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(9) System Controls. All displays, controls, and annunciators must be readable under all normal cockpit conditions and expected ambient light conditions (total darkness to bright reflected sunlight). Night lighting provisions must be compatible with other cockpit lighting. All displays and controls must be arranged to facilitate equipment usage.
Controls that are normally adjusted in flight shall be accessible and properly labeled as to their function. System controls and displays shall be designed to maximize operational suitability and minimize pilot workload. System controls shall be arranged to provide protection against inadvertent system turnoff. Reliance on pilot memory for operational procedures shall be minimized.
(10) Navigation Data Base. For equipment incorporating a TSO-C129 GPS sensor, the multi-sensor equipment shall incorporate an appropriately updatable navigation data base (in the WGS-84 or NAD-83 coordinate datum). This data base must contain at least the following location information in terms of latitude and longitude with a resolution of 0.01 minute or better for the area(s) in which IFR operations are to be conducted: all airports, VOR’s (and VORTAC’s), NDB’s, and all named waypoints and intersections shown on en route charts. For equipment including a terminal mode, the data base shall also contain all named waypoints and intersections shown on terminal area charts, Standard Instrument Departures (SID’s) and Standard Terminal Arrival Routes (STAR’s). For equipment including an approach mode, the navigation data base must also include all waypoints and intersections included in published non-precision instrument approach (except localizer, LDA, and SDF) procedures. Instrument approaches must be conducted using a current database.
User entry or modification of navigation data base data shall not be possible. (This does not preclude the storage of “user defined data” within the equipment.) Additional data base coding, storage, and approach waypoint presentation requirements as specified in the applicable TSO’s must be provided. Navigation data bases shall meet the standards specified in sections 3, 4, and 5 of RTCA/DO-200, “Preparation, Verification and Distribution of User Selectable Navigation Data Bases” and sections 2 through 7 of RTCA/DO-201, “User Recommendations for Aeronautical Information Services.”
(11) Pressure/Barometric Altitude Inputs. If the multi-sensor equipment incorporates a Class B1, B2, C1, or C2 GPS sensor(s) and uses a barometric pressure/altitude input, that input must be appropriate to the equipment.
(12) Manufacturer’s Instructions. The multi-sensor equipment, including required antenna(s), shall be installed in accordance with the instructions and limitations provided by the manufacturer of the equipment.
c. IFR Airworthiness Approval. There are two types of IFR airworthiness approval which differ significantly as to test requirements and data analysis.
(1) First-Time IFR Airworthiness Approval (for a Particular Type of Multi- Sensor Equipment). This type of approval refers to the first time an applicant presents a particular (hardware and software configuration) model multi-sensor equipment integrating
26 Par 9 multiple navigation sensors for FAA airworthiness installation approval and certification for IFR navigation use. The first approval of particular multi-sensor equipment must be accomplished through the TC or STC process. Each new model of multi-sensor equipment by the same manufacturer or significant changes (hardware or software) to existing equipment shall undergo the same approval process as the original equipment unless it can be shown by analysis and tests acceptable to the Administrator that the new model will function as well or better than the approved equipment. A first-time approval is conducted in four phases:
(i) Lab/Bench Tests and Equipment Data Evaluation. This phase consists of the following:
(A) Analysis of the manufacturer’s procedures for development of software and review of supporting documentation in accordance with the guidelines of paragraph 9b(1) of this AC.
(B) Verification of compliance with the appropriate environmental qualification standards and tests specified in the individual sensor TSO’s and in RTCA/DO-160C.
(C) Verification of compliance with the applicable minimum performance and operation standards specified in TSO-C115b and other TSO’s applicable to the individual sensors incorporated in the system.
(D) Analysis of failure modes and annunciations.
(E) Review of reliability data to establish that all probable failures are detected and that failure rates meet acceptable criteria (e.g. as detailed in AC
25.1309-1A).
(F) Evaluation of the ease of use of the controls and of the viewing ease (e.g. brightness, contrast, intensity, dimming, etc.) of the displays and annunciations from a human factors point of view.
(G) Review of installation and maintenance manuals. Special attention should be given to the manufacturer’s instructions for locating all antennas on the aircraft. Refer to paragraph 9.c.(1)(ii)(G) of this AC for specific information that should be included in these instructions.
(H) Evaluation of the operator’s manual (pilot’s guide).
(ii) Aircraft Installation Data Evaluation. Normally the manufacturer of the multi-sensor equipment will provide an aircraft as a test bed for the first time installation approval. This approval may serve as a basis for subsequent installation approvals. The following assessments are to be made:
Par 9 27 (A) Review of installation drawings, wiring diagrams, and descriptive wiring routing.
(B) Evaluation of the cockpit layout of the installed equipment with emphasis on equipment controls, applicable circuit breakers (labels and accessibility), switching arrangement, and related indicators, displays, annunciators, etc.
(C) Analysis of a data flow diagram in order to review which equipment provides what data to which other equipment.
(D) Review of a structural analysis of the equipment installation, including antenna(e), in order to ascertain whether structural mounting, dynamic, and crash load requirements are satisfied.
(E) Review of an electrical load analysis in order to verify that the total electrical load requirements are within the capabilities of the aircraft’s electrical generating system. Determine that the supplied electrical power is consistent with applicable equipment reliability requirements.
(F) Verification that the aircraft environment in which the multi-sensor equipment is installed is appropriate to the environmental categories (or criteria) as identified in 9.c.(1)(i)(B) or the individual TSO to which the equipment has been tested.
(G) Evaluation of the antenna installation. A critical aspect of many multi-sensor equipment installations is the installation of the antenna(e). It is important that the antenna for each sensor is approved for the particular type (make and model) sensor installed.
(1) Adequate isolation must be provided between a GPS antenna and any other transmitting antenna(s) installed on the aircraft in order to prevent interference. Shadowing by aircraft structure can adversely affect the operation of GPS equipment. Typically, a GPS antenna is located forward of the wings on the top of the fuselage to minimize effects of the wings, tail, etc. during aircraft maneuvering. For installations on helicopters, the effects of the rotor blades on antenna performance must be considered.
NOTE: 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), and other transmitting antennas (particularly “L” band) should be carefully evaluated for potential mutual interference.
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(2) E-field antennas (whip, plate, or blade type) are typically used with Loran-C sensors and many Omega/VLF sensors. Precipitation static has an adverse effect upon the signal receiving capability of this type of antenna. The adverse effects of P-static can be minimized by use of the proper antenna type and location, by proper installation of high-quality static dischargers, and by proper bonding of airframe surfaces. The manufacturer’s installation or maintenance manual usually describes acceptable E-field antenna installation practices. Each aircraft should be subjected to a careful ohmic survey of electrical airframe bonding (an electrical bonding limit of 10 milliohms is considered acceptable). P- static protection is a required part of the system installation and must be maintained for proper system operation.
(3) H-field antennas (loop type) are typically used with Omega/VLF sensors. The signal receiving quality of this type of antenna is adversely affected by aircraft electrical skin currents, particularly by 400 Hz ac. P-static has no appreciable effect on an H-field antenna, and its effects are usually not observed. A procedure called skin mapping is normally employed to determine a good mounting location for H-field antennas. It should be noted that shifting major aircraft electrical components to different locations within the aircraft or installing new equipment subsequent to antenna installation may render a previously determined skin map location unsuitable. A simple test to verify the effectiveness of an H-field antenna installation located by skin mapping is to park the aircraft away from any external electrical noise source. Then, using only the aircraft’s battery, and with all other electrical equipment off, activate the multi-sensor equipment and record signalto-noise values (or quality factors) for all receivable stations of the appropriate sensor. Repeat this process of recording signal-to-noise values (or quality factors) with engine(s) running and all electrical/electronic equipment operating on aircraft power. If the antenna installation is satisfactory, there should not be any significant degradation in signal reception.
(iii) Ground Test Evaluations. For multi-sensor equipment incorporating a Class B() or C() GPS sensor, static ground tests are conducted to verify the installed GPS equipment configuration (including antenna) provides position data meeting the accuracy criteria specified in paragraph 7a(1) of this AC. These tests shall cover a continuous period of 24 hours with a maximum sample interval of five minutes.
NOTE: The 24-hour ground accuracy test may be performed on the aircraft or by use of a representative mock-up configuration. If a mock-up test fixture is used, the entire installed GPS equipment configuration, including antenna, must consist of the hardware to be used in the installation and be representative of the installed system configuration.
(iv) Flight Test Evaluations. Flight tests are conducted to verify proper operation and accuracy of the multi-sensor equipment as installed in the aircraft. Flight tests should include at least the following:
Par 9 29 NOTE 1: Required flight evaluation for any new sensor should be conducted according to the AC for installation of that sensor (Reference 4.d).
NOTE 2: Required flight evaluations for the first-time airworthiness approval of a particular multi-sensor equipment are accomplished by the cognizant Aircraft Certification Office unless specific tests are delegated by the ACO to a Flight Test Pilot Designated Engineering Representative (DER).
(A) Evaluation of all operating modes of the multi-sensor equipment. Particular attention should be given to mode switching and transition requirements associated with the approach mode for equipment incorporating Class B1, B3, C1, and C3 GPS sensors.
(B) Evaluation of the interface (function) of other equipment connected to the multi-sensor equipment.
(C) Review of various failure modes and associated annunciations, such as loss of electrical power, loss of signal reception, equipment failure, individual sensor failure, autopilot/flight director response to system flags, etc.
(D) Evaluation of steering response while autopilot and/or flight director is coupled to the multi-sensor equipment during a variety of different track and mode changes. This evaluation shall include, as applicable, transition from en route to approach transition to approach modes and vice-versa. Additionally, all available display sensitivities shall be evaluated.
(E) Evaluation of displayed multi-sensor equipment parameters on interfaced cockpit instruments such as HSI, CDI, distance display, electronic flight instruments system (EFIS), moving maps, fuel management systems, etc.
(F) Assessment of all switching and transfer functions, including electrical bus switching, pertaining to the multi-sensor equipment installation.
(G) Evaluation to determine satisfactory electromagnetic compatibility (EMC) between the multi-sensor equipment installation and other onboard equipment (this test may be partially accomplished as a ground test).
NOTE 1: For systems incorporating a GPS sensor, particular attention should be given to other “L” band equipment, such as TCAS or SATCOM equipment, VHF transmissions on the frequencies stated in paragraph 9b(6)(iii) of this AC, high frequency (HF)
30 Par 9 communications systems, and other transmitting equipment (ACARS, AFIS, Flightfone, etc.).
NOTE 2: Installation instructions for each GPS receiver installation shall include the requirement for verification of adequate isolation from the harmonic interference of VHF communication transceivers.
These tests shall be conducted on the completed GPS installation by tuning each VHF transmitter to the frequencies listed below and transmitting for a period of 20 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 (low pass or notch filters installed at the output of the VHF transmitter, additional spacing between the VHF transmitter and the GPS antenna, replacement of the VHF transmitter with a unit having no excessive harmonic emissions, etc.) be included in the aircraft installation. Reevaluation of installed VHF transceiver performance is not necessary if the filter insertion loss is 2 dB or less.
The following VHF frequencies shall be evaluated:
121.150 MHz 131.250 MHz
121.175 MHz 131.275 MHz
121.200 MHz 131.300 MHz Proper radio regulations (FCC Rules) must be observed.
NOTE 3: For Omega/VLF and Loran-C systems that incorporate an E-Field antenna, testing should be conducted in accordance with paragraph 9.b.(7).
(H) Evaluation of the accessibility of all controls pertaining to the multi-sensor equipment installation.
(I) Evaluation of the visibility of the controls, displays, and annunciators relating to the multi-sensor equipment installation during day and night lighting conditions. No distracting cockpit glare or reflections may be introduced, and all controls must be illuminated for identification and ease of use. Night lighting shall be consistent with other cockpit lighting.
(J) Analysis of crew workload when operating the multisensor equipment in association with other piloting requirements.
Par 9 31 (K) 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. Note that the accuracy associated with a GPS sensor must be demonstrated to enable potential operating benefits.
(1) GPS sensor accuracy should be verified in each operating mode by at least 5 low altitude over flights of one or more surveyed locations (ensure survey point coordinates are relative to WGS-84). An acceptable method of conducting this accuracy demonstration is to accomplish low altitude (less then 100 feet AGL) overflight of a runway threshold and record the GPS position as the aircraft crosses the threshold. The system accuracy is the distance between the coordinate position determined by the GPS and the coordinate position of the surveyed location (runway threshold). Runway threshold coordinates may be obtained from the airport operator. If coordinate data conversion to WGS-84/NAD-83 is necessary, contact the National Flight Data Center at (202) 267-9277.
(2) Initial certification for systems including an Omega/VLF sensor that has not previously been certified shall be based upon a demonstration of system accuracy by recording (at not less than 15 minute intervals) the Omega/VLF sensor position and comparing it to the actual position during evaluation flights representative of the area in which approval is desired. Suitable accuracy and navigation capability must be demonstrated using Omega only. VLF signals may be used to augment and expand areas of coverage, but the system must be demonstrated to be capable of meeting all navigation performance requirements using Omega signals only in an area of nominal Omega coverage.
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, aircraft movement, time of day, etc. The system should demonstrate its ability to re-acquire Omega/VLF signals after power interruptions of less than seven minutes and more than seven minutes, as well as in areas of marginal performance. It should demonstrate its ability to detect inadequate navigation capability, poor signal quality, etc.
(3) Initial certification for systems including a Loran- C sensor that has not previously been certified shall be based upon a demonstration of system accuracy by recording (at not less than 15 minute intervals) the Loran-C sensor position and comparing it to the actual position during evaluation flights representative of the area in which approval is desired. 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, chain/station selection criteria, known poor signal areas, aircraft movement, seasonal effects (i.e., snow pack vs. trees, water vs. ice, etc.), time of day,
32 Par 9 etc. The system should demonstrate its ability to detect poor signal conditions, inadequate navigation capability, operations outside approved operating areas, and the ability to reacquire the Loran-C signal following momentary signal interruptions and prolonged (more than 5 minutes) in-flight power failure, etc.
(4) Initial certification for systems including a VOR/DME or multiple (scanning) DME sensor that has not been previously certified shall 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. 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 VOR/DME auto-tune logic should be reviewed and tested to verify that all three types of VOR/DME ground stations are identified and tuned correctly.
(5) Initial certification for systems including an inertial navigation system (INS) or inertial reference unit (IRU) that has not been previously certified shall be based upon a demonstration of system accuracy by recording (at no greater than 15 minutes intervals) the INS/IRU sensor position and comparing it to the actual position during evaluation flights representative of the area in which approval is desired. Recorded data should include sufficient sensor performance parameters to provide a clear indication of satisfactory sensor performance and drift rates. The system should demonstrate its ability to detect inadequate navigation capability, operations outside approved operating areas, recovery from power failure, reinitialization in flight, alignment in limiting areas, etc. This demonstration should include 150 system flights at greater than 3 hours. At the end of the flight, the systems must exhibit less than 2.0 nmi drift rates. For systems that will be operated for more then 10 hours, the system must stay within 20 nmi x 25 nmi for the maximum deviation allowed (See AC 25-4).
(L) Verify continuity of navigation data during normal aircraft maneuvering, including holding patterns and turns at up to at least 30 degrees of bank for a 360 degree turn left and right.
(M) Verify that flight technical error (FTE) can be maintained at less than 1.0 nmi for en route, 1.0 nmi for terminal (approach transition), and
0.25 nmi (for equipment that is seeking credit for GPS data) or 0.5 nmi (for equipment not using or not seeking credit for GPS data) for approach operating modes, both with and without autopilot and/or flight director, as applicable.
(N) For equipment including an approach mode, conduct a sufficient number of approaches using the navigation data base to verify the proper operation of annunciations, waypoint sequencing, and display sensitivity changes, as appropriate, in
Par 9 33 accordance with the requirements specified in TSO-C115b and other TSO’s applicable to the specific sensors incorporated in the multi-sensor equipment. This evaluation should include at least: turn anticipation, waypoint sequencing, display sensitivity changes, annunciations, procedure turns at the final approach fix (FAF), holding patterns at the missed approach holding fix, transitions from TO-FROM operation to TO-TO operation, heading legs after the initial approach fix (IAF) to intercept the final approach course both before and after the FAF, and DIRECT TO operation before and after the IAF.
(2) Follow-On IFR Airworthiness Installation Approvals. This type of approval refers to installation approvals in any model or type of aircraft after a first time airworthiness approval of the particular multi-sensor equipment has been issued. Follow-on approvals may use the first time airworthiness approval, which was either a TC or an STC, as a basis for installation approval, if the flight standards inspector determines that there are no design changes as a result of the installation. The determination of a design change will be dependent upon the integration with other avionics and not on the basis of aircraft make and model. Since the GPS equipment operates on principles that are not dependent upon the aircraft make and model, the engineering evaluation of one aircraft model is applicable to a different aircraft provided the integration with the other equipment is equivalent.
(i) Unless otherwise provided, contact either the manufacturer or organization responsible for obtaining the first time airworthiness approval of the multi-sensor equipment in order to:
(A) Obtain a sample airplane or rotorcraft flight manual supplement (or supplemental flight manual, if appropriate).
(B) Obtain verification of the equipment approval status, including antenna, software, autopilot/flight director interface, and system integration requirements, etc.
(C) Discuss any problem areas and seek assistance in their solution.
(D) Verify that the maximum operating speed for which the multi-sensor equipment is qualified is compatible with the maximum expected ground speed of the aircraft.
(ii) If the aircraft is approved for flight in known icing conditions, verify the suitability of the antenna installation in accordance with the guidance specified in paragraph 9b(8) of this AC.
(iii) Conduct a similar data evaluation as outlined in paragraph 9c(1)(ii) of this AC.
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(iv) Conduct a functional flight evaluation covering at least the following items:
NOTE: Required flight evaluations will be conducted by the cognizant Aircraft Certification Office (ACO) or, when authorized, by a flight test pilot designated engineering representative (DER) in accordance with the procedures used by the cognizant ACO. Depending upon the level of similarity between the initial and follow-on installations, including aircraft type, the Flight Standards District Office (FSDO) Inspector may accept flight evaluations conducted by the installer.
(A) Overall operation of the installed multi-sensor equipment, including interface with other equipment in the aircraft.
(B) The effect(s) of multi-sensor equipment and sensor failure (open circuit breaker), including autopilot /flight director response, if applicable.
(C) If interfaced with an autopilot or flight director, steering response while the autopilot or flight director is coupled to the multi-sensor equipment.
(D) Displayed navigation parameters on all interfaced cockpit instruments.
(E) The effect(s), if any, of switching and transfer functions, including electrical bus switching, pertaining to the multi-sensor installation.
(F) Evaluation to determine satisfactory electromagnetic compatibility (EMC) between the multi-sensor equipment installation and other equipment as specified in paragraph 9c(1)(ii)(G) of this AC.
NOTE: Verification of adequate isolation from harmonic interference of VHF communication transceivers in each individual aircraft is required for installation of multi-sensor equipment using GPS. This test should be repeated if a VHF transceiver is replaced or added, or if a new or replacement VHF communications antenna is installed.
(G) Evaluation of the accessibility and visibility of all controls and displays pertaining to the multi-sensor equipment installation.
(H) Validate multi-sensor equipment navigational accuracy in each operating mode. Previously approved sensors need only be evaluated to the extent necessary to verify accuracy has not been degraded by the equipment installation in the particular aircraft.
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(1) GPS sensor accuracy is evaluated as specified in paragraph 9c(1)(iv)(K)(1) of this AC.
(2) Omega/VLF sensor accuracy is evaluated by conducting a short flight (approximately 100 nmi) and verifying position accuracy by overflight of at least 3 reference locations or comparison to a valid GPS, Loran-C, or DME/DME position.
(3) Loran-C sensor accuracy can be evaluated in the same manner as that specified for GPS sensors, except that five different locations should be used.
(4) VOR/DME and DME/DME sensor accuracy can be evaluated in the same manner as that specified for GPS sensors, except that five different locations should be used.
(5) INS/IRU sensor accuracy can be evaluated as an average drift over the entire flight (should be less than 2.0 nmi/hr.)
(I) Verify continuity of navigation data during normal aircraft maneuvering, including holding patterns and turns at up to at least 30 degrees of bank for left and right 360 degree turns.
(J) Monitor displayed cross-track error to verify that flight technical error (FTE) is less than 1.0 nmi for en route, 1.0 nmi for terminal (approach transition), and 0.25 nmi (for equipment using GPS data) or 0.5 nmi (for equipment not using GPS data) for approach operating modes, both with and without autopilot and/or flight director, as applicable.
(K) For equipment including an approach mode, conduct at least three published instrument approaches (retrieved from the database) to verify the proper operation of the equipment in the approach environment. This test should be conducted separately for each sensor, for which approach approval is sought. If multiple sensors are to be used, then all combinations should also be tested.
10. OPERATIONAL CONSIDERATIONS.
a. Flight Manual Supplement. An appropriate Airplane or Rotorcraft Flight Manual Supplement (or, for aircraft without an FAA Approved Flight Manual, a Supplemental Flight Manual) containing the limitations and operating procedures applicable to the equipment installed should be provided for each installation of multi-sensor equipment for IFR approval. A Flight Manual Supplement or Supplemental Flight Manual may be necessary for installations limited to VFR use only, depending upon the complexity of the installation and need to identify necessary limitations and operating procedures.
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b. Other Navigation Equipment Required. Aircraft employing multi-sensor equipment for IFR navigation must also be equipped with an approved and operational alternate means of navigation appropriate to the intended route to be flown. Within the contiguous United States, Alaska, Hawaii, and surrounding coastal waters, this requirement may be met with an operational, independent VOR receiver, although data from this receiver can provide an input to the multi-sensor equipment. For oceanic and remote operations, an alternate means of navigation is required unless the multi-sensor equipment incorporates within itself a sensor approved individually for the particular area of operations (some oceanic airspace may require additional redundancy).
c. Alternate Airport Requirements. An alternate airport (if required by the applicable operating rules) must be served by an approved instrument approach procedure based on a navigation system other than GPS or Loran-C and the aircraft must be properly equipped to conduct that approach.
d. Operational Area. Operators and their flight crews must consult the approved flight manual supplement for their aircraft to determine approved operational areas that may apply to particular systems and/or sensors. Flight crews must be aware that operational areas for different systems/sensors may be different, and the appropriate operating area(s) for a particular system can only be determined by reference to the approved flight manual supplement or other FAA approved documents.
JOHN K. McGRATH Manager, Aircraft Engineering Division