CAAP 35-1(0)
Civil Aviation
Advisory Publication
December 1997
Global Positioning
System (GPS):
general installation guidelines
This publication is only
advisory but it gives the
CASA preferred method for
complying with the Civil
Aviation Regulations.
The relevant regulations
It is not the only method,
but experience has shown
that if you follow this
method you will comply
with the Civil Aviation
Regulations.
Always read this advice in
conjunction with the
appropriate regulations.
Contents…
Introduction
2
Approval Criteria
3
Requirements
applicable
to all installations
3
Specific Installation
Requirements:
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
•
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 that
need to be considered to ensure that a GPS receiver
installed in the aircraft is suitable for its purpose and is
installed in accordance with the Design Standards
applicable to the aircraft.
Status of this CAAP
This is the first CAAP to be written on GPS receiver
installation and it supersedes AAC 6-26 Issue 3.
For further information
Contact the CASA Airworthiness District Office closest to
you.
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CAAP 35-1(0): Global Positioning System (GPS):
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Introduction
1. This CAAP describes an acceptable means, but not the
only means, of meeting the requirements of the Design
Standards applicable to the aircraft when dealing with a
design for the installation of GPS equipment into
Australian registered aircraft. Alternative means of
compliance need to be fully justified by the person
submitting the design for approval. Persons choosing to
adopt the means of compliance outlined herein are
expected to comply with all the requirements and
unacceptable modification of any part of this CAAP would
result in a failure to obtain approval for the design.
2. A brief history of GPS and an explanation of terms is
included at Appendix 1.
3. This CAAP also provides information and guidance
on the airworthiness requirements for GPS equipment
under the provisions of CAR 21, CAR 42, CAR 138 and
CAR 232A.
4.
The topics covered are:
(a) the installation of GPS equipment as a nonapproved Supplemental en-route aid to
navigation in aircraft operating under the Visual
Flight Rules (VFR);
(b) the installation of GPS equipment as an approved
Supplemental en-route aid to navigation in
aircraft operating under the Instrument Flight
Rules (IFR);
(c) the installation of GPS equipment as an approved
Primary Means aid to navigation in IFR
operations including “GPS Arrivals”, “GPS/DME
Arrivals”;
(d) the installation of GPS equipment as an approved
Primary Means aid to navigation for
oceanic/remote area operations;
(e) the installation of GPS equipment as an approved
Supplemental aid for Non-Precision Approaches
(NPA), as published in the Australian
Aeronautical Information Publication (AIP); and
(f) the requirement for, and preparation of, Aircraft
Flight Manual Supplements (AFM Supp).
CAAP 35-1(0): Global Positioning System (GPS):
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5. Installation of GPS receivers into aircraft involves
changes to the aircraft configuration which can be achieved
by either:
(a) an original modification design approved in
accordance with CAR 35;
(b) an applicable STC installed in accordance with the
instructions contained in the accompanying data
pack. If insufficient information is available, or
the procedures detailed within the data pack are
not followed, or cannot be followed due to a
previous modification, then the installation is to
be approved in accordance with CAR 35; or
(c) the aircraft manufacturer’s Service Bulletin (SB).
Any variation from the procedures or design
detailed in the SB is to be approved in accordance
with CAR 35.
Aircraft airworthiness
standards
6. CASA has determined that the Design Standards that
should apply for GPS installations are those specified in
FAR 23 Amdt 52, FAR 25 Amdt 91, FAR 27 Amdt 34, FAR
29 Amdt 41. For operations under the IFR, GPS equipment
is required to have TSO C129/C129a or CASA approved
equivalent authorisation. Appendix 2 provides details of
the classes of TSO C129/129a equipment.
APPROVALS REQUIRED
7. Appendix 3 details the approvals required for each
type of installation.
Requirements applicable
to all installations
8. The design of the installation is required to comply
with those Design Standards that are applicable to the
aircraft being modified. The general requirements listed
below, as well as those listed for each different installation,
provide guidance to assist the designer in maintaining
those standards. These are the minimum requirements to
be met for an installation to be accepted and the aircraft
approved for specific operations.
AIRCRAFT INSTALLATION
9. The need to minimise pilot workload and facilitate
easy access and operation of the controls during critical
phases of flight is essential. Adherence to established
rules for the location of navigation displays and controls
will assist in achieving this goal.
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CAAP 35-1(0) — Global Positioning System (GPS):
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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 of
installation drawings and wiring diagrams, should be used
to ensure the correct installation of the system into a
particular aircraft. The holder of a CAR 35 Instrument of
Appointment (IoA) or delegation approving the design of
the modification should take particular note of any
manufacturer’s installation limitations, such as antenna
positioning, electrical system distribution and loading,
structural requirements and cockpit layout. Justification
for any deviations from the manufacturer’s limitations
may need to be provided for assessment by CASA. Prior
to final approval the holder of a CAR 35 IoA or delegation
is to ensure that the equipment, after installation, functions
properly.
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 be
found in FAA AC 43.13-2A.
12. The installation in an Australian registered aircraft is
to be performed in accordance with CAR 42ZC within
Australia and CAR 42ZD outside Australia.
GPS FAILURE INDICATION
13. A clearly visible and unambiguous failure indication is
to be provided to indicate to the flight crew when the GPS
equipment has failed or is unable to perform position
calculations. The failure/status indications provided by
approved GPS equipment as part of the normal display
satisfy this requirement if that display is clearly visible to
the pilot.
14. All instruments providing a display of GPS derived
information must have a means of indicating the failure of
that source of information, e.g. an “off flag”.
Note:
Presentation of a failure/status annunciation does not
require removal of navigation information from the
navigation display.
Reference: FAR 23.1309/1321/1322, FAR 25.1309/
1321/1322, FAR 27.1321/1322 or FAR 29.1309/1321/1322
refer. AC 23-1309-1A provides additional information.
CAAP 35-1(0): Global Positioning System (GPS):
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NAVIGATION SOURCE ANNUNCIATOR
15. If the GPS equipment installation supplies any
information to a display such as a Horizontal Situation
Indicator (HSI), Course Deviation Indicator (CDI), distance
display, electronic map, etc., then a navigation source
annunciator, clearly identifying the source of the
information currently displayed, is to be provided in clear
view of the pilot. Switch position is not a sufficient
indication of information source.
Note:
This requirement originates from the need to ensure that
hazardously misleading information is not presented to
the pilot. A visual cue is required to confirm the source
of the navigational information being displayed.
Reference: FAR 23.1309, 25.1309, 27.1309 or 29.1309; subsection b.3.
AUTOPILOT/FLIGHT DIRECTOR COUPLING
16. Only permanent GPS equipment installations are to be
coupled to an autopilot and/or flight director. Hand held
units carried on or mounted in adapter cradles/mounts in
the aircraft are not be used in this configuration. The
aircraft is to be flight tested to ensure that the GPS
receiver/autopilot coupling functions as intended. If
multiple steering input sources are available to an
autopilot, clear and unambiguous visual indications are to
be 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 35
IoA, or delegation, is to specify the maintenance
requirements for the installation, e.g. periodic maintenance
for installed internal batteries, for inclusion into the aircraft
system of maintenance or a log book statement. This
should be in compliance with manufacturer’s
recommendations and any variation may need to be
justified.
NAVIGATIONAL DATA BASE MAINTENANCE
18. It is the pilot’s responsibility to ensure that the
database to be used for the particular phase of flight is
current. The updating of the database is a maintenance
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CAAP 35-1(0) — Global Positioning System (GPS):
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function and may require the authorisation of the person,
other than a LAME, performing the update. Additional
information regarding obtaining a maintenance authority
can be obtained from the local CASA office.
AIRCRAFT FLIGHT MANUAL SUPPLEMENT (AFM SUPP)
19. An appropriate AFM Supp, containing the limitations
and reference to the manufacturer’s operating procedures
applicable to the equipment installed, should be submitted
to CASA or Authorised Person for approval under CAR
138.
20. GPS equipment fitted only for VFR Supplemental enroute navigation does not require a AFM Supp.
21. The layout for a AFM Supp should follow the format
for the approved flight manual and include the following:
(a) General. This section is to contain a brief general
description of the particular GPS equipment
installation, e.g. receiver type, details of remote
annunciator etc.
Note:
Full details of the system installed in the aircraft,
including reference to the CAR 35 approval
documentation controlling the incorporation, are
contained in the aircraft log book.
(b) Limitations. Any limitations on the use of the
system, e.g. in the integrated mode, are to be
specified.
(c) Emergency/Abnormal Procedures. Procedures
detailed in the manufacturer’s handbook would
be sufficient (if applicable).
(d) Normal Procedures. This section contains either
operating procedures in terms of manufacturers
instructions or reference to the manufactures
operating manual, which would then be required
to be available to the aircrew at all times whilst in
flight. Instructions detailing the method of
operation of the integrated system in the coupled
mode is to be included. Details are to be provided
explaining all the functions and indications
provided by the remote annunciators, switches
and placards etc.
(e) System Description. Details of the integration of
the GPS equipment into the aircraft system/s are
to be provided in this section.
CAAP 35-1(0): Global Positioning System (GPS):
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Reference: FAR 23.1581-1585, 25.1581-1585, 27.1581-1585 or
29.1581-1585.
VFR supplemental
navigation system —
domestic enroute
EQUIPMENT STANDARD
22. GPS equipment is not yet an approved aid to
navigation for use under the VFR and can only be used as
a supplemental navigation system.
Note 1: Whilst there are no equipment standards for VFR
Supplemental GPS, the output from this type of
equipment may be used to provide azimuth information
for the autopilot however the receiver must be
permanently mounted
Reference: FAR 23.1329, 25.1329, 27.1329 or 29.1329.
Note 2: The equipment display should be illuminated to ensure
readability 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, when
approving the design of GPS equipment installations for
operations limited to VFR, is to ensure that the design does
not constitute a hazard to the aircraft or crew.
Reference: FAR 23.1351/1431, 25.1353/1431, 27.1351 or
29.1353/1431.
VFR LIMITATION PLACARD
24. If GPS equipment that does not have TSO C129/C129a
or equivalent authorisation a placard stating that:
“The GPS equipment fitted is not an approved aid to
navigation”
is to be installed in clear view of, and easily readable, by
the pilot.
Note:
GPS has not been approved as an aid to navigation
under the VFR as a result of concerns over the following
issues:
(a) there are no design standards apart from the TSO
C129/129a,
(b) selected equipment may not be appropriate for the
task,
(c) no required purpose under the VFR, and
(d) without a approved RAIM facility the navigational
data produced by the system cannot be guaranteed
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CAAP 35-1(0) — Global Positioning System (GPS):
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because the satellite availability and accuracy are
subject to change.
Reference: FAR 23.1541, 25.1541, 27.1541 or 29.1451.
IFR supplemental
navigation system
EQUIPMENT STANDARD
25. GPS navigation equipment, to be approved as a
Supplemental Navigation System for oceanic en-route and
domestic en-route operations must have a TSO-C129 or
C129a or CASA approved equivalent authorisation.
SYSTEM INSTALLATION
26. The holder of a CAR 35 IoA, or delegation, when
approving the design of GPS equipment installations for
IFR en-route supplemental navigation, is to ensure that the
design complies with the minimum requirements listed in
the general requirements section of this CAAP (paragraph
9 to 21 inclusive), together with those detailed herein.
SYSTEM COMPATIBILITY
27. The GPS equipment installation must not be a source
of electromagnetic interference, nor be adversely affected
by electromagnetic interference from other equipment in
the aircraft.
28. The interfaces with other aircraft equipment are to be
designed such that normal or abnormal use of the installed
GPS equipment does not adversely affect the operation of
other equipment, nor will normal or abnormal operation of
other equipment adversely affect the GPS equipment
operation.
29. The system compatibility, as described, should be
confirmed by functional testing in accordance with this
CAAP (paragraph 31) and the references below.
Reference: FARs 23. 1309/1431, 25. 1309/1431, 27. 1309/
1431 or 29.1309/1431 refer. Additional information on
testing 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 35
IoA, or delegation, is to determine the extent of testing that
is to be conducted for every installation to verify that the
installed GPS equipment operates correctly. To confirm
CAAP 35-1(0): Global Positioning System (GPS):
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correct operation of the installation the following tests, as a
minimum, are suggested:
(a) ensure all operating modes of the GPS equipment
operate in accordance with the approved design;
(b) ensure the coupled function of other equipment
connected to the GPS equipment operates in
accordance with the approved design;
(c) ensure the various failure modes and associated
annunciations (such as loss of electrical power,
loss of signal reception and GPS equipment failure
etc.) operate in accordance with the approved
design;
(d) ensure the displayed GPS derived navigation
parameters on coupled cockpit instruments (if
connected) 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 receiver
display;
(e) ensure all switching and transfer functions,
including electrical bus switching, pertaining to
the GPS equipment installation function as
intended in the approved design.
(f) demonstrate satisfactory electromagnetic
compatibility requirements between the GPS
equipment installation and other onboard
equipment. Some installations may exhibit
significant EMI/EMC problems brought about by
the age and brand of electronic equipment fitted
to the aircraft or by the lack of room needed to
mount the GPS antenna in an optimum position.
Testing for harmonic interference is to be
performed to determine the effectiveness of the
design. Filtering of the outputs of
communications transmitters, as an example, may
be required to obtain a satisfactory level of
performance.
Note 1: The GPS signal is typically below the value of the
background noise. Electrical noise in the vicinity of the
antenna can adversely affect the performance of the
system. Antenna installation in close proximity to Traffic
Alert and Collision Avoidance System (TCAS), satellite
communication (SATCOM), DME and other transmitting
antennas (particularly ‘L’ band) are to be carefully
evaluated for potential mutual interference.
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CAAP 35-1(0) — Global Positioning System (GPS):
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Intermodulation effects are possible between multiple
channel SATCOM installations and GPS receivers.
Note 2: Harmonic interference from VHF transmissions on, but
not limited to, 121.150, 121.175, 121.200, 131.250,
131.275 and 131.300 MHz may adversely affect
reception of the GPS signal if sufficient attenuation of
harmonics is not provided.
Note 3: A minimum separation of 1.1 meters centre to centre
between a GPS antenna and any ‘L’ band transmitting
antenna is essential to minimise interference. Similar
distances should be maintained to all other transmitting
antennae.
(g) ensure all GPS receiver controls are suitably
located so as to be readily accessible and useable
by the pilot and co-pilot (if required) from their
normal seated position in the aircraft’s normal
cruise configuration.
(h) ensure all controls, displays and annunciations
relating to the GPS equipment are clearly visible
during day and night lighting conditions.
(i) to demonstrate that the GPS navigational
performance has not been adversely affected by
the installation in the aircraft and to confirm the
operation of the GPS equipment integration into
any aircraft system the holder of CAR 35 IoA, or
delegation, is to determine the need for, and the
extent of, flight testing. The purpose of flight
testing is to:
(i) ensure that continuity of navigation data is
maintained by ensuring that all satellites
above the mask angle are receivable in any
attitude or direction that can be sustained. If
necessary, the extent of any bad reception
areas need to be identified. A suggested flight
test evaluation sheet is attached at
Appendix 4.
(ii) validate the integration to the autopilot/flight
director to ensure the system operates
correctly in all phases of flight.
(iii) determine the suitability of the installed
system with regards to human factors
considerations.
CAAP 35-1(0): Global Positioning System (GPS):
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NAVIGATION DATA BASE
31. Systems used for en-route supplemental navigation do
not require the incorporation of a navigation data base,
however, if the facility is fitted the data used is to come
from a validated navigation data base supplied by an
approved source in accordance with the information
contained in the Australian AIP.
OTHER NAVIGATION EQUIPMENT REQUIRED
32. An aircraft employing GPS equipment for
supplemental IFR navigation is to be equipped with a Sole
Means navigation system.
AIRCRAFT FLIGHT MANUAL SUPPLEMENT (AFM SUPP)
33. In addition to the general requirements, the following
are required for IFR Supplemental installations:
Limitations. All limitations should be stated in the
appropriate section. The following limitations are
considered the minimum acceptable:
(a) The GPS equipment fitted is not approved as
either a primary means or sole means of
navigation.
(b) Users are cautioned that satellite availability and
accuracy are subject to change.
(c) The pilot is to monitor approved NAVAIDS and
utilise GPS derived position information as
supplemental only.
IFR primary means
navigation system —
domestic enroute
EQUIPMENT STANDARD
34. GPS navigation equipment, to be approved as a
Primary Means Navigation System is to, in addition to
having a TSO-C129 or C129a authorisation, or CASA
approved equivalent, also have pressure altitude data
(barometric aiding) automatically provided to the receiver
from an approved source, e.g. an encoding altimeter.
SYSTEM INSTALLATION
35. The holder of a CAR 35 IoA, or delegation, when
approving the design of GPS equipment installations for
IFR Primary Means navigation, is to ensure that the design
complies with the minimum requirements listed below.
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CAAP 35-1(0) — Global Positioning System (GPS):
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Any deficiencies highlighted during testing are to be
remedied prior to final approval.
SYSTEM COMPATIBILITY
36. The system compatibility requirements are the same
as detailed for IFR Supplemental Means, paragraphs 27 to
29.
37. In an integrated system that has the capacity to
display either GPS or ILS derived azimuth information on
a CDI/HSI, an automatic capability may be used to ensure
that when GPS information is being displayed and an ILS
frequency is selected on the primary VHF navigation
receiver (Nav1), the azimuth information being displayed
on the CDI/HSI reverts from GPS to ILS input
automatically. This system is acceptable provided that the
navigation source indicator clearly and accurately
identifies the source change.
Note:
Installations that utilise an illuminated switch for the
selection of navigation sources may not be acceptable.
TEST AND EVALUATION OF INSTALLATION
38. The suggested test and evaluation is the same as for
IFR Supplemental Means, paragraph 30.
BAROMETRIC ALTITUDE DATA (BARO-AIDING)
39. The provision of pressure altitude data from an
approved source (i.e. barometric aiding) is a mandatory
component of the GPS system required for approval of the
installation for IFR Primary Means navigation as detailed
in the Australian AIP. The holder of the CAR 35 IoA, or
delegation, is to ensure that:
(a) any interface used to convert altitude data from
one format to another does so in a manner that
does not corrupt or alter the integrity of that data;
and
(b) the altitude encoding device has TSO C88a or
equivalent authorisation.
40. The provision of altitude data to the GPS receiver
should not to be dependent on other, unrelated systems.
Note:
In some installations, altitude data is sourced from a
transponder dependent blind encoder via a data
serialiser. The transponder itself provides the additional
CAAP 35-1(0): Global Positioning System (GPS):
general installation guidelines
13
circuitry necessary for the data transfer. In this type of
installation, when the transponder is not powered,
altitude data is not available to the GPS and the GPS
system does not meet the requirements of IFR Primary
Means navigation. Duplication of the altitude encoder is
not required, however, additional circuit design would be
required to overcome this deficiency.
NAVIGATION DATA BASE
41. The data used for navigation is to come from a
validated navigation data base supplied by an approved
source in accordance with the information contained in the
Australian AIP.
OTHER NAVIGATION EQUIPMENT REQUIRED
42. An aircraft employing a GPS receiver for IFR Primary
Means navigation is to be equipped with a Sole Means
navigation system.
AIRCRAFT FLIGHT MANUAL SUPPLEMENT (AFM SUPP)
43. In addition to the general requirements, the following
is to be included for IFR Primary Means installations:
The following wording or similar should be included in the
general section:
This system may be used as a Primary Means of IFR
navigation for en-route and terminal operations
including GPS arrivals, GPS/ DME arrivals.
Limitations. All limitations should be stated in the
appropriate section. The following limitations are the
minimum considered acceptable:
(a) The GPS equipment fitted is not approved as a
sole means of navigation.
(b) The pilot is to monitor approved NAVAIDS and
compare the information with GPS derived
position information.
(c) Operation without RAIM is abnormal and the
navigation information provided should not be
relied on.
IFR primary means
navigation system —
oceanic/remote area
enroute
44. Refer to CAAP 35-2 Issue 0 (Currently under
development, however, in the interim FAA Document
8110.60 provides guidance for approval.)
14
IFR supplementary
means navigation
system for nonprecision approaches
CAAP 35-1(0) — Global Positioning System (GPS):
general installation guidelines
MINIMUM REQUIREMENTS FOR NPA INSTALLATIONS
45. GPS navigation equipment, to be approved as a
Supplementary Means Navigation System for NPAs:
(a) must have TSO-C129 or C129a, Class A1, B1, B3,
C1 and C3 only, or CASA approved equivalent
authorisation;
(b) be capable of approval for IFR Primary Means
Navigation System, Domestic En-route, as
detailed in this CAAP; and
(c) comply with the minimum requirements of this
section or an alternate, equivalent level of safety.
RECEIVER/CONTROL PANEL PLACEMENT
46. To safely execute a GPS non precision approach a pilot
must have essential navigation information including
azimuth indication, waypoint information and GPS
receiver message functions presented in a clear and legible
format. Ready access to the GPS receiver during the
approach is required by the pilot or, in the case of two pilot
operations, the non flying pilot to enable the receiver to be
operated correctly.
47. An integrated system that has an automatic capacity
to switch displays between either GPS or ILS derived
azimuth information on a CDI/HSI should not be used.
Note:
Having this facility would prevent a pilot from conducting
a NPA and having an ILS frequency selected, as an
alternative, at the same time.
48. The following paragraphs provide guidance on
equipment location and access for the common operational
configurations.
Reference: FAR 23.1321/1322, 25.1321/1322, 27.1321/1322
or 29.1321/1322.
SINGLE PILOT OPERATION
49. For single pilot operations the azimuth, waypoint and
message information may be provided by a display
contained within the receiver. The GPS annunciator panel,
which displays MSG, WPT, HOLD and APP lights, is to be
in the pilot’s primary field of view.
CAAP 35-1(0): Global Positioning System (GPS):
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50. Receiver Only: The receiver/control panel display is
to be mounted in such a position as to:
(a) provide the pilot clear and unobstructed view of
the data screen allowing the pilot to see the
display enabling the extraction of essential
navigational information including azimuth
indication, waypoint information etc.;
(b) be viewable from the pilot’s normal seated
position and be within the primary scan area; and
(c) ensure all controls that are normally adjusted in
flight are readily accessible.
Note:
For single pilot operations without integrated electronic
displays, the placement of the GPS receiver in the
central pedestal is not acceptable.
51. Receiver with remote CDI/HSI display: If fitted, the
remote display is to be mounted on the instrument panel
within the pilot’s primary field of view. This may be
provided by a dedicated CDI/HSI type instrument or as a
switched input to a multiple display. The GPS annunciator
panel, which displays MSG, WPT, HOLD and APP lights,
is to be on the primary instrument panel. The
receiver/control panel display is to be mounted in such a
position as to:
(a) provide the pilot clear and unobstructed view of
the data screen allowing the pilot to see the
display enabling the extraction of essential
navigational information including azimuth
indication, waypoint information etc.;
(b) be viewable from the pilot’s normal seated
position and be within the primary scan area; and
(c) ensure all controls that are normally adjusted in
flight are readily accessible.
Note:
For single pilot operations without integrated electronic
displays, the placement of the GPS receiver in the
central pedestal is not acceptable as it does not allow
the pilot a clear and unobstructed view of the data
window.
TWO PILOT OPERATIONS
52. For aircraft operations that require two pilots, the
display of GPS derived navigation information is to be
duplicated to the extent necessary to enable either pilot,
when in control of the aircraft, to view the azimuth
navigational information within their primary viewing
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CAAP 35-1(0) — Global Positioning System (GPS):
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area. Receiver/control panel placement is to be central and
accessible to either pilot to enable the non-flying pilot to
effectively operate the equipment and utilise the receiver
display, where necessary, to perform the cross checking
function. The GPS annunciator panel, which displays
MSG, WPT, HOLD and APP lights, must be located such
as to be either clearly visible to both pilots or duplicated on
the respective instrument panels.
Note:
In some installations it may not be feasible to provide
duplicate displays of GPS derived information.
Operators utilising installations where the navigation
displays between the flying pilot and non-flying pilot
differ should provide adequate description of the method
of operation in the AFM Supp, Operations Manual and in
the flight crew checklist (as appropriate).
SINGLE/DUAL PILOT OPERATIONS WITH INTEGRATED
ELECTRONIC DISPLAYS
53. Where an aircraft is fitted with electronic
multifunction displays that form part of a Flight
Management System (FMS) and the GPS is integrated into
that FMS, the GPS control panel is to be placed in a
position that ensures all controls that are normally
adjusted 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 the
installation modification to provide aircraft power to the
GPS equipment from an essential bus (if the aircraft is
equipped with such). If this design approach is taken an
electrical load analysis must be conducted to ensure the
minimum requirements for battery power reserve are met
given 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 an
added alert facility the audio output from the GPS receiver
should be connected to the aircraft audio system in a
manner that allows pilot selection of tone and volume.
CAAP 35-1(0): Global Positioning System (GPS):
general installation guidelines
17
TEST AND EVALUATION OF NPA INSTALLATION
56. As part of the design approval the holder of the CAR
35 IoA, or delegation, is to determine the extent of testing
that is to be conducted for every installation to verify that
the installed GPS equipment, intended for NPAs, can be
operated in accordance with the approved design.
NAVIGATION DATA BASE
57. The data used for NPAs shall come from a validated
navigation data base, supplied by an approved source in
accordance, with the current Australian AIP information.
AIRCRAFT FLIGHT MANUAL SUPPLEMENT (AFM SUPP)
58. In addition to the information detailed for IFR Primary
Means Navigation System, Domestic En-route AFM Supp,
the following should be included for Supplementary NPA
installations:
General Section: The following wording or similar should
be added in the general section:
This system may be used for approved Supplemental
Non-Precision Approaches as published in the AIP.
Limitations: The following is acceptable:
NPA procedures are not to be conducted without
RAIM.
Summary of approval
procedures
59. All installations of GPS equipment into aircraft are
aircraft modifications. The person having an IoA or
Delegation under CAR 35, when approving the
modification, shall ensure that the design satisfies the
design standards specified.
60. GPS equipment intended for VFR Supplemental use
only does not require TSO-C129/C129a or equivalent
authorisation and as such is not an approved aid to
navigation.
61. GPS equipment approved for Supplemental Means
under IFR use is to have either TSO-C129 or C129a or
CASA approved equivalent authorisation.
62. GPS equipment approved for Primary Means under
IFR use shall have TSO-C129 or C129a or CASA approved
equivalent authorisation together with automatic
18
CAAP 35-1(0) — Global Positioning System (GPS):
general installation guidelines
barometric aiding from an approved source. The
receiver/control panel is to be installed in clear view of the
pilot and capable of unobstructed operation from the
pilot’s normal seated position.
63. GPS equipment approved for Supplementary Means
NPA use shall have TSO-C129/129a or CASA approved
equivalent authorisation and automatic barometric aiding
from an approved source. The receiver/control panel
location, together with any additional displays will be
determined according to the crew requirements of the
aircraft and the existing avionics suite.
64. Where a AFM Supp is required, the proposed AFM
Supp should form part of the design package
65. The need for flight testing is to be determined by the
CAR 35 IoA holder or delegate.
Other references
•
RTCA Inc Document DO-208
•
ICAO Circular 267-AN/159 Guidelines for the
Installation and Operational Use of the Global
Navigation Satellite System (GNSS)
•
Federal Aviation Administration (FAA) Technical
Standard Order (TSO) C129/129a Airborne
Supplemental Navigation Equipment Using The Global
Positioning System (GPS)
•
FAA TSO C88a Automatic Pressure Altitude Reporting
Code 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 of
Aircraft Instrument Malfunction Indicators
•
FAA AC 20-138 Airworthiness Approval of Global
Positioning System (GPS) Navigational Equipment for
Use as a VFR and IFR Supplemental Navigational
System
•
FAA AC 23-1309-1B Equipment, Systems and
Installations in FAR 23 Aircraft
•
FAA AC 25-10 Guidance for Installation of
Miscellaneous Nonrequired Electrical Equipment
•
FAA AC 25-1309-1A System Design Analysis
•
FAA AC 27-1 Certification of Normal Category
Rotorcraft
CAAP 35-1(0): Global Positioning System (GPS):
general installation guidelines
19
•
FAA AC 29-2A Certification of Transport Category
Rotorcraft
•
FAA AC 43-13-2A Acceptable Methods, Techniques
and Practices Aircraft Alterations
•
FAA Notice 8110.60 GPS as a Primary Means of
Navigation for Oceanic/Remote Operations
•
Who this CAAP applies to
•
Persons approving the design of aircraft modifications
involving the installation of TSO C129/129a or other
CASA approved GPS receivers.
•
Persons or organisations holding accepted
Supplementary Type Certificates (STC) dealing with
the installation of GPS equipment.
•
Certificate of Registration (CoR) holders of aircraft
having GPS receivers fitted.
20
CAAP 35-1(0): Global Positioning System (GPS):
general installation guidelines
APPENDIX 1
SYSTEM 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 an
aid to radio navigation which uses precise range measurements from the GPS satellites to
enable accurate position fixes to be determined anywhere in the world. The satellites’
measured orbital parameters (ephemeris data) are combined with precision onboard timing
signals and broadcast as a composite signal. The receiver processes this information to
determine its position in space.
GPS position information is expressed in the Cartesian, earth-centred, earth-fixed coordinates as specified in the World Geodetic System 1984 (WGS-84). Whilst there are other
systems 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., are
computed from the aircraft’s latitude/longitude and the location of the waypoint. Course
guidance is usually provided as a deviation from the desired track of a Great Circle course
between 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, continuity
of 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 of
the information supplied by the total system. This includes the ability of the system to
notify the pilot if a satellite is radiating erroneous signals.
Receiver Autonomous Integrity Monitoring (RAIM). A technique whereby a civil GPS
receiver/processor determines the integrity of the GPS navigation signals using only GPS
signals or GPS signals augmented by altitude information. This determination is achieved
by a consistency check among redundant pseudorange measurements. At least one other
satellite, in addition to those required for navigation, is required.
A further enhancement to this technique is Fault Detection and Exclusion (FDE). This
enables the receiver to identify which satellite is in error and to exclude it from the
navigation solution. This capability requires an additional satellite bringing the minimum
number to six.
For the particular phase of flight being undertaken, i.e. en-route, approach etc., there is an
allowable positional tolerance. When the calculated positions from the various
combinations of satellites are compared the differences between each calculated position
should not exceed that tolerance. If this tolerance is exceeded a ‘RAIM Warning’ indication
is given by the receiver. Situations may arise when the receiver will indicate that RAIM has
been lost (display of this message is receiver dependent). This occurs when not enough
satellites 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. This
has the benefit of reducing the minimum satellite count to four (or five if FDE is included).
CAAP 35-1(0): Global Positioning System (GPS):
general installation guidelines
21
Receivers that have TSO C129/129a authorisation or CASA approved equivalent have
RAIM or an equivalent integrity monitoring system. For non TSO compliant receivers,
rudimentary GPS integrity checking can be achieved by comparing the navigational
information 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 an
indication of the ability of the system to provide useable service within the specified
coverage area. It is a function of both the physical characteristics of the environment and
the technical capabilities of the transmitter facilities.
GPS availability is the system’s capacity to provide the number of satellites required for
position fixing. A minimum of three satellites need to be in view to determine a two
dimensional position, whilst four are required to establish an accurate three dimensional
position.
System Accuracy. Each satellite transmits a unique code string containing a precise time
signal together with the satellite identifier. The distance from that satellite to the GPS
receiver is calculated by utilising this precise time signal. The receiver computes its position
by 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 equipment
characteristics and various geometric and atmospheric factors. Many of these errors are
compensated by mathematical algorithms built into the receiver, however some cannot be
corrected due to their variable nature, e.g. ionospheric effects.
Selective Availability (SA) is a technique used by the US DoD for denying the full accuracy
of the system to other than approved (military) users. SA is achieved by artificially creating
a 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, and
300m 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 to
perform its function during the intended operation. Although the GPS satellite system has
been declared FOC with 24 satellites in orbit, the possibility exists that breakdowns will
occur. 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 at
particular locations at certain times. The US DoD has guaranteed 24 satellites will be
available 70% of the time.
Equipment Classes. GPS equipment which holds TSO authorisation is identified by
equipment class. There are three main classes of GPS equipment which are further divided
to form 10 sub-classes. Class A relates to stand-alone GPS equipment, while Classes B and
C relate to GPS equipment as part of a multi-sensor navigation system. Appendix 2
provides a summary of the 10 sub-classes. For a more detailed explanation of the various
classes, 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 means
navigation system could include one (stand alone installation) or several sensors possibly of different
types (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 or
phase of flight, meets accuracy and integrity requirements, but need not meet full
availability and continuity of service requirements. Safety is achieved by either limiting
flights to specific time periods, or through appropriate procedural restrictions and
operational requirements.
Note:
This is particularly significant because the GPS provides wide area coverage, whereas other
approved navigation aids such as VOR/DME offer distributed system redundancy. For example, a
GPS measurement signal failure reduces or eliminates the GPS navigation capability over a wide area
whereas, a single VOR/DME failure affects only a small area.
Supplemental Navigation System. A navigation system that is used in conjunction with a
sole means navigation system. Approval for supplemental means for a given phase of flight
requires that a sole means navigation system, for that phase of flight, is on board and is
monitored and cross checked. Amongst the navigation system performance requirements
for a given operation or phase of flight, a supplemental means navigation system is to meet
the accuracy and integrity requirements for that operation or phase of flight; there is no
requirement to meet availability and continuity requirements.
Hand Held Equipment. Equipment that is portable and operates off an internal battery and
an integrated (internal or external) antenna. There may be provision for a remote antenna
that is temporarily attached to the aircraft using suction cups, clamps etc. No modification
is made to the aircraft structure or electrical wiring. Since hand held GPS receivers, at this
time, do not provide a RAIM type function for integrity checking they are not an approved
aid to navigation and their use is limited to VFR supplemental en-route. If a hand held unit
is to be used for VFR Supplemental navigation, CASA strongly recommends that a type
identified by the manufacturer as being suitable for aviation purposes is used.
Note: Hand held units not identified as suitable for aviation purposes generally are
unable 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 and
connected to an external antenna, or
(b) a portable unit that is fitted to a dedicated cradle which is permanently
mounted in the aircraft, designed to be provided with aircraft power and, if
required, 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 a
different meaning within the TSO-C129 or C129a.
Integrated Equipment. Equipment that is permanently fitted to the aircraft, supplied
aircraft power and is connected to an external antenna. The unit provides input to other
aircraft systems and/or receives input from other aircraft systems.
Multi sensor systems where GPS is one of many inputs to a flight management system are
the subject of a separate CAAP.
CAAP 35-1(0): Global Positioning System (GPS):
general installation guidelines
23
APPENDIX 2
TECHNICAL STANDARD ORDER (TSO) C129 - EQUIPMENT CLASSES
Equipment Characteristics
Class
Stand
Alone
A1
X
A2
X
MultiSensor
Auto
Pilot
Req
RAIM
Equipment Capability
RAIM
Equip
Enroute
Terminal
Non
Precision
Approach
X
X
X
X
X
X
X
B1
X
X
X
X
B2
X
X
X
X
B3
X
X
X
X
B4
X
X
X
X
C1
X
X
X
X
X
C2
X
X
X
X
X
C3
X
X
X
X
C4
X
X
X
X
X
X
X
X
24
CAAP 35-1(0) — Global Positioning System:
general installation guidelines
APPENDIX 3
APPROVALS REQUIRED
VFR
IFR
CAR 35 (2)
CAR 138 (3)
Hand Held
No
No
Non
Integrated
(Non TSO)
Yes
No(1)
Integrated
(Non TSO)
Yes
No(1)
Non
Integrated
(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 VFR
and reference to vendor manual is suggested.
Note 2: Log book compliance with CAR 42U should not be completed until all design
documentation is available and CAR 35 approval issued.
Note 3: The AFM Supp must contain reference to the CAR 35 approved document upon which the
design/operating limitations and conditions are based. A draft AFM Supp may be submitted for
consideration under CAR 138 (1)(a) in anticipation of compliance with CAR 42U. However, the
design document and AFM Sup must align in their final form to allow CAR 138 approval and issue
of the Supp to the aircraft; any associated Operation Manual amendment should occur at the same
time, para 9A of CAO 20.18 refers.
CAAP 35-1(0): Global Positioning System (GPS):
general installation guidelines
25
APPENDIX 4
FLIGHT TEST EVALUATION SHEET
AIRCRAFT TYPE:
GPS SYSTEM:
1.0
……………. Model ……………… Registration VH-……
Type…………….. Model……………… S/N………………..
INTRODUCTION:
1.1
This document describes the flight test procedure designed to test the functions and
serviceability of the GPS installed in the aircraft
1.2
The checklist is required to be finalised by an appropriately rated LAME and
certified 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
2.1
Verify that the NAV data base as shown in the initialisation page is
current
2.2
Verify that after switch on the correct software version is displayed on
the relevant data page. Record software version: ………….
2.3
Verify that all annunciators introduced by this installation operate
correctly during self-test and dim checks.
2.4
Verify that all switching functions operate correctly, both on the GPS
system and external.
2.5
Perform any other test deemed necessary, and record test:-
PASS
FAIL
PAGE 1 OF 3
26
3.0
CAAP 35-1(0) — Global Positioning System:
general installation guidelines
PREFLIGHT GROUND TESTS
TEST INSTRUCTIONS
3.1
Create a flight plan appropriate to the flight test to be performed and
verify 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 the
appropriate data pages.
3.3
With GPS displayed on each relevant display, verify proper display of
deviations, To/From flags, bearing to waypoint, desired track and
distance to waypoint.
3.4
Verify that all switching functions operate correctly, both on the GPS
system and external.
3.5
Perform any other test deemed necessary, and record test:-
4.0
FUEL DATA EVALUATION
PASS
FAIL
PASS
FAIL
(AS REQUIRED)
TEST INSTRUCTIONS
4.1
Enter the known fuel state of the aircraft on the appropriate data page
including weight data if applicable.
4.2
Select the appropriate fuel page and check the fuel flow for
reasonableness with the aircraft’s fuel flow indicators. Verify the flow
data is reasonable for low, medium and high power settings, on the
ground and in flight.
4.3
Perform any other test deemed necessary, and record test:-
PAGE 2 OF 3
CAAP 35-1(0): Global Positioning System (GPS):
general installation guidelines
5.0
FLIGHT EVALUATION
TEST INSTRUCTIONS
PASS
5.1
Evaluate the accuracy of the GPS by recording latitude, and longitude
of geographic points such as VORs, DMEs, or runway touch down
points or thresholds, on a flight of at least 1 hour. Data should be
taken ( 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 data
presented corresponds to that displayed on the flight instruments.
5.3
Evaluate the steering response (roll steering) of the GPS when
coupled to the autopilot/flight director. Verify that leg changes do
not result in unacceptable over or undershoot conditions.
5.4
Evaluate the cross track or offset tracking performance. Verify that the
offset appears reasonable and meets stated accuracy
5.5
De select satellites and confirm appropriate annunciation Verify all
appropriate warning flags appear on the flight instruments. Reselect
satellites and verify the warning and flag conditions clear.
5.6
Fail the GPS system circuit breakers and verify the flight instrument
NAV flags come into view.
5.7
Fail the air data inputs by opening the appropriate system circuit
breakers. Monitor the relevant GPS status pages and verify that TAS,
IAS, and ALT fields are cleared. Enter the data manually and verify
proper manual data entry is achieved.
5.8
While GPS status is displayed, tune and transmit on each VHF
COMM for 30 seconds on the following frequencies. 121.150, 121.175,
121.200, 131.250, 131.275, and 131.300. Verify that no interference is
noted in regard to GPS reception or flight instrument displays.
5.9
Verify that no objectionable EMI or RFI exists between the GPS
system and the other aircraft system and vice versa.
5.10 Evaluate the GPS installation for proper identification of all
components, correct placarding and identification, visibility of
annunciators and displays (day and night ), plus correct switch
functions and dimmer operation.
5.11 Verify that operation of the GPS and the description of the system is
accurately presented in the AFM supplement.
5.12 Select and fly an appropriate NPA to check operation RAIM
prediction function and correct sequencing of modes
5.13 Perform any other test deemed necessary, and record test:-
27
FAIL
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 reference
to TSO C129a.
PAGE 3 OF 3