rnav system requirements for airplanes
DESCRIPTION
RNAV in Europe - Procedure Design Master ClassRNAV System Requirements (1) FMS database issues FMS architecture FMS database production What RNAV can do FMS limitationsEUROCONTROL Aircraft owner Aircraft manufacturer FMC manufacturer Database supplier1RNAV in Europe - Procedure Design Master ClassRNAV System Requirements (2) Navigation Performance Accuracy, Integrity, Availability & Continuity Need for accurate data in WGS 84 Need for appropriate toolsEUROTRANSCRIPT
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
1
RNAV System Requirements (1)
• FMS database issues• FMS architecture• FMS database production • What RNAV can do• FMS limitations
• Aircraft owner• Aircraft manufacturer• FMC manufacturer• Database supplier
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
2
RNAV System Requirements (2)
• Navigation Performance• Accuracy, Integrity, Availability &
Continuity• Need for accurate data in WGS 84• Need for appropriate tools
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
3
RNAV System Requirements
FMS Architecture• System Architecture
• Main elements:• Flight Management Computer(s)
• Control Display Unit
• Navigation Display
• Navigation sensor (mix)
• Additional elements• Update sensors (DME/GPS/IRS)
• Navigation database
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
4
RNAV System Requirements
FMS Database production• Every 4 weeks a new navigation database• Double cycle system: old and new version stored and
retrievable by the crew• Navigation data provided by the database supplier• Non tailored (AIP) and tailored (company routes) data
compiled• Engine and Airline Policy data added and navigation
data • Update closes 2 weeks before the effective date
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
5
RNAV System Requirements
FMS Database production (2)
• Diskettes produced by the FMC manufacturer (Honeywell) or licensee (Racal/Jeppesen)
• changes checked by the navigation database diskette producer
• Shipment of navigation diskettes/data-transfer to the Aircraft Operator
• Data available ~1 week before the effective date• Loading via Nav Database loader before the effective
date
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
6
RNAV System Requirements
FMS Database production (3)
• Nav Database capacity• 96 Kb/192Kb/500Kb/1Mb/........
• Nav Database structure• Sub-files:
• Airways• Navigation facilities (ILS/VOR/DME/NDB)• Way points• Airports• Runways• Gate positions• TMA procedures
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
7
RNAV System Requirements
FMS Database production (4)
• Coding rules according AIRINC 424 specification
• Path and Terminator concept• Flight paths normally designed for non RNAV
aircraft• ~20 different ‘tools’ for ‘translation’ of written text for
coding the flight path• Complex routes >>>Complex coding• TMA procedures consumes half the database
capacity
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
8
RNAV System Requirements
FMS Database production (5)
• At present, responsibility for coding rests with the database supplier
• Future: coding advise by the State Authority?
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
9
RNAV System Requirements
What RNAV can do (1)
• Highly accurate lateral navigation during straight segments when within Radio update mode
• Assistance in vertical navigation• Certified VNAV control emerging• Random tracking• Smooth track intercepting
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
10
RNAV System Requirements
What RNAV can do (2)
• Controlled turn• RF leg is emerging, but will not give all answers
to the open loop turn problems
• Fly-by turn • FMS-friendly, but requires significant freedom to
start and end the turn
• Fly-over turn• Unstable intercept next leg• Requires long stabilisation distance
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
11
RNAV System Requirements
FMS limitations (1)
• Minimum distance between waypoints• Limitations for SID coding (often tight turns desired)• Speed control required (dominant factor)• Speed control may affect aircraft performance
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
12
RNAV System Requirements
FMS limitations (2)
• Limitations direct after take-off• First fly-by way point minimum distance from
Departure End of the Runway (DER)• Turn delay when fly-over is programmed• Turn delay when turn at an altitude is
programmed• Destabilised route in case of fly-over coding,
unless DF leg is applied
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
13
RNAV System Requirements
FMS limitations (3)
• Limited in general speed constraints• Only one general speed limit per airport (e.g
250 kt below 10.000 ft)
• Limited in procedure designation• Only one approach type per runway codable
(unless officially designated separately)• Only one missed approach per approach type
per runway codable
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
14
RNAV System Requirements
FMS limitations (4)
• Limited in procedure designation• 5 characters for waypoint names• 6 characters for airway designators• 6 characters for SID/STAR designators• Transition concept applied for SIDs/STARs
may not match with Source Documentation
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
15
RNAV System Requirements
AIRCRFAFT Owner• Aircraft owner responsible for:
• nav database contract• airline policy data• timely loading current data• assurance of integrity critical RNAV data
(requirement for RNAV)• pilot training/checking procedures for RNAV• communication via the database supplier
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
16
RNAV System Requirements
AIRCRAFT Manufacturer• Aircraft manufacturer
• End responsibility for ‘subcontractors’ (avionica manufacturers)
• Involvement in modification of software and hardware of any system in the aircraft
• Additional aircraft performance data added to the database disk
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
17
RNAV System Requirements
FMC Manufacturer• FMC manufacturer responsible for:
• data translation ARINC 424 into FMC language
• compatibility with all FMC’s (all update versions)
• Quality assurance process• FMC software updates
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
18
RNAV System Requirements
DATABASE Supplier• Database supplier responsible for:
• conversion source data into ARINC 424 ‘language’
• verification of coding• quality assurance (ED 76 compliant for
RNAV)• communication/verification with sources of
the data
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
19
RNAV System Requirements
Navigation Performance (1)
• RNAV performance aims are:1 Repeatability of the lateral path2 Flight path accuracy
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
20
RNAV System Requirements
Navigation Performance (2)
1 Repeatability of the Lateral Path• Safety aspect
• remain within the protected airspace• Obstacle clearance• Traffic separation
• Capacity aspect• ATC reaction to navigation ‘surprises’ : >>>> increase
of separation minima• Economical aspect
• Noise abatement
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
21
RNAV System Requirements
Navigation Performance (3)
2 Flight Path Accuracy• Significant increase in accuracy• Accuracy highly dependant on coding
applied• Significant freedom during turns
• May cause mitigating reaction by ATC• RF leg emerging
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
22
RNAV System RequirementsAccuracy, Integrity, Continuity & Availability
• General• History: ICAO RGCSP>>RNP Concept• Four parameters to control the safety of the
total system• Many changes in definition over the years• Now also used for sensor specific systems• Responsibility for adherence rests with the
user
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
23
RNAV System Requirements
ACCURACY (1)
• Accuracy The degree of conformance between the
estimated, measured, or desired position and/or the velocity of a platform at a given time, and its true position or velocity.
‘Where the system is’
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
24
RNAV System Requirements
ACCURACY (2)
• Position Update Components• DME old/new (provides radio update position)
and/or
• GPS/GLONASS (provides satellite update position) (Augmentation techniques emerging)
and additionally -if any-
• IRS(-es) (provides reference position), time related• ANP/EPU/EPE warning system (in case of RNP)
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
25
RNAV System Requirements
INTEGRITY (1)
• Integrity The ability of a system to provide timely
warnings to users when the system should not be used for navigation
‘Trusting the system that it is where it says it is’
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
26
RNAV System Requirements
INTEGRITY (2)
• Integrity level to prevent a catastrophic failure condition less than 1*10E-9 per flight hour (JAR 25-1309)
• Integrity trough (position) error detection and identification
• Contrary to accuracy, integrity is not measurable
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
27
RNAV System Requirements
INTEGRITY (3)• Difficult for complex systems• Even more difficult for highly software driven
systems • Integrity increased by multiple independent
system design and cross- checking between independent systems
• Independency through dissimilar design of multiple systems ?• E.g. independency of DME station selection
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
28
RNAV System Requirements
AVAILABILITY (1)
• Availability An indication of the ability of the system to
provide usable service within the specified coverage area
‘It’s there or it’s not there’
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
29
RNAV System Requirements
AVAILABILITY (2)
• Covers the risk of a lack of guidance at the start of the operation
• Risk mitigation through multi sensor design
• Provisions available to give timely alarm in case of loss of navigation
• Provisions to remain within a specified RNP level (RNP requirement only)
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
30
RNAV System Requirements
CONTINUITY of Function (1)
• Continuity of Function. The capability of the total system to perform
its function without non-scheduled interruptions during the intended operation
‘It will be there or it will not be there’
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
31
RNAV System Requirements
CONTINUITY of Function (2)
• The probability that the system will be available for the duration of a phase of operation (presuming that the system was available at the beginning of the operation)
• RAIM hole checks for the intended route• Continuity increased by multiple system
design (back-up)• Continuity controlled through multi-sensor
system design
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
32
RNAV System Requirements
WGS 84 (1)
• Need for accurate data in WGS 84• WGS 84 technically not required for ground
based updating systems, however…..• Implementation of WGS 84 is also a matter
of increased accuracy and quality control• Position determination of FMS without
GNSS sensor is relative to the ground station
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
33
RNAV System Requirements
WGS 84 (2)
• Problems may occur when station with a different reference datum is used
• Large deviations however should be filtered out by the FMC update algorithm
• Small differences could be accepted by the system>>Map shift
• GNSS sensored systems:• WGS 84 datum is absolutely a requirement
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
34
RNAV System Requirements
TOOLS (1)
• Need for appropriate tools• RNAV procedure design: coding
complexity decreased• Pressure for complexity in route design
(noise driven)• Noise abatement routes over-complex
compared to conventional design• Thorough testing required
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
35
RNAV System Requirements
TOOLS (2)
• Expert judgement for complex routes• Lap-top testing• Flight simulator check
• Maximum and minimum T/O weight• Maximum wind in strength and direction
• Actual flight trials via trial periods using designated operators
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
36
RNAV System Requirements
ADVISES In principle, adhere to the ‘minimum distance between way
points’ tables of PANS-OPS Cater for maximum assumed wind speed Cater for different wind directions Apply sufficient distance for first way point after DER Use TF coding as much as possible Apply Fly-over as alternative but... use DF after Fly-over coding, airspace permitting Cater for delayed turns Check flight paths with different FMCs Use S.I. PDT as initial check
RNAV in Europe - Procedure Design Master Class
EUROCONTROL
37
RNAV System Requirements