a. Pilot’s Guide.
An operations manual (pilot’s guide) describing the equipment, functions and procedures must be provided with the positioning and navigation equipment. It is essential that the pilot’s guide be complete, concise, and easy to understand. Have an FAA flight test pilot familiar with the equipment review the pilot’s guide and required training programs. This training program may be a series of manuals, a videotape, interactive CD-ROM, etc. Due to the inherent complexity in area navigation operations, it is important that these training materials are useful and help pilots learn to operate the equipment.
b. Quick Reference Guide.
A quick reference guide must be provided with the positioning and navigation equipment as a training aid for the operation of the positioning and navigation equipment. The guide should be evaluated by a flight test pilot familiar with the equipment.
18-11. Ground and Flight Test Plans (functional and EMI/EMC testing).
The applicant m ust submit the proposed ground and flight test plans to demonstrate the equipment performance (as described in chapters 18 through 22), regulatory compliance, and EMI/EMC testing.
Chapter 19. Inst alled Performance - Test (General).
19-1. Intended Function.
Assess the a bility for the equipment and aircraft combination to perform the intended function for the operation. The installed equipment may have the capability to perform an operation that is beyond the aircraft’s performance limit or current approval (or visa versa) and may require an AFMS/RFMS limitation. For example, a particular rotorcraft may only be approved for six degree steep angle approaches even though the installed equipment is capable of steeper angles.
19-2. Power Supply.
Assess all switching and transfer functions, including electrical bus switching, pertaining to the positioning and navigation installation.
19-3. Accuracy.
The accuracy of GNSS e quipment is not a function of the installation, and should not be evaluated for each GNSS or multi-sensor installation. The accuracy of the GNSS equipment will be demonstrated during the sensor evaluation, typically as part of a TSOA/LODA.
19-4. Human Factors.
a. Visibility of the controls, displays, and annunciators relating to the installation should be evaluated during day and night lighting conditions. No distracting cockpit glare or reflections m ay be introduced and all controls must be illuminated for identification and ease of use. Night lighting should be consistent with other cockpit lighting.
b. Layout of the installed equipment should be evaluated with emphasis on equipment controls, applicable circuit breakers (labels and accessibility), switching arrangement, and related indicators, displays, annunciators, etc.
c. Manual approach selection or manual tuning of the approach should override any automatic selection. Once an approach has been selected, appropriate feedback to the pilot
(e.g., display of approach name (including runway), airport and reference path identifier) must be given to indicate the approach has been correctly selected.
Chapter 20. Inst alled Performance - Test (GNSS).
20-1. Ground Test - GPS, GPS/SBAS, and GPS/GBAS.
20-1.1 Interference.
a. The lack of interference from VHF radios should be demonstrated on the completed GNSS installation by tuning each VHF transmitter to the frequencies listed below and transmitting for a period of 35 seconds while observing the signal status of each satellite being received. Degradation of individually received satellite signals below a point where navigation is no longer possible is not acceptable and will require that additional isolation measures be taken. Re-evaluation of installed VHF transceiver performance is not necessary if the filter insertion loss is 2 dB or less.
b. Evaluate the following VHF frequencies (25 kHz channels):
121.150 MHz 121.175 MHz
121.200 MHz 131.250 MHz
131.275 MHz 131.300 MHz
c. For VHF radios with 8.33 kHz channel spacing, evaluate the following additional VHF frequencies:
121.185 MHz 121.190 MHz
130.285 MHz 131.290 MHz
d. For installations on rotorcraft, ensure that the rotor blades do not interfere with the received signals. This problem has been experienced in some rotorcraft and varies with the rotation rate.
20-1.2 Antenna to Aircraft Navigation Reference Offset.
RTCA/DO-229D, paragraph 2.2.4.3.3 (Class Gamma equipm ent) and RTCA/DO-253C, paragraph 2.3.11.5.1 stipulates the equipment will support installations with the ability to compensate for the navigation center to antenna offset. If applicable, confirm that the antenna to aircraft center of navigation offset is appropriate to the installation for GPS/SBAS or GPS/GBAS equipment supporting LPV or GLS approach capability.
Note: The fact that the GNSS antenna is top-mounted can result in several feet of vertical difference between the antenna and the aircraft center of navigation, significantly larger than for ILS antennas. The center-of-navigation to wheel-crossing height should be evaluated for each installation. For most installations, a fixed vertical offset is adequate.
20-1.3 Sensor Installation.
No ground tests are recommended for the sensor. Guidance relating to the interface between the sensor and the navigation system can be found in chapters 13 and 14.
20-1.4 Stand-Alone Navigation Equipment Installation.
a. Navigation param eters displayed on cockpit instruments such as HSI, CDI, distance display, electronic flight instrument system, moving maps, FMSs, etc. should be evaluated against the criteria described in chapters 11, 13, and 14 of this AC.
b. Failure modes and associated annunciations, such as loss of electrical power, loss of signal reception, GNSS equipment failure, autopilot/FD response to flags, etc., should be reviewed against the criteria described in chapters 11, 13, and 14 of this AC.
20-2. Flight Test - GPS, GPS/SBAS, and GPS/GBAS.
20-2.1 Equipment Installation.
a. Verify navigation data continuity during norm al aircraft maneuvering for the navigation modes to be validated (e.g., bank angles of up to 30 degrees and pitch angles associated with take-off, departures, approaches, landing and missed approaches as applicable).
b. Verify the overall GNSS equipment operation to include at least the following:
(1) Hold at a designated waypoint;
(2) Intercept and track to or from a waypoint on a selected course;
(3) Turn anticipation;
(4) Waypoint sequencing;
(5) Selection of an approach;
(6) The general presentation of navigational data (depiction of the “TO” waypoint, distance to waypoint, estimated time of arrival, estimated time enroute, ground speed, etc.); and
(7) Evaluate the overall operation on all types of procedures or paths that the equipment supports (e.g., straight legs, DME arcs, and RF legs).
c. Verify that FTE can be maintained at less than 1.0 NM for enroute and approach transition operating modes, and less than 0.25 NM for non-precision approach, both with and without autopilot and/or FD use, as applicable. This test may not be necessary if the FTE has been previously established for the aircraft. One acceptable way of assessing FTE is to monitor the measured cross-track deviation using the navigation display provided.
d. The following issues sh ould be evaluated when the equipment is interfaced with a FGS. The objective of this paragraph is to ensure proper aircraft operation when the GNSS is interfaced with the aircraft’s FGS. If these issues cannot be addressed for a particular autopilot
(e.g., because the autopilot does not respond to flag indications), the GNSS equipment may still be installed, but either should not be connected to the autopilot, or have an appropriate AFMS/RFMS limitation that mitigates the issue.
(1) Evaluate steering response while the FD and/or autopilot is coupled to the GNSS equipment during a variety of different track and mode changes. This evaluation should include, as applicable, transition from enroute through the approach to missed approach modes and then back to enroute. Additionally, evaluate all available display sensitivities.
(2) Execute several fly-by turns with varying wind conditions for the FD and autopilot. Verify the equipment accomplishes the turn as a fly-by waypoint and discourages overshoot. Fly-by turns are turns where the equipment initiates the turning maneuver before sequencing the waypoint by an amount equal to the turn anticipation distance.
(3) Verify that the lateral maneuver anticipation supplied by the GNSS equipment is appropriate for the aircraft type. Verify that an appropriate annunciation of impending waypoint crossing is provided.
(4) Verify that execution of the Direct-To function with a resultant aircraft heading change does not overshoot and cause “S” turns. Re-initializing the Direct-To function after completion of most of the required track change may be an acceptable means of compliance for equipment which does not inherently account for the change in aircraft heading.
(5) Evaluate the autopilot response to a GNSS fault by pulling the circuit breaker for the GNSS equipment. This test should be done in all of the GNSS enroute and approach modes.
20-2.2 LPV and Precision Approaches.
a. For insta llations where the autopilot has not been modified and the GNSS equipment provides ILS-like deviations, conduct several approaches while flying raw data, FD and coupled to the autopilot, as applicable. The objective of this test is to ensure that the GNSS equipment interface is compatible with the aircraft; the objective is not to verify approach performance.
b. For installations where the autopilot has been modified, the autopilot lateral/vertical control channel performance has not been assessed, or non-standard deviations are provided (not ILS-like), then the approach performance will need to be evaluated per the latest revision of AC 23-17, AC 25.1329-1, AC 27.1329 contained in AC 27-1, or AC 29.1329 contained in AC 29-2 (or equivalent means).
c. For manual control to the approach flight path, the appropriate flight display(s) must provide sufficient information to maintain the approach path and make alignment with the runway or go-around without excessive reference to other cockpit displays.
d. Evaluate full-scale deflection while on approach to ensure the system operates properly.
e. Evaluate the FGS approach functionality to ensure compatibility with the gain scheduling employed by some FGSs during approaches. For example, some FGSs depend upon a radio altimeter, or, middle marker beacon passage inputs to enable a "glideslope extension" function to reduce "porpoising" or aerodynamic instability when coupled to a glideslope signal during the final approach phase. But WAAS LPV approaches do not have middle marker beacons so FGS response needs to be evaluated when incorporating LPV capability.
f. If the equipment uses barometric altitude input, verify that the equipment properly interprets the barometer reading. For equipment that requires manual entry of barometric correction, the entry should be accomplished during an approach to evaluate the crew workload.
g. Verify/assess all switching and transfer functions, including electrical bus switching, pertaining to the GNSS installation. Evaluate the aircraft system response during switches to all alternate navigation sources and ensure that the switch is accomplished as expected, that it is clearly annunciated, and that the switching itself does not induce any inaccurate guidance.
Verify any air data and inertial source select switches are appropriately reflected in the positioning and navigation equipment.
h. Review and verify, where appropriate, various failure modes and associated annunciations, such as loss of electrical power, loss of signal reception, GNSS equipment failure, FGS response to GNSS flags, etc. Verify that a warning associated with loss of navigation is accompanied by a visual indication within the pilot’s primary field of view.
i. A crew workload analysis when operating the GNSS equipment in association with other piloting requirements should be conducted during all phases of flight and found to be acceptable, including those non-normal procedures that can be evaluated in flight.
20-2.3 GPS/GBAS VDB Receiver Installa tion.
a. To verify non-interference (electromagnetic compatibility) between the VDB and VHF communications equipment, a flight test should be accomplished using the highest available VDB broadcast frequency, and transmitting VHF communication at 100 kHz above the VDB channel. Use 118.000 MHz for VHF communications equipment that cannot transmit below 118.000 MHz.
b. VDB receiving capability should be demonstrated in flight. Unlike ILS, where the ILS facility is always located in front of the aircraft on approach, a GPS/GBAS facility could be located anywhere with respect to the approach path. Therefore, the flight test should verify VDB signal reception at all angles relative to the airframe.
Chapter 21. Inst alled Performance - Test (RNAV Multi-Sensor Equipment).
21-1. Ground Test.
Refer to TSO-C115b/RTCA/DO-187 or TSO-C115c/RTCA-DO-283A, as appropriate, for RNAV multi-s ensor equipment ground test information.
21-2. Flight Test.
Flight tests are conducted to verify proper operation and accu racy of the multi-sensor equipment as installed in the aircraft (except for GNSS accuracy, see paragraph 20-2). Flight tests should include at least the following:
Note: Required flight evaluations for the first-time airworthiness approval of multi-sensor equipment are accomplished by the cognizant ACO unless specific tests are delegated by the ACO to a flight test pilot designated engineering representative (DER).
a. Evaluation to determine satisfactory EMC between the multi-sensor equipment installation and other onboard equipment (this test may be partially accomplished as a ground test).
b. Validate multi-sensor equipment navigational accuracy in each operating mode. In addition to overall system navigation performance, particular test requirements for navigational accuracy will vary depending upon the particular sensors integrated in the multi-sensor equipment and whether sensor accuracy performance data has previously been obtained. The performance of each navigation sensor should be evaluated separately and in combination with other sensors as applicable.
c. Initial certification for systems including a VOR/DME or multiple (scanning) DME sensor that has not been previously certified must be based upon a demonstration of system accuracy by recording (at not greater than 15 minute intervals) the VOR/DME and/or DME/DME sensor position and comparing it to the actual position during evaluation flights.
The latest revisions of AC 25-7 and AC 23-8 provide guidance on test distances from VOR and DME navigation aids. Recorded data should include sufficient signal parameters and sensor performance data to provide a clear indication of satisfactory sensor performance. The particular flight paths should be selected based upon an analysis of critical signal characteristics, station geometry, signal coverage (including limited station availability with acceptable range), aircraft movement, etc. The system should demonstrate its ability to detect poor signal conditions, inadequate navigation capability, recovery from in-flight power failure, etc. The auto-tune logic should be reviewed and tested to verify that ground stations are identified and tuned correctly.
d. Inertial systems that satisfy the criteria in 14 CFR part 121, appendix G and comply with Table 10 below from RTCA/DO-283A do not need further evaluation. Based on an evaluation of INS/IRU performance, the growth in position error after reverting to INS/IRU can be expected to be less than 2 NM per 15 minutes. Applicants that desire certification credit for 114
better perform ance should coordinate with their ACO for the requirements to demonstrate and document the performance.
Time Since Radio Updating (T) (hr) IRS/IRU 95% Error (NM)
0.0 to 0.5 hr 8*T
0.5 to 1.5 hr 4 Table 10. INS/IRU Accuracy After Loss of Radio Updating
e. Verify navigation data continuity during normal aircraft maneuvering for the navigation modes to be validated (e.g., bank angles of up to 30 degrees and pitch angles associated with approaches, missed approaches and departures).
f. Verify the overall operation of the multi-sensor equipment to include at least the following: the ability to create and modify a flight plan, hold at a designated waypoint, intercept and track to or from a waypoint on a selected course (Course to Fix leg), turn anticipation, waypoint sequencing, selection of an approach and the general presentation of navigational data (depiction of the “TO” waypoint, distance to waypoint, estimated time of arrival, estimated time enroute, ground speed, etc.).
g. Verify that FTE does not exceed 1.0 NM for enroute, 0.5 NM for approach transition and missed approach operating modes, and 0.25 NM for non-precision approach, both with and without autopilot and/or FD use, as applicable. This test may not be necessary if the FTE has been previously established for the aircraft. One acceptable way of assessing FTE is to monitor the measured cross-track deviation while either flying under autopilot control or flying manually using the navigation display provided.
h. If the equipment uses barometric input, verify that the equipment properly interprets the barometer reading. Special consideration should be given to manually entering a barometric correction.
i. Verify/assess all switching and transfer functions, including electrical bus switching, pertaining to the multi-sensor installation. The aircraft system response during any switch over to alternate navigation sources must be evaluated. Particular attention should be given to mode switching and transition requirements associated with the approach mode for equipment incorporating GNSS sensors.
j. Review and verify, where appropriate, various failure modes and associated annunciations, such as loss of electrical power, loss of signal reception, multi-sensor equipment failure, FGS response to GNSS flags, etc. Verify that a warning associated with loss of navigation is accompanied by a visible indication within the pilot’s primary field of view.
21-2.1 Interface to FGS.
a. Evaluate steering response while the FD and/or autopilot is coupled to the multi-s ensor equipment during a variety of different track and mode changes. This evaluation 115
116 should include, as applicable, transition from enroute through the approach to missed approach modes and then back to enroute. Additionally, evaluate all available display sensitivities.
b. Several fly-by turns should be accomplished with varying wind conditions for FD and autopilot. Verify the equipment accomplishes the turn as a fly-by waypoint and discourages overshoot. Fly-by turns are defined as turns where the equipment initiates the turning maneuver prior to sequencing the waypoint by an amount equal to the turn anticipation distance.
c. Verify that the lateral maneuver anticipation supplied by the multi-sensor equipment is appropriate for the aircraft type. Verify that if the multi-sensor equipment is coupled to an autopilot or on approach, an appropriate annunciation of impending waypoint crossing is provided.
d. Verify that execution of the Direct-To function with a resultant aircraft heading change does not overshoot and cause “S” turns that exceed the lateral path tracking FTE requirements.
e. Evaluate the autopilot response to a multi-sensor equipment fault by pulling the circuit breaker for the equipment. This test should be done in each of the sensor modes, if applicable.
21-2.2 GNSS Precision Approach.
a. For equipm ent that provides GNSS precision approach capability, or for equipment with non-standard navigation displays, conduct several approaches while flying raw data, FD only and coupled to the autopilot, as applicable. The objective of the test is to ensure that the multi-sensor equipment interface is compatible with the aircraft and is not a verification of approach performance. This objective is valid only for installations with existing and proven performance (e.g., GNSS providing ILS like deviations to replace or supplement an existing ILS). For installations where the autopilot has been modified or the autopilot lateral/vertical control channel performance has not been assessed, then the approach performance will need to be evaluated per the latest revision of ACs 23-17 or 25.1329-1, or equivalent means.
b. For manual control to the approach flight path, the appropriate flight display(s) must provide sufficient information without excessive reference to other cockpit displays, to enable a suitably trained pilot to maintain the approach path, make alignment with the runway or go-around.
Chapter 22. Inst alled Performance - Test (Baro-VNAV).
22-1. Introduction.
Paragraphs 22-2 and 22-3 describ e the installed performance test considerations for an initial approval. Subsequent installations are addressed in paragraph 22-4. An initial approval refers to the very first time an applicant presents a particular model of baro-VNAV equipment for FAA certification and airworthiness installation approval for an IFR navigation system.
Any new models of baro-VNAV equipment by the same manufacturer should undergo the same approval process as the original equipment unless it can be shown by analysis and test that the new model will function as well or better than the approved equipment.
22-2. Ground Test.
22-2.1 Lab/Bench Tests and Equipment Data Evaluation.
Nor mally the baro-VNAV equipment manufacturer will accomplish these actions for a certification design approval. This phase consists of the following:
a. Analysis of the manufacturer’s procedures for verification and validation of software and review of supporting documentation in accordance with the guidelines of RTCA/DO-178B.
b. Verification of compliance with appropriate environmental qualification standards such as RTCA/DO-160F.
Note: Previously certified baro-VNAV systems may have used an earlier RTCA/DO-160 revision. This equipment may still be installed within the provisions of its original certification.
c. Examination of the equipment’s display capabilities with emphasis on warning, caution, and advisory annunciations.
d. Analysis of failure modes.
e. Review of reliability data to establish that all probable failures are detected.
f. Evaluate the controls, displays, annunciations, and system behavior from a human performance perspective.
g. Review of installation and maintenance manuals.
h. Evaluation of operator's manual (pilot’s guide).
22-2.2 Aircraft Installation Data Evaluation.
Nor mally the baro-VNAV equipment manufacturer will provide an aircraft as a test bed for a first-time installation approval. The first-time installation approval will serve as a 117
basis for subsequent installation approvals on the sam e type of aircraft incorporating the same autopilot/FD system and for other aircraft installations not incorporating autopilot/FD interface with the baro-VNAV equipment. The following assessments must be made:
a. Review the installation drawings, wiring diagram, and descriptive wiring routing.
b. Examine the installed equipment cockpit layout of the with emphasis on equipment controls, applicable circuit breakers (labels and accessibility), switching arrangement and related indicators, displays, annunicators, etc.
c. Analyze the data flow diagram to review which equipment transmits what data to which other equipment.
d. Review the equipment installation structural analysis to ascertain whether all system components are satisfactorily attached to the basic aircraft structure.
e. Examine the electrical load analysis to verify that the system installation’s added electrical power requirements will not cause overloading of the aircraft’s electrical generating capacity.
f. Evaluate the integration with the associated lateral navigation equipment.
22-3. Flight Test.
22-3.1 Functional Flight Test.
a. Evaluate all baro-VNAV equipm ent operating modes.
b. Examine the interface (function) of other equipment connected to the baro-VNAV system.
c. Review various failure modes and associated annunciations, such as loss-of electrical power, loss of lateral navigation signals, baro-VNAV equipment failures, etc.
d. Evaluate steering response while the autopilot is coupled to the baro-VNAV equipment during a variety of lateral and vertical track changes including selection of baro-VNAV modes while operating at the maximum and minimum speeds approved for baro-VNAV use.
e. Evaluate displayed baro-VNAV navigation parameters on interfaced flight deck instruments such as an HSI, CDI, etc.
f. Assess all switching and transfer functions pertaining to the baro-VNAV equipment including high-power electrical loads and electrical bus switching.
g. Evaluate whether magnetic or radio frequency interference exists between the baro-VNAV equipment installation and other onboard equipment, or vice versa.
h. Evaluate the accessibility of all controls pertaining to the baro-VNAV sy stem installation.
i. Evaluate the display(s) and annunciator(s) visibility pertaining to the baro-VNAV system installation during day and night lighting conditions. No distracting cockpit glare or reflections may be introduced.
j. Analyze crew workload and determine acceptability when operating the baro- VNAV equipment.
22-3.2 Navigation Error Flight Test.
a. The initial certification of each baro-VNAV syst em to be used for IFR approach operations should be based on a system performance demonstration by recording the baro-VNAV equipment vertical guidance and comparing it to the actual aircraft position along a pre-established vertical flight path. This evaluation can be made by using:
(1) Theodolite observation;
(2) Comparison against ILS, GPS/SBAS LPV or LNAV/VNAV, or GPS/GBAS GLS glide path signals; or,
(3) By equivalent measuring techniques.
b. Data should be gathered using a variety of descent rates, angles, and lateral navigation source inputs available to the baro-VNAV system.
Note 1: GPS/SBAS LNAV/VNAV most closely emulates baro-VNAV performance.
Note 2: Some baro-VNAV implementations may provide ascent guidance as well for the missed approach segment or for applications other than approach operations. Data should also be gathered for ascent guidance if the equipment provides that capability.
c. The data should demonstrate that the appropriate accuracy criteria of paragraph
10-2.b are met on a 99.7% probability basis.
d. Flights should verify proper operation of caution indications and lateral navigation interface.
e. Normal flight maneuvers should not cause loss of system sensor inputs and the system dynamic response should be confirmed.
f. Evaluate any unusual flight technical errors or errors from using the autopilot and FD.