Civil Aviation Advisory Publication System (GPS): general ... · PDF fileinstalled in the...

CAAP 35-1(0)

Global PositioningSystem (GPS):general installation guidelines

The relevant regulations• Civil Aviation Regulations (CAR) 21, 35, 42, 138 and

232A.

• Civil Aviation Orders (CAO) 20.18 para 9A, 100.37,100.6.4.1, 101.4.6.18.2, 108.20 and 108.34

• See other references page 18

Why this CAAP was written

This CAAP provides guidance on a range of matters thatneed to be considered to ensure that a GPS receiverinstalled in the aircraft is suitable for its purpose and isinstalled in accordance with the Design Standardsapplicable to the aircraft.

Status of this CAAP

This is the first CAAP to be written on GPS receiverinstallation and it supersedes AAC 6-26 Issue 3.

For further information

Contact the CASA Airworthiness District Office closest toyou.

Civil AviationAdvisory PublicationDecember 1997

This publication is onlyadvisory but it gives theCASA preferred method forcomplying with the CivilAviation Regulations.

It is not the only method,but experience has shownthat if you follow thismethod you will complywith the Civil AviationRegulations.

Always read this advice inconjunction with theappropriate regulations.

Contents…

Introduction 2

Approval Criteria 3

Requirementsapplicableto all installations 3

Specific InstallationRequirements:

VFR Supplemental 7

IFR Supplemental 8

IFR Primary-Domestic 11

IFR Primary-Oceanic 13

NPA Supplemental 14

Approval Procedures 17

Other references 18

Appendix 1 20

Appendix 2 23

Appendix 3 24

Appendix 4 25

2 CAAP 35-1(0): Global Positioning System (GPS):general installation guidelines

1. This CAAP describes an acceptable means, but not theonly means, of meeting the requirements of the DesignStandards applicable to the aircraft when dealing with adesign for the installation of GPS equipment intoAustralian registered aircraft. Alternative means ofcompliance need to be fully justified by the personsubmitting the design for approval. Persons choosing toadopt the means of compliance outlined herein areexpected to comply with all the requirements andunacceptable modification of any part of this CAAP wouldresult in a failure to obtain approval for the design.

2. A brief history of GPS and an explanation of terms isincluded at Appendix 1.

3. This CAAP also provides information and guidanceon the airworthiness requirements for GPS equipmentunder the provisions of CAR 21, CAR 42, CAR 138 andCAR 232A.

4. The topics covered are:

(a) the installation of GPS equipment as a non-approved Supplemental en-route aid tonavigation in aircraft operating under the VisualFlight Rules (VFR);

(b) the installation of GPS equipment as an approvedSupplemental en-route aid to navigation inaircraft operating under the Instrument FlightRules (IFR);

(c) the installation of GPS equipment as an approvedPrimary Means aid to navigation in IFRoperations including “GPS Arrivals”, “GPS/DMEArrivals”;

(d) the installation of GPS equipment as an approvedPrimary Means aid to navigation foroceanic/remote area operations;

(e) the installation of GPS equipment as an approvedSupplemental aid for Non-Precision Approaches(NPA), as published in the AustralianAeronautical Information Publication (AIP); and

(f) the requirement for, and preparation of, AircraftFlight Manual Supplements (AFM Supp).

Introduction

CAAP 35-1(0): Global Positioning System (GPS): 3general installation guidelines

5. Installation of GPS receivers into aircraft involveschanges to the aircraft configuration which can be achievedby either:

(a) an original modification design approved inaccordance with CAR 35;

(b) an applicable STC installed in accordance with theinstructions contained in the accompanying datapack. If insufficient information is available, orthe procedures detailed within the data pack arenot followed, or cannot be followed due to aprevious modification, then the installation is tobe approved in accordance with CAR 35; or

(c) the aircraft manufacturer’s Service Bulletin (SB).Any variation from the procedures or designdetailed in the SB is to be approved in accordancewith CAR 35.

6. CASA has determined that the Design Standards thatshould apply for GPS installations are those specified inFAR 23 Amdt 52, FAR 25 Amdt 91, FAR 27 Amdt 34, FAR29 Amdt 41. For operations under the IFR, GPS equipmentis required to have TSO C129/C129a or CASA approvedequivalent authorisation. Appendix 2 provides details ofthe classes of TSO C129/129a equipment.

APPROVALS REQUIRED

7. Appendix 3 details the approvals required for eachtype of installation.

8. The design of the installation is required to complywith those Design Standards that are applicable to theaircraft being modified. The general requirements listedbelow, as well as those listed for each different installation,provide guidance to assist the designer in maintainingthose standards. These are the minimum requirements tobe met for an installation to be accepted and the aircraftapproved for specific operations.

AIRCRAFT INSTALLATION

9. The need to minimise pilot workload and facilitateeasy access and operation of the controls during criticalphases of flight is essential. Adherence to establishedrules for the location of navigation displays and controlswill assist in achieving this goal.

Aircraft airworthinessstandards

Requirements applicableto all installations

4 CAAP 35-1(0) — Global Positioning System (GPS):general installation guidelines

Reference: FAR 23.1321/1381, 25.1321/1381, 27.1321/1381,29.1321/1381 and SFAR 23.12

10. The GPS equipment manufacturer’s data, in terms ofinstallation drawings and wiring diagrams, should be usedto ensure the correct installation of the system into aparticular aircraft. The holder of a CAR 35 Instrument ofAppointment (IoA) or delegation approving the design ofthe modification should take particular note of anymanufacturer’s installation limitations, such as antennapositioning, electrical system distribution and loading,structural requirements and cockpit layout. Justificationfor any deviations from the manufacturer’s limitationsmay need to be provided for assessment by CASA. Priorto final approval the holder of a CAR 35 IoA or delegationis to ensure that the equipment, after installation, functionsproperly.

Reference: FAR 23.1301, 25.1301, 27.1301 and 29.1301.

11. Guidance on acceptable radio equipment installations,covering both mechanical and electrical aspects, can befound in FAA AC 43.13-2A.

12. The installation in an Australian registered aircraft isto be performed in accordance with CAR 42ZC withinAustralia and CAR 42ZD outside Australia.

GPS FAILURE INDICATION

13. A clearly visible and unambiguous failure indication isto be provided to indicate to the flight crew when the GPSequipment has failed or is unable to perform positioncalculations. The failure/status indications provided byapproved GPS equipment as part of the normal displaysatisfy this requirement if that display is clearly visible tothe pilot.

14. All instruments providing a display of GPS derivedinformation must have a means of indicating the failure ofthat source of information, e.g. an “off flag”.

Note: Presentation of a failure/status annunciation does notrequire removal of navigation information from thenavigation display.

Reference: FAR 23.1309/1321/1322, FAR 25.1309/1321/1322, FAR 27.1321/1322 or FAR 29.1309/1321/1322refer. AC 23-1309-1A provides additional information.


NAVIGATION SOURCE ANNUNCIATOR

15. If the GPS equipment installation supplies anyinformation to a display such as a Horizontal SituationIndicator (HSI), Course Deviation Indicator (CDI), distancedisplay, electronic map, etc., then a navigation sourceannunciator, clearly identifying the source of theinformation currently displayed, is to be provided in clearview of the pilot. Switch position is not a sufficientindication of information source.

Note: This requirement originates from the need to ensure thathazardously misleading information is not presented tothe pilot. A visual cue is required to confirm the sourceof the navigational information being displayed.

Reference: FAR 23.1309, 25.1309, 27.1309 or 29.1309; sub-section b.3.

AUTOPILOT/FLIGHT DIRECTOR COUPLING

16. Only permanent GPS equipment installations are to becoupled to an autopilot and/or flight director. Hand heldunits carried on or mounted in adapter cradles/mounts inthe aircraft are not be used in this configuration. Theaircraft is to be flight tested to ensure that the GPSreceiver/autopilot coupling functions as intended. Ifmultiple steering input sources are available to anautopilot, clear and unambiguous visual indications are tobe given to positively identify the current source of input.

Reference: FAR 23.1329, 25.1329, 27.1329 or 29.1329;subsection h.

GPS EQUIPMENT MAINTENANCE

17. As part of the design package, the holder of a CAR 35IoA, or delegation, is to specify the maintenancerequirements for the installation, e.g. periodic maintenancefor installed internal batteries, for inclusion into the aircraftsystem of maintenance or a log book statement. Thisshould be in compliance with manufacturer’srecommendations and any variation may need to bejustified.

NAVIGATIONAL DATA BASE MAINTENANCE

18. It is the pilot’s responsibility to ensure that thedatabase to be used for the particular phase of flight iscurrent. The updating of the database is a maintenance


function and may require the authorisation of the person,other than a LAME, performing the update. Additionalinformation regarding obtaining a maintenance authoritycan be obtained from the local CASA office.

AIRCRAFT FLIGHT MANUAL SUPPLEMENT (AFM SUPP)

19. An appropriate AFM Supp, containing the limitationsand reference to the manufacturer’s operating proceduresapplicable to the equipment installed, should be submittedto CASA or Authorised Person for approval under CAR138.

20. GPS equipment fitted only for VFR Supplemental en-route navigation does not require a AFM Supp.

21. The layout for a AFM Supp should follow the formatfor the approved flight manual and include the following:

(a) General. This section is to contain a brief generaldescription of the particular GPS equipmentinstallation, e.g. receiver type, details of remoteannunciator etc.

Note: Full details of the system installed in the aircraft,including reference to the CAR 35 approvaldocumentation controlling the incorporation, arecontained in the aircraft log book.

(b) Limitations. Any limitations on the use of thesystem, e.g. in the integrated mode, are to bespecified.

(c) Emergency/Abnormal Procedures. Proceduresdetailed in the manufacturer’s handbook wouldbe sufficient (if applicable).

(d) Normal Procedures. This section contains eitheroperating procedures in terms of manufacturersinstructions or reference to the manufacturesoperating manual, which would then be requiredto be available to the aircrew at all times whilst inflight. Instructions detailing the method ofoperation of the integrated system in the coupledmode is to be included. Details are to be providedexplaining all the functions and indicationsprovided by the remote annunciators, switchesand placards etc.

(e) System Description. Details of the integration ofthe GPS equipment into the aircraft system/s areto be provided in this section.


Reference: FAR 23.1581-1585, 25.1581-1585, 27.1581-1585 or29.1581-1585.

EQUIPMENT STANDARD

22. GPS equipment is not yet an approved aid tonavigation for use under the VFR and can only be used asa supplemental navigation system.

Note 1: Whilst there are no equipment standards for VFRSupplemental GPS, the output from this type ofequipment may be used to provide azimuth informationfor the autopilot however the receiver must bepermanently mounted

Reference: FAR 23.1329, 25.1329, 27.1329 or 29.1329.

Note 2: The equipment display should be illuminated to ensurereadability during night operations

Reference: FAR 23.1381, 25.1381, 27.1381 or 29.1381.

SYSTEM COMPATIBILITY

23. The holder of a CAR 35 IoA, or delegation, whenapproving the design of GPS equipment installations foroperations limited to VFR, is to ensure that the design doesnot constitute a hazard to the aircraft or crew.

Reference: FAR 23.1351/1431, 25.1353/1431, 27.1351 or29.1353/1431.

VFR LIMITATION PLACARD

24. If GPS equipment that does not have TSO C129/C129aor equivalent authorisation a placard stating that:“The GPS equipment fitted is not an approved aid tonavigation”is to be installed in clear view of, and easily readable, bythe pilot.

Note: GPS has not been approved as an aid to navigationunder the VFR as a result of concerns over the followingissues:

(a) there are no design standards apart from the TSOC129/129a,

(b) selected equipment may not be appropriate for thetask,

(c) no required purpose under the VFR, and

(d) without a approved RAIM facility the navigationaldata produced by the system cannot be guaranteed

VFR supplementalnavigation system —domestic enroute


because the satellite availability and accuracy aresubject to change.

Reference: FAR 23.1541, 25.1541, 27.1541 or 29.1451.

EQUIPMENT STANDARD

25. GPS navigation equipment, to be approved as aSupplemental Navigation System for oceanic en-route anddomestic en-route operations must have a TSO-C129 orC129a or CASA approved equivalent authorisation.

SYSTEM INSTALLATION

26. The holder of a CAR 35 IoA, or delegation, whenapproving the design of GPS equipment installations forIFR en-route supplemental navigation, is to ensure that thedesign complies with the minimum requirements listed inthe general requirements section of this CAAP (paragraph9 to 21 inclusive), together with those detailed herein.


27. The GPS equipment installation must not be a sourceof electromagnetic interference, nor be adversely affectedby electromagnetic interference from other equipment inthe aircraft.

28. The interfaces with other aircraft equipment are to bedesigned such that normal or abnormal use of the installedGPS equipment does not adversely affect the operation ofother equipment, nor will normal or abnormal operation ofother equipment adversely affect the GPS equipmentoperation.

29. The system compatibility, as described, should beconfirmed by functional testing in accordance with thisCAAP (paragraph 31) and the references below.

Reference: FARs 23. 1309/1431, 25. 1309/1431, 27. 1309/1431 or 29.1309/1431 refer. Additional information ontesting methodology can be found in AC 23-1309-1A.

TEST AND EVALUATION OF INSTALLATION

30. As part of the design approval, the holder of a CAR 35IoA, or delegation, is to determine the extent of testing thatis to be conducted for every installation to verify that theinstalled GPS equipment operates correctly. To confirm

IFR supplementalnavigation system


correct operation of the installation the following tests, as aminimum, are suggested:

(a) ensure all operating modes of the GPS equipmentoperate in accordance with the approved design;

(b) ensure the coupled function of other equipmentconnected to the GPS equipment operates inaccordance with the approved design;

(c) ensure the various failure modes and associatedannunciations (such as loss of electrical power,loss of signal reception and GPS equipment failureetc.) operate in accordance with the approveddesign;

(d) ensure the displayed GPS derived navigationparameters on coupled cockpit instruments (ifconnected) such as the HSI, CDI, distance display,Electronic Flight Instruments System (EFIS),moving maps and fuel management systems,correctly duplicate the display on the GPS receiverdisplay;

(e) ensure all switching and transfer functions,including electrical bus switching, pertaining tothe GPS equipment installation function asintended in the approved design.

(f) demonstrate satisfactory electromagneticcompatibility requirements between the GPSequipment installation and other onboardequipment. Some installations may exhibitsignificant EMI/EMC problems brought about bythe age and brand of electronic equipment fittedto the aircraft or by the lack of room needed tomount the GPS antenna in an optimum position.Testing for harmonic interference is to beperformed to determine the effectiveness of thedesign. Filtering of the outputs ofcommunications transmitters, as an example, maybe required to obtain a satisfactory level ofperformance.

Note 1: The GPS signal is typically below the value of thebackground noise. Electrical noise in the vicinity of theantenna can adversely affect the performance of thesystem. Antenna installation in close proximity to TrafficAlert and Collision Avoidance System (TCAS), satellitecommunication (SATCOM), DME and other transmittingantennas (particularly ‘L’ band) are to be carefullyevaluated for potential mutual interference.


Intermodulation effects are possible between multiplechannel SATCOM installations and GPS receivers.

Note 2: Harmonic interference from VHF transmissions on, butnot limited to, 121.150, 121.175, 121.200, 131.250,131.275 and 131.300 MHz may adversely affectreception of the GPS signal if sufficient attenuation ofharmonics is not provided.

Note 3: A minimum separation of 1.1 meters centre to centrebetween a GPS antenna and any ‘L’ band transmittingantenna is essential to minimise interference. Similardistances should be maintained to all other transmittingantennae.

(g) ensure all GPS receiver controls are suitablylocated so as to be readily accessible and useableby the pilot and co-pilot (if required) from theirnormal seated position in the aircraft’s normalcruise configuration.

(h) ensure all controls, displays and annunciationsrelating to the GPS equipment are clearly visibleduring day and night lighting conditions.

(i) to demonstrate that the GPS navigationalperformance has not been adversely affected bythe installation in the aircraft and to confirm theoperation of the GPS equipment integration intoany aircraft system the holder of CAR 35 IoA, ordelegation, is to determine the need for, and theextent of, flight testing. The purpose of flighttesting is to:

(i) ensure that continuity of navigation data ismaintained by ensuring that all satellitesabove the mask angle are receivable in anyattitude or direction that can be sustained. Ifnecessary, the extent of any bad receptionareas need to be identified. A suggested flighttest evaluation sheet is attached atAppendix 4.

(ii) validate the integration to the autopilot/flightdirector to ensure the system operatescorrectly in all phases of flight.

(iii) determine the suitability of the installedsystem with regards to human factorsconsiderations.


NAVIGATION DATA BASE

31. Systems used for en-route supplemental navigation donot require the incorporation of a navigation data base,however, if the facility is fitted the data used is to comefrom a validated navigation data base supplied by anapproved source in accordance with the informationcontained in the Australian AIP.

OTHER NAVIGATION EQUIPMENT REQUIRED

32. An aircraft employing GPS equipment forsupplemental IFR navigation is to be equipped with a SoleMeans navigation system.


33. In addition to the general requirements, the followingare required for IFR Supplemental installations:

Limitations. All limitations should be stated in theappropriate section. The following limitations areconsidered the minimum acceptable:

(a) The GPS equipment fitted is not approved aseither a primary means or sole means ofnavigation.

(b) Users are cautioned that satellite availability andaccuracy are subject to change.

(c) The pilot is to monitor approved NAVAIDS andutilise GPS derived position information assupplemental only.

EQUIPMENT STANDARD

34. GPS navigation equipment, to be approved as aPrimary Means Navigation System is to, in addition tohaving a TSO-C129 or C129a authorisation, or CASAapproved equivalent, also have pressure altitude data(barometric aiding) automatically provided to the receiverfrom an approved source, e.g. an encoding altimeter.

SYSTEM INSTALLATION

35. The holder of a CAR 35 IoA, or delegation, whenapproving the design of GPS equipment installations forIFR Primary Means navigation, is to ensure that the designcomplies with the minimum requirements listed below.

IFR primary meansnavigation system —domestic enroute


Any deficiencies highlighted during testing are to beremedied prior to final approval.


36. The system compatibility requirements are the sameas detailed for IFR Supplemental Means, paragraphs 27 to29.

37. In an integrated system that has the capacity todisplay either GPS or ILS derived azimuth information ona CDI/HSI, an automatic capability may be used to ensurethat when GPS information is being displayed and an ILSfrequency is selected on the primary VHF navigationreceiver (Nav1), the azimuth information being displayedon the CDI/HSI reverts from GPS to ILS inputautomatically. This system is acceptable provided that thenavigation source indicator clearly and accuratelyidentifies the source change.

Note: Installations that utilise an illuminated switch for theselection of navigation sources may not be acceptable.

TEST AND EVALUATION OF INSTALLATION

38. The suggested test and evaluation is the same as forIFR Supplemental Means, paragraph 30.

BAROMETRIC ALTITUDE DATA (BARO-AIDING)

39. The provision of pressure altitude data from anapproved source (i.e. barometric aiding) is a mandatorycomponent of the GPS system required for approval of theinstallation for IFR Primary Means navigation as detailedin the Australian AIP. The holder of the CAR 35 IoA, ordelegation, is to ensure that:

(a) any interface used to convert altitude data fromone format to another does so in a manner thatdoes not corrupt or alter the integrity of that data;and

(b) the altitude encoding device has TSO C88a orequivalent authorisation.

40. The provision of altitude data to the GPS receivershould not to be dependent on other, unrelated systems.

Note: In some installations, altitude data is sourced from atransponder dependent blind encoder via a dataserialiser. The transponder itself provides the additional


circuitry necessary for the data transfer. In this type ofinstallation, when the transponder is not powered,altitude data is not available to the GPS and the GPSsystem does not meet the requirements of IFR PrimaryMeans navigation. Duplication of the altitude encoder isnot required, however, additional circuit design would berequired to overcome this deficiency.


41. The data used for navigation is to come from avalidated navigation data base supplied by an approvedsource in accordance with the information contained in theAustralian AIP.

OTHER NAVIGATION EQUIPMENT REQUIRED

42. An aircraft employing a GPS receiver for IFR PrimaryMeans navigation is to be equipped with a Sole Meansnavigation system.


43. In addition to the general requirements, the followingis to be included for IFR Primary Means installations:

The following wording or similar should be included in thegeneral section:

This system may be used as a Primary Means of IFRnavigation for en-route and terminal operationsincluding GPS arrivals, GPS/ DME arrivals.

Limitations. All limitations should be stated in theappropriate section. The following limitations are theminimum considered acceptable:

(a) The GPS equipment fitted is not approved as asole means of navigation.

(b) The pilot is to monitor approved NAVAIDS andcompare the information with GPS derivedposition information.

(c) Operation without RAIM is abnormal and thenavigation information provided should not berelied on.

44. Refer to CAAP 35-2 Issue 0 (Currently underdevelopment, however, in the interim FAA Document8110.60 provides guidance for approval.)

IFR primary meansnavigation system —oceanic/remote areaenroute


MINIMUM REQUIREMENTS FOR NPA INSTALLATIONS

45. GPS navigation equipment, to be approved as aSupplementary Means Navigation System for NPAs:

(a) must have TSO-C129 or C129a, Class A1, B1, B3,C1 and C3 only, or CASA approved equivalentauthorisation;

(b) be capable of approval for IFR Primary MeansNavigation System, Domestic En-route, asdetailed in this CAAP; and

(c) comply with the minimum requirements of thissection or an alternate, equivalent level of safety.

RECEIVER/CONTROL PANEL PLACEMENT

46. To safely execute a GPS non precision approach a pilotmust have essential navigation information includingazimuth indication, waypoint information and GPSreceiver message functions presented in a clear and legibleformat. Ready access to the GPS receiver during theapproach is required by the pilot or, in the case of two pilotoperations, the non flying pilot to enable the receiver to beoperated correctly.

47. An integrated system that has an automatic capacityto switch displays between either GPS or ILS derivedazimuth information on a CDI/HSI should not be used.

Note: Having this facility would prevent a pilot from conductinga NPA and having an ILS frequency selected, as analternative, at the same time.

48. The following paragraphs provide guidance onequipment location and access for the common operationalconfigurations.

Reference: FAR 23.1321/1322, 25.1321/1322, 27.1321/1322or 29.1321/1322.

SINGLE PILOT OPERATION

49. For single pilot operations the azimuth, waypoint andmessage information may be provided by a displaycontained within the receiver. The GPS annunciator panel,which displays MSG, WPT, HOLD and APP lights, is to bein the pilot’s primary field of view.

IFR supplementarymeans navigationsystem for non-precision approaches


50. Receiver Only: The receiver/control panel display isto be mounted in such a position as to:

(a) provide the pilot clear and unobstructed view ofthe data screen allowing the pilot to see thedisplay enabling the extraction of essentialnavigational information including azimuthindication, waypoint information etc.;

(b) be viewable from the pilot’s normal seatedposition and be within the primary scan area; and

(c) ensure all controls that are normally adjusted inflight are readily accessible.

Note: For single pilot operations without integrated electronicdisplays, the placement of the GPS receiver in thecentral pedestal is not acceptable.

51. Receiver with remote CDI/HSI display: If fitted, theremote display is to be mounted on the instrument panelwithin the pilot’s primary field of view. This may beprovided by a dedicated CDI/HSI type instrument or as aswitched input to a multiple display. The GPS annunciatorpanel, which displays MSG, WPT, HOLD and APP lights,is to be on the primary instrument panel. Thereceiver/control panel display is to be mounted in such aposition as to:

(a) provide the pilot clear and unobstructed view ofthe data screen allowing the pilot to see thedisplay enabling the extraction of essentialnavigational information including azimuthindication, waypoint information etc.;

(b) be viewable from the pilot’s normal seatedposition and be within the primary scan area; and

(c) ensure all controls that are normally adjusted inflight are readily accessible.

Note: For single pilot operations without integrated electronicdisplays, the placement of the GPS receiver in thecentral pedestal is not acceptable as it does not allowthe pilot a clear and unobstructed view of the datawindow.

TWO PILOT OPERATIONS

52. For aircraft operations that require two pilots, thedisplay of GPS derived navigation information is to beduplicated to the extent necessary to enable either pilot,when in control of the aircraft, to view the azimuthnavigational information within their primary viewing


area. Receiver/control panel placement is to be central andaccessible to either pilot to enable the non-flying pilot toeffectively operate the equipment and utilise the receiverdisplay, where necessary, to perform the cross checkingfunction. The GPS annunciator panel, which displaysMSG, WPT, HOLD and APP lights, must be located suchas to be either clearly visible to both pilots or duplicated onthe respective instrument panels.

Note: In some installations it may not be feasible to provideduplicate displays of GPS derived information.Operators utilising installations where the navigationdisplays between the flying pilot and non-flying pilotdiffer should provide adequate description of the methodof operation in the AFM Supp, Operations Manual and inthe flight crew checklist (as appropriate).

SINGLE/DUAL PILOT OPERATIONS WITH INTEGRATED

ELECTRONIC DISPLAYS

53. Where an aircraft is fitted with electronicmultifunction displays that form part of a FlightManagement System (FMS) and the GPS is integrated intothat FMS, the GPS control panel is to be placed in aposition that ensures all controls that are normallyadjusted in flight are readily accessible

Reference: FAR 23.1311, 25.1311, 27.1311 or 29.1311.

POWER SUPPLY

54. Consideration should be given by the designer of theinstallation modification to provide aircraft power to theGPS equipment from an essential bus (if the aircraft isequipped with such). If this design approach is taken anelectrical load analysis must be conducted to ensure theminimum requirements for battery power reserve are metgiven the additional load imposed by the GPS receiver.

Reference: FAR 23.1353, 25.1353, 27.1353 and 29.1353.

AUDIO OUTPUT

55. To assist in situational awareness and provide anadded alert facility the audio output from the GPS receivershould be connected to the aircraft audio system in amanner that allows pilot selection of tone and volume.


TEST AND EVALUATION OF NPA INSTALLATION

56. As part of the design approval the holder of the CAR35 IoA, or delegation, is to determine the extent of testingthat is to be conducted for every installation to verify thatthe installed GPS equipment, intended for NPAs, can beoperated in accordance with the approved design.


57. The data used for NPAs shall come from a validatednavigation data base, supplied by an approved source inaccordance, with the current Australian AIP information.


58. In addition to the information detailed for IFR PrimaryMeans Navigation System, Domestic En-route AFM Supp,the following should be included for Supplementary NPAinstallations:

General Section: The following wording or similar shouldbe added in the general section:

This system may be used for approved SupplementalNon-Precision Approaches as published in the AIP.

Limitations: The following is acceptable:

NPA procedures are not to be conducted withoutRAIM.

59. All installations of GPS equipment into aircraft areaircraft modifications. The person having an IoA orDelegation under CAR 35, when approving themodification, shall ensure that the design satisfies thedesign standards specified.

60. GPS equipment intended for VFR Supplemental useonly does not require TSO-C129/C129a or equivalentauthorisation and as such is not an approved aid tonavigation.

61. GPS equipment approved for Supplemental Meansunder IFR use is to have either TSO-C129 or C129a orCASA approved equivalent authorisation.

62. GPS equipment approved for Primary Means underIFR use shall have TSO-C129 or C129a or CASA approvedequivalent authorisation together with automatic

Summary of approvalprocedures


barometric aiding from an approved source. Thereceiver/control panel is to be installed in clear view of thepilot and capable of unobstructed operation from thepilot’s normal seated position.

63. GPS equipment approved for Supplementary MeansNPA use shall have TSO-C129/129a or CASA approvedequivalent authorisation and automatic barometric aidingfrom an approved source. The receiver/control panellocation, together with any additional displays will bedetermined according to the crew requirements of theaircraft and the existing avionics suite.

64. Where a AFM Supp is required, the proposed AFMSupp should form part of the design package

65. The need for flight testing is to be determined by theCAR 35 IoA holder or delegate.

• RTCA Inc Document DO-208

• ICAO Circular 267-AN/159 Guidelines for theInstallation and Operational Use of the GlobalNavigation Satellite System (GNSS)

• Federal Aviation Administration (FAA) TechnicalStandard Order (TSO) C129/129a AirborneSupplemental Navigation Equipment Using The GlobalPositioning System (GPS)

• FAA TSO C88a Automatic Pressure Altitude ReportingCode Generating Equipment

• FAA Regulation (FAR) Parts 23, 25, 27 or 29 Sections:773, 1301, 1309, 1321, 1322, 1329, 1335, 1351, 1381, 1431,1541 and 1581-1585

• FAA Advisory Circular (AC) 20-69 Conspicuity ofAircraft Instrument Malfunction Indicators

• FAA AC 20-138 Airworthiness Approval of GlobalPositioning System (GPS) Navigational Equipment forUse as a VFR and IFR Supplemental NavigationalSystem

• FAA AC 23-1309-1B Equipment, Systems andInstallations in FAR 23 Aircraft

• FAA AC 25-10 Guidance for Installation ofMiscellaneous Nonrequired Electrical Equipment

• FAA AC 25-1309-1A System Design Analysis

• FAA AC 27-1 Certification of Normal CategoryRotorcraft

Other references


• FAA AC 29-2A Certification of Transport CategoryRotorcraft

• FAA AC 43-13-2A Acceptable Methods, Techniquesand Practices Aircraft Alterations

• FAA Notice 8110.60 GPS as a Primary Means ofNavigation for Oceanic/Remote Operations

• Who this CAAP applies to

• Persons approving the design of aircraft modificationsinvolving the installation of TSO C129/129a or otherCASA approved GPS receivers.

• Persons or organisations holding acceptedSupplementary Type Certificates (STC) dealing withthe installation of GPS equipment.

• Certificate of Registration (CoR) holders of aircrafthaving GPS receivers fitted.

20 CAAP 35-1(0): Global Positioning System (GPS):general installation guidelines

APPENDIX 1SYSTEM DESCRIPTION.

The GPS is a United States Government system operated by the Department of Defense(DoD). It consists of a twenty four orbiting satellite constellation. The system provides anaid to radio navigation which uses precise range measurements from the GPS satellites toenable accurate position fixes to be determined anywhere in the world. The satellites’measured orbital parameters (ephemeris data) are combined with precision onboard timingsignals and broadcast as a composite signal. The receiver processes this information todetermine its position in space.

GPS position information is expressed in the Cartesian, earth-centred, earth-fixed co-ordinates as specified in the World Geodetic System 1984 (WGS-84). Whilst there are othersystems available, WGS-84 is the only system authorised for use in Australian airspace.Navigation values, such as distance and bearing to a waypoint, ground speed, etc., arecomputed from the aircraft’s latitude/longitude and the location of the waypoint. Courseguidance is usually provided as a deviation from the desired track of a Great Circle coursebetween defined waypoints.

The United States DoD declared GPS had full operational capability (FOC) in April 1995.However, even after FOC, GPS by itself, does not meet all the integrity, accuracy, continuityof service and availability requirements needed for sole means IFR operations.

Terminology

Integrity. GPS signal integrity relates to the trust which can be placed in the correctness ofthe information supplied by the total system. This includes the ability of the system tonotify the pilot if a satellite is radiating erroneous signals.

Receiver Autonomous Integrity Monitoring (RAIM). A technique whereby a civil GPSreceiver/processor determines the integrity of the GPS navigation signals using only GPSsignals or GPS signals augmented by altitude information. This determination is achievedby a consistency check among redundant pseudorange measurements. At least one othersatellite, in addition to those required for navigation, is required.

A further enhancement to this technique is Fault Detection and Exclusion (FDE). Thisenables the receiver to identify which satellite is in error and to exclude it from thenavigation solution. This capability requires an additional satellite bringing the minimumnumber to six.

For the particular phase of flight being undertaken, i.e. en-route, approach etc., there is anallowable positional tolerance. When the calculated positions from the variouscombinations of satellites are compared the differences between each calculated positionshould not exceed that tolerance. If this tolerance is exceeded a ‘RAIM Warning’ indicationis given by the receiver. Situations may arise when the receiver will indicate that RAIM hasbeen lost (display of this message is receiver dependent). This occurs when not enoughsatellites are in view, or the geometry of the satellites is poor.

The incorporation of barometric altitude data into the system, from an approved source,provides a simulated GPS satellite for the receiver to compare to the available satellites. Thishas the benefit of reducing the minimum satellite count to four (or five if FDE is included).


Receivers that have TSO C129/129a authorisation or CASA approved equivalent haveRAIM or an equivalent integrity monitoring system. For non TSO compliant receivers,rudimentary GPS integrity checking can be achieved by comparing the navigationalinformation provided with monitored traditional NAVAIDS such as VOR or NDB.

Availability. The percentage of time that the services of the system are useable and is anindication of the ability of the system to provide useable service within the specifiedcoverage area. It is a function of both the physical characteristics of the environment andthe technical capabilities of the transmitter facilities.

GPS availability is the system’s capacity to provide the number of satellites required forposition fixing. A minimum of three satellites need to be in view to determine a twodimensional position, whilst four are required to establish an accurate three dimensionalposition.

System Accuracy. Each satellite transmits a unique code string containing a precise timesignal together with the satellite identifier. The distance from that satellite to the GPSreceiver is calculated by utilising this precise time signal. The receiver computes its positionby combining the distances from selected satellites in the constellation and the satellites’known locations. The accuracy of GPS derived position data can be affected by equipmentcharacteristics and various geometric and atmospheric factors. Many of these errors arecompensated by mathematical algorithms built into the receiver, however some cannot becorrected due to their variable nature, e.g. ionospheric effects.

Selective Availability (SA) is a technique used by the US DoD for denying the full accuracyof the system to other than approved (military) users. SA is achieved by artificially creatinga significant clock and/or ephemeris error in the satellite.

GPS derived position accuracy is currently stated to be 100m or less, 95% of the time, and300m or less, 99.9% of the time. The US DoD has guaranteed a maximum error of 500m.

Continuity of Service. Continuity of service is the ability of the total system to continue toperform its function during the intended operation. Although the GPS satellite system hasbeen declared FOC with 24 satellites in orbit, the possibility exists that breakdowns willoccur. It has been estimated that at least 21 satellites will be operational 98% of the time.With less than 24 satellites operating, GPS navigation capability may not be available atparticular locations at certain times. The US DoD has guaranteed 24 satellites will beavailable 70% of the time.

Equipment Classes. GPS equipment which holds TSO authorisation is identified byequipment class. There are three main classes of GPS equipment which are further dividedto form 10 sub-classes. Class A relates to stand-alone GPS equipment, while Classes B andC relate to GPS equipment as part of a multi-sensor navigation system. Appendix 2provides a summary of the 10 sub-classes. For a more detailed explanation of the variousclasses, refer to TSO-C129 or C129a.

Sole Means Navigation System. A navigation system that, for a given phase of flight,allows the aircraft to meet all four navigation system performance requirements - accuracy,integrity, availability and continuity of service.

Note: This definition does not exclude the carriage of other navigation systems. Any sole meansnavigation system could include one (stand alone installation) or several sensors possibly of differenttypes (multi-sensor installation).

22 CAAP 35-1(0) — Global Positioning System:general installation guidelines

Primary Means Navigation System. A navigation system that, for a given operation orphase of flight, meets accuracy and integrity requirements, but need not meet fullavailability and continuity of service requirements. Safety is achieved by either limitingflights to specific time periods, or through appropriate procedural restrictions andoperational requirements.

Note: This is particularly significant because the GPS provides wide area coverage, whereas otherapproved navigation aids such as VOR/DME offer distributed system redundancy. For example, aGPS measurement signal failure reduces or eliminates the GPS navigation capability over a wide areawhereas, a single VOR/DME failure affects only a small area.

Supplemental Navigation System. A navigation system that is used in conjunction with asole means navigation system. Approval for supplemental means for a given phase of flightrequires that a sole means navigation system, for that phase of flight, is on board and ismonitored and cross checked. Amongst the navigation system performance requirementsfor a given operation or phase of flight, a supplemental means navigation system is to meetthe accuracy and integrity requirements for that operation or phase of flight; there is norequirement to meet availability and continuity requirements.

Hand Held Equipment. Equipment that is portable and operates off an internal battery andan integrated (internal or external) antenna. There may be provision for a remote antennathat is temporarily attached to the aircraft using suction cups, clamps etc. No modificationis made to the aircraft structure or electrical wiring. Since hand held GPS receivers, at thistime, do not provide a RAIM type function for integrity checking they are not an approvedaid to navigation and their use is limited to VFR supplemental en-route. If a hand held unitis to be used for VFR Supplemental navigation, CASA strongly recommends that a typeidentified by the manufacturer as being suitable for aviation purposes is used.

Note: Hand held units not identified as suitable for aviation purposes generally areunable to calculate position when the receiver is travelling at aircraft speed.

Non Integrated Equipment. Equipment that is either:

(a) permanently mounted into the aircraft, supplied with aircraft power andconnected to an external antenna, or

(b) a portable unit that is fitted to a dedicated cradle which is permanentlymounted in the aircraft, designed to be provided with aircraft power and, ifrequired, connection to an external antenna.

These units do not provide data to, nor do they receive data from, any aircraft system.

Note: the term ‘non integrated’ is used in preference to the term ‘stand alone’ as that term has adifferent meaning within the TSO-C129 or C129a.

Integrated Equipment. Equipment that is permanently fitted to the aircraft, suppliedaircraft power and is connected to an external antenna. The unit provides input to otheraircraft systems and/or receives input from other aircraft systems.

Multi sensor systems where GPS is one of many inputs to a flight management system arethe subject of a separate CAAP.


APPENDIX 2

TECHNICAL STANDARD ORDER (TSO) C129 - EQUIPMENT CLASSES

Equipment Characteristics Equipment Capability

Class StandAlone

Multi-Sensor

AutoPilotReq

RAIM RAIMEquip

En-route

Terminal NonPrecisionApproach

A1 X X X X X

A2 X X X X

B1 X X X X X

B2 X X X X

B3 X X X X X

B4 X X X X

C1 X X X X X X

C2 X X X X X

C3 X X X X X

C4 X X X X


APPENDIX 3

APPROVALS REQUIRED

CAR 35 (2) CAR 138 (3)

Hand Held No No

VFRNonIntegrated(Non TSO)

Yes No(1)

Integrated(Non TSO)

Yes No(1)

IFR

NonIntegrated(TSO)

Yes Yes

Integrated(TSO)

Yes Yes

Note 1: A placard is required on or adjacent to the display unit to clearly show its limitation to VFRand reference to vendor manual is suggested.

Note 2: Log book compliance with CAR 42U should not be completed until all designdocumentation is available and CAR 35 approval issued.

Note 3: The AFM Supp must contain reference to the CAR 35 approved document upon which thedesign/operating limitations and conditions are based. A draft AFM Supp may be submitted forconsideration under CAR 138 (1)(a) in anticipation of compliance with CAR 42U. However, thedesign document and AFM Sup must align in their final form to allow CAR 138 approval and issueof the Supp to the aircraft; any associated Operation Manual amendment should occur at the sametime, para 9A of CAO 20.18 refers.


APPENDIX 4

FLIGHT TEST EVALUATION SHEET

AIRCRAFT TYPE: ……………. Model ……………… Registration VH-……

GPS SYSTEM: Type…………….. Model……………… S/N………………..

1.0 INTRODUCTION:

1.1 This document describes the flight test procedure designed to test the functions andserviceability of the GPS installed in the aircraft

1.2 The checklist is required to be finalised by an appropriately rated LAME andcertified in the certification box at the bottom of the document.

1.3 Approved data package used in this installation: …………………………………..

2.0 INSTALLATION EVALUATION:

TEST INSTRUCTIONS PASS FAIL

2.1 Verify that the NAV data base as shown in the initialisation page iscurrent

2.2 Verify that after switch on the correct software version is displayed onthe relevant data page. Record software version: ………….

2.3 Verify that all annunciators introduced by this installation operatecorrectly during self-test and dim checks.

2.4 Verify that all switching functions operate correctly, both on the GPSsystem and external.

2.5 Perform any other test deemed necessary, and record test:-

PAGE 1 OF 3


3.0 PREFLIGHT GROUND TESTS


3.1 Create a flight plan appropriate to the flight test to be performed andverify proper operation in accordance with the Operator’s Manual.

3.2 Verify correct input of all data:- Air Data (TAS ………..ALT ………)GPS; ……….. HDG; …………. FF; ………. By checking theappropriate data pages.

3.3 With GPS displayed on each relevant display, verify proper display ofdeviations, To/From flags, bearing to waypoint, desired track anddistance to waypoint.

3.4 Verify that all switching functions operate correctly, both on the GPSsystem and external.


4.0 FUEL DATA EVALUATION (AS REQUIRED)


4.1 Enter the known fuel state of the aircraft on the appropriate data pageincluding weight data if applicable.

4.2 Select the appropriate fuel page and check the fuel flow forreasonableness with the aircraft’s fuel flow indicators. Verify the flowdata is reasonable for low, medium and high power settings, on theground and in flight.


PAGE 2 OF 3


5.0 FLIGHT EVALUATIONTEST INSTRUCTIONS PASS FAIL5.1 Evaluate the accuracy of the GPS by recording latitude, and longitude

of geographic points such as VORs, DMEs, or runway touch downpoints or thresholds, on a flight of at least 1 hour. Data should betaken ( minimum of 5 readings ) during overflight or at touchdown.The accuracy of the GPS should be better than 1NM.

5.2 Evaluate the GPS data pages and ensure the navigation datapresented corresponds to that displayed on the flight instruments.

5.3 Evaluate the steering response (roll steering) of the GPS whencoupled to the autopilot/flight director. Verify that leg changes donot result in unacceptable over or undershoot conditions.

5.4 Evaluate the cross track or offset tracking performance. Verify that theoffset appears reasonable and meets stated accuracy

5.5 De select satellites and confirm appropriate annunciation Verify allappropriate warning flags appear on the flight instruments. Reselectsatellites and verify the warning and flag conditions clear.

5.6 Fail the GPS system circuit breakers and verify the flight instrumentNAV flags come into view.

5.7 Fail the air data inputs by opening the appropriate system circuitbreakers. Monitor the relevant GPS status pages and verify that TAS,IAS, and ALT fields are cleared. Enter the data manually and verifyproper manual data entry is achieved.

5.8 While GPS status is displayed, tune and transmit on each VHFCOMM for 30 seconds on the following frequencies. 121.150, 121.175,121.200, 131.250, 131.275, and 131.300. Verify that no interference isnoted in regard to GPS reception or flight instrument displays.

5.9 Verify that no objectionable EMI or RFI exists between the GPSsystem and the other aircraft system and vice versa.

5.10 Evaluate the GPS installation for proper identification of allcomponents, correct placarding and identification, visibility ofannunciators and displays (day and night ), plus correct switchfunctions and dimmer operation.

5.11 Verify that operation of the GPS and the description of the system isaccurately presented in the AFM supplement.

5.12 Select and fly an appropriate NPA to check operation RAIMprediction function and correct sequencing of modes


CERTIFICATION:LAME SIGN:LIC. NO:CERT. OF APPROVAL:DATE:Note: As some of these tests may not be possible on all GPS receivers there is a need to cross referenceto TSO C129a. PAGE 3 OF 3

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