (Pact is not using Workload) methodologies are using the term “Workload” for completely different measured factors. To compare that, the methodologies should either conform to each other or should define different terms, for example for subjective workload measurement and objective measurement. For all four systems it should be focused on their objective and they are complementing one another in a satisfying way. SAAM is a good basis for the other simulations and the results can be used in other model-based tools (RAMS; TAAM; PACT) FTS 3 is delivering an ideal of the results, which have to be validated by a real time simulation. For the real time simulation the controllers should be trained all to the same level for all sectors and all airspace, so that the disruptive factor “bad knowledge of the airspace”, which for sure influences the results, can be excluded. For the validation of the fast time simulation all factors and data which were collected there should also be collected in the real time simulation under the same circumstances. FAP has to be mentioned extra as it differs from the other systems providing a more macroscopic indicator for medium term capacity planning. FAP is calculating in contrast to the others, which are calculating sector capacity, ACC capacity.

8. Recommendations

8.1. Terminology Referring to literature one recommendation of this report is to differentiate between Taskload, Workload and Sectorload.

Taskload:

Duration of the task, which a controller has to perform to fulfill his job.

Workload:

Strain as a result of taskload, experience, ages, daily conditions and work environment.

Sectorload:

The number of aircraft including the geometry of the sector and the characteristics of the

route network.

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The advice of the author is to use the term taskload and sectorload in Fast Time Simulations and Workload in Real Time Simulations. This should make comparison in future much easier.

8.2. Input Following recommendation treats with the data which should be used for different studies. Taskload: Tasks:

- Flight data management - Co-ordination between ATC units - Conflict search - Routine R/T - Radar Tasks

Workload:

- Subjective Measurement Capacity:

- Workload/Taskload/Sectorload - Airspace figures (intersecting routes…) - Complexity factors (influencing the workload of the controller)* - Number of aircraft’s

*SAAM is going to implement the sector complexity indicators, which are developed by EUROCONTROL/PRU next year into the SAAM studies. At CRDS at the moment two studies are carried out: “Study on factor affecting controller workload in FT Simulations” done by Carla Müller and “Differences in capacity and workload between different types of ATC simulation” done by Mara Ćujić These studies are dealing with factors and tasks affecting workload (taskload) and the implementation of those factors in Fast Time Simulations.

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9. ANNEX A Workload calculation in RAMS: The MSE method uses two data: the Workload (W) per Time and the Number of Flights per Time (F). The WMSE method uses, in addition to these two data, the Number of Conflicts per Time (C). In this method, the sector capacity corresponds also to the Heavy Load Threshold (HLT) of the estimated curve W= f (F). The method described below calculates the capacity in two steps: • In the first step, the workload cloud W= f (F) is adjusted, in order to eliminate a certain

overestimation (or underestimation). This leads to a new cloud W’= f’(F) • In the second step, the WMSE algorithm is applied to the W’= f’ (F) cloud, in order to

estimate the sector capacity. 1. Workload adjustment The workload calculated by RAMS is the consequence of elementary controller tasks recorded during simulation. The tasks are themselves triggered by internal events, such as sector entry (#SE), conflict detection (#CF) or RT communications. As Users are free to define for themselves the list of tasks related to a certain controller of a certain sector, the computed workload remains completely dependant on the task definitions and their weights. The weight of a task in RAMS is nothing than its duration. Particularly, if events and/or tasks of a certain type (for example cognitive or mental tasks) are missing, the workload may be underestimated. The Users are offered the possibility to adjust (modify) the workload point cloud (W= f (F)) by the following transformations: W’ = (1+m) * W+ n … (1) Where, m is the margin (in %) to take, for Safety reasons, for workload assessment by a fast time simulator (in our case RAMS). It is a correctional percentage applied to each point of the cloud W= f (F). Normally, m cloud be positive or negative. Note that the coefficient m increases (or decreases) the workload with an amount proportional to the workload value. n means that the controller might be loaded (with n%) during a period of an hour, even if no traffic is observed during that period. This value is equal to zero in the current MSE RAMS capacity estimation method. n takes the same unit than the workload (W’), it could be expressed in % or in minutes.

42 minutes 18 minutes How parameters m and n are chosen in practice? In practice, the parameters m and n are given respectively m=+5% and n=3 minutes. This means that the initial workload values arise with 5%. This is equivalent to the assumption that RAMS underestimates the workload with a relative error of 5%. n=3 minutes means we assume that, without traffic, a controller has a workload of 3 minutes during one hour of work,

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which is reasonable, even if this value may depend on sectors. In practice, Users may change the m and n parameters, according to the scenario data. 2. The WMSE estimation algorithm The MSE algorithm (2) is based on the assumption that each point of the cloud W= f (F) has the same weight, for example p0=constant, as the minimisation criteria could be written: N 2 Min ∑ p0 [f (Fi) – f’ (Fi)] …(2) i=1 in the WMSE algorithm, points of the cloud W= f (F) are affected different weights pi, i.e. relation (2) becomes: N 2 Min ∑ p [f (Fi) – f’ (Fi)] …(3) i i=1 as in the real ATC world, the sector capacity is fixed according to high level workload figures.

0

10

20

30

40

50

60

70

80

0 10 20 30 40 50 60 70 80 9

Number of Flights

Con

trol

ler L

oadi

ng

77

HLT

64

0

Figure 14: WSME

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10. ANNEX B: SAAM Workload Interpretation of the Sector Load Graphs SAAM© stand for System of Air Traffic Assignment at Macroscopic level. SAAM is a multi- functional tool developed within Airspace Management and Navigation Unit of EUROCONTROL. SAAM evaluations are normally required to close the gap between the drawing board phase of airspace planning and the simulation of those ideas (either in fast- or real-time). SAAM is mainly used to macroscopically analyse in a time- effective and a cost-effective manner various airspace scenarios and transform these scenarios onto computer generated models in preparation for their simulation SAAM functionality can be split into to main areas: 3 D-visualisation and statistical data for sector traffic loading in airspace volumes/sectors. The graphs presented for the various scenarios may be read as follows:

As with TAAM, SAAM workload is determined by an analytical formula that examines the relationship between the volume and complexity of traffic within a sector.

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Workload as computed by SAAM is a variable of three parameters:

These parameters are then pondered, the results being a combination of them as follows:

P1, p2 and p3 are constants, set for the third SAAM evaluation: p1=2, p2=1 and p3=2 Important: In order to better approximate the conflict calculation (which is heavily influenced by a change in the departure time), SAAM is applying 10 perturbations to the departure time of the traffic the end result being an average of the ten conflicts counts made

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