RNAV System Requirements · RNAV System Requirements EUROCONTROL FMS Architecture ... • Non...

1

RNAV in Europe - Procedure Design Master Class

EUROCONTROLRNAV 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

2


EUROCONTROLRNAV System Requirements (2)

• Navigation Performance• Accuracy, Integrity, Availability &

Continuity• Need for accurate data in WGS 84• Need for appropriate tools

3


EUROCONTROLRNAV 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

4



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

5



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

6




• 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

7




• 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

8




• At present, responsibility for coding rests with the database supplier

• Future: coding advise by the State Authority?

9



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

10



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

11



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

12



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

13



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

14



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

15



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

16



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

17



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

18



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

19



Navigation Performance (1)

• RNAV performance aims are:1 Repeatability of the lateral path2 Flight path accuracy

20




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

21




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

22


EUROCONTROLRNAV 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

23



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’

24



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)

25



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’

26



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

27



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

28



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’

29



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)

30



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’

31



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

32



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

33



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

34



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

35



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

36



ADVISESIn principle, adhere to the ‘minimum distance between way points’ tables of PANS-OPSCater for maximum assumed wind speedCater for different wind directionsApply sufficient distance for first way point after DERUse TF coding as much as possibleApply Fly-over as alternative but...use DF after Fly-over coding, airspace permitting Cater for delayed turnsCheck flight paths with different FMCsUse S.I. PDT as initial check

37



RNAV System Requirements · RNAV System Requirements EUROCONTROL FMS Architecture ... • Non...

Documents

Transcript of RNAV System Requirements · RNAV System Requirements EUROCONTROL FMS Architecture ... • Non...