a. Equipment eligibility. ADS-B antennas must meet requirements defined in the ADS-B equipment manufacturer’s installation manual.
b. Installation guidance.
(1) Utilizing an existing antenna. When utilizing an existing antenna system, if the installation does not modify the existing antenna(s), cabling, or output specifications, the antenna installation does not have to be reevaluated.
(2) Installing a new shared transponder/ADS-B antenna. Follow the transponder antenna installation guidance in AC 20-151A.
(3) Installing a new stand-alone UAT ADS-B antenna. If the UAT system is installed in an aircraft without a transponder or the installation will not utilize the existing transponder antenna, use the following guidance:
(a) Antenna location. Mount antennas as near as practical to the centerline of the fuselage and locate them in a position to minimize obstruction in the horizontal plane.
(b) Antenna distance from other antennas. The spacing between the UAT antenna and any transponder (Mode S or Air Traffic Control Radar Beacon System (ATCRBS)) antenna must provide a minimum of 20dB of isolation between the two antennas. If both antennas are conventional omni-directional matched quarter-wave stubs, 20 dB of isolation is obtained by providing a spacing of at least 20 inches between the centers of the two antennas. If either antenna is other than a conventional stub, the minimum spacing must be determined such that 20 dB or more of isolation is achieved.
(c) Transmit power. Transmit power will be verified during ground test.
(d) Structural analysis. You must submit a structural analysis of new antenna installations to show compliance with the applicable regulations.
(4) Antenna diplexers. Diplexers manufactured in accordance with TSO-C154b or TSO-C154c may be installed so that UAT ADS-B equipment and a transponder may share the same antenna. The TSO-C154b and TSO-C154c diplexer installation instructions are required to have a limitation that ensures insertion of the diplexer does not exceed the maximum cable attenuation allowance between the transponder and antenna.
(5) Single antenna. Single antenna systems must utilize a bottom mounted antenna.
c. Configuration of associated parameters. The following paragraphs provide additional guidance on setting key ADS-B OUT parameters. Definitions for each of the following associated parameters are included in appendix 1.
(1) GNSS antenna offset and position offset applied (POA). Although not required to comply with 14 CFR 91.227, it is highly encouraged for ADS-B equipment manufacturers to
24 provide instructions to installers for setting this parameter and for installers to configure the offset during installation. The GNSS antenna offset information will be extremely valuable for surface ATC surveillance and future ADS-B IN surface situational awareness and surface collision alerting applications. If the ADS-B equipment is interfaced to multiple GNSS position sources that utilize GNSS antennas in different locations on the aircraft, the installation must have provisions to ensure the appropriate GNSS antenna offset is being transmitted when the ADS-B equipment switches from one position source to another.
(2) Single antenna bit. For aircraft using a single antenna, this parameter should be set to True.
d. Mutual suppression. Follow the ADS-B equipment manufacturer’s guidance on interfacing the ADS-B OUT equipment to the mutual suppression bus.
3-9. Vertical Rate Source. We recommend that the ADS-B system output the vertical rate field when available. The vertical rate may come from a barometric air data computer, a GNSS source, or a system which filters barometric and geometric vertical rates. Vertical rate will typically come from a position source or an air-data computer. This section addresses this unique parameter, and augments paragraph 3-3 and 3-4, as applicable.
a. Equipment eligibility. Unlike position accuracy, vertical velocity accuracy is not transmitted in ADS-B messages. Thus it is important that vertical velocity sources integrated into the ADS-B system meet minimum performance requirements at installation. Use the following guidance:
(1) Hybrid vertical rate source. Vertical rate may be taken from a hybrid system which filters barometric vertical rate with an Inertial Reference Unit (IRU) vertical rate and GNSS vertical rate, provided the hybrid system was tested and approved to provide a vertical rate output with an accuracy that is at least as good as barometric vertical rate sources (e.g., TSO-C106). Hybrid vertical rate could come from a Flight Management System (FMS), Air Data and Inertial Reference System (ADIRS), or an IRU. ADS-B equipment should transmit hybrid vertical rate solutions as barometric vertical rates.
(2) Blended vertical rate source. Vertical rate may be taken from a blended system which filters IRU vertical rate and barometric vertical rate, provided the blended system was tested and approved to provide a vertical rate output with an accuracy that is at least as good as barometric vertical rate sources (e.g., TSO-C106). Blended vertical rate could come from a FMS, ADIRS, or an IRU. ADS-B equipment should transmit blended vertical rate solutions as barometric vertical rates.
(3) Barometric vertical rate source. Barometric vertical rate may be taken from an air data computer meeting the minimum performance requirements of any revision of TSO-C106 or a vertical velocity instrument meeting the minimum performance requirements of applicable revisions of TSO-C8, Vertical Velocity Instruments. We recommend you use any revision of a TSO-C106 compliant air data computer if you interface barometric vertical rate to the ADS-B OUT equipment.
(4) GNSS vertical rate source. Geometric vertical rate may be taken from any revision of TSO-C129, TSO-C145, TSO-C146, or TSO-C196 GNSS equipment if the position source has been qualified to provide vertical rate in accordance with appendix 2. Do not interface GNSS vertical velocity if the equipment has not been qualified in accordance with appendix 2.
(5) Inertial vertical rate source. Vertical velocity from an inertial sensor that is not blended with barometric altitude should not be transmitted from the ADS-B system.
(6) Barometric altitude source. ADS-B systems should not derive a barometric altitude rate by sampling barometric altitude measurements. This could lead to misleading vertical velocity information. If barometric vertical rate is not available, use geometric vertical rate.
b. Installation guidance. The vertical rate field can be populated with either barometric vertical rate or geometric vertical rate. There is no requirement to interface multiple vertical velocity sources. We recommend that you use the following priority scheme when selecting or interfacing multiple vertical rate sources:
(1) Hybrid vertical rate or blended vertical rate.
(2) Barometric vertical rate.
(3) GNSS vertical rate.
c. Configuration of associated parameters. The following paragraphs provide additional guidance on setting key ADS-B OUT parameters.
(1) Vertical rate. Interface vertical rate from one or more of the sources listed above.
Ensure the source provides vertical rate in feet per minute, or ensure the ADS-B equipment can recognize the vertical rate basis and convert the vertical rate to feet per minute.
(2) Vertical rate source. The source bit for vertical rate should be coded as barometric when utilizing barometric rate from an air data computer, or when using a blended or hybrid vertical rate. The source bit for vertical rate should only be coded as geometric when using vertical rate from a GNSS source.
3-10. Air-Ground Considerations.
a. The length and width code is required by 14 CFR 91.227, and is only transmitted in the surface position message. Thus, to comply with the rule, the aircraft must automatically determine its air-ground status and transmit the surface position message, which includes the length and width code, when on the ground.
b. For aircraft with retractable landing gear, the air-ground status determination is typically provided through a landing gear weight-on-wheels switch. For aircraft that have fixed-gear, the
26 ADS-B system must still be able to determine the air-ground status of the aircraft. Installations that provide a means to automatically determine air-ground status based on inputs from other aircraft sensors may be acceptable if they can be demonstrated to accurately detect the status. For example, air-ground status may be derived from Weight-on-Wheels (WOW) switch and GPS velocity, OR GPS velocity, an airport database and geometric altitude, OR GPS velocity and airspeed. These algorithms should be tested and validated during the installation approval.
Note: 1: We recommend that any automatic air-ground determination be more robust than just a simple comparison of ground speed to a single threshold value. Field experience has shown that this method can lead to false air-ground status.
Note: 2: Manual selection of the air-ground status is not acceptable.
c. TSO-C112d, Air Traffic Control Radar Beacon System/Mode Select (ATCRBS/Mode S) Airborne Equipment, requires Mode S transponders to inhibit the reply to Mode A/C/S all-call and Mode S-only all-call interrogations on the surface. Mode S transponders with ADS-B functionality will now remain “ON” during surface operations, thus it is imperative that you ensure the transponder interface to the air-ground status is installed correctly and that the transponder does not reply to Mode A/C/S all-call or Mode S-only all-call interrogations on the surface.
Note: In deploying Airport Surface Detection Equipment version X (ASDE-X) at various airports we have found transponder installations that have been improperly wired and therefore inappropriately respond to ATC and TCAS interrogations while on the airport surface.
3-11. Foreign Airspace Requirements.
a. Optional Parameters. If operations are planned in a country that requires parameters not mandated in the US, such as selected heading and selected altitude, follow the ADS-B equipment manufacturer’s installation guidance to interface those parameters. The FAA will cooperate with foreign regulators to ensure compliance with their requirements.
27 Chapter 4. T est & Evaluation
4-1. Ground Test.
a. Systems interface testing. Verify that the installed ADS-B equipment meets its intended function and transmits the appropriate information from each of the interfaced systems (position source, barometric altitude source, heading source, TCAS II, pilot interface, etc).
Coordinate with local ATC before broadcasting over the air to prevent being a source of interference to ATC or ADS-B IN equipped aircraft in the area. For example, transmitting airborne position reports with simulated airborne altitudes while on the surface will produce false targets for the ATC surveillance systems or airborne ADS-B IN equipped aircraft.
b. System latency. Latency is addressed through analysis rather than testing. See paragraph 3-1.
c. Rule compliance. Ensure the ADS-B system meets the requirements of 14 CFR 91.227.
(1) Accuracy and Integrity Performance. Ensure the installed system meets its stated accuracy and integrity performance under expected operating conditions. We recommend that you accomplish a GNSS performance prediction for the applicable time of your test to ensure the ADS-B system meets the predicted performance. In absence of predicted GNSS performance, demonstrate that you meet all 14 CFR 91.227 (c)(1) requirements, listed in table 2.
Table 2. Accuracy and Integrity Requirements NIC ≥ 7 R c < 370.4 m (0.2 nm) NACP ≥ 8 EPU < 92.6 m (0.05 nm) NACV ≥ 1 < 10 m/s SIL ≥ 3 ≤ 1x10-7 per hour or sample SDA ≥ 2 ≤ 1x10-5 per hour
(2) Parameters. Ensure all 14 CFR 91.227(d) parameters are properly populated and transmitted.
(3) Position accuracy. Position the aircraft on a surveyed location and validate the position transmitted from the ADS-B system. Ensure that the position transmitted is within the allotted NACP accuracy limit. For example, if the aircraft reports a NACP = 8, the ADS-B position should be within
92.6 meters, 0.05 nm. If the aircraft reports a NACP = 10, the ADS-B position should be within 10 meters. Reference appendix 1 for a complete list of NACP values. If the transmitted position accuracy is smaller or equal to the resolution of the test equipment, it is acceptable to use plus or minus one Least Significant Bit as the pass/fail criteria.
(4) Barometric Altitude Accuracy. Validate that the barometric altitude transmitted from the ADS-B system is accurate to within 125 feet. If the aircraft has a transponder installed, you must also validate that the ADS-B barometric altitude matches the transponder barometric altitude.
d. Electromagnetic Interface (EMI)/Electro Magnetic Compatibility (EMC) testing.
Provide an EMI/EMC test plan that demonstrates compliance with 14 CFR 23.1431 (a) and (b), 14 CFR 25.1353 (a) and (b), 14 CFR 25.1431 (a) and (c), 14 CFR 27.1301, 14 CFR 27.1309, 14 CFR 29.1353 (a) and (b), 14 CFR 29.1431 (a) and (b) as appropriate. Accomplish EMI/EMC testing to ensure that the ADS-B equipment does not provide an interference source on other installed systems on the aircraft. Additionally, ensure that equipment already installed in the aircraft does not interfere with the ADS-B system. If the STC or TC only involves a software change to an existing approved Mode S transponder installation, and the software update will not affect the systems response to EMI, you do not need to accomplish EMI testing again.
e. Human machine interface. Evaluate the flight crew interface for the ADS-B OUT system including the human-system interface and system behavior. The ADS-B OUT system must be compatible with the overall flight deck design characteristics (such as access to controls, sunlight readability, night lighting, etc.) as well as the airplane environment, such as vibrations.
(1) Information display. Evaluate the ADS-B OUT system to ensure displayed information is easily and clearly discernible, and has enough luminance, size, and visual contrast for the pilot to see and interpret it. Ensure the pilots have a clear, unobstructed, and undistorted view of the displayed information. Ensure information elements are distinct and permit the pilots to determine the source of the information elements if necessary, when there are multiple sources of the same kind of information.
(2) Controls and labeling. Evaluate the controls for the pilot interface to ensure they are plainly marked as to their intended function, provide convenient operation, and prevent confusion and inadvertent operation of both the ADS-B system, and the other systems with which they interact.
Evaluate the acronyms, labels, and annunciations to ensure they are used consistently in the flight deck, and do not cause confusion or errors. If a control performs more than one function, evaluate the labels to ensure the labels include all intended functions, unless the function of the control is obvious.
During evaluation, consider line select keys, touch screens or cursor controlled devices (e.g., trackballs) as these can be susceptible to unintended mode selection resulting from their location in the flight deck (e.g., proximity to a foot rest or adjacent to a temporary stowage area).
(3) Annunciations and alerts. Evaluate all ADS-B annunciations and alerts to ensure they are clear and unambiguous, and provide attention-getting and saliency appropriate to the type of alert.
Compliance with AC 25-1322-1, AC 27.1322, and AC 29.1322 should be considered when evaluating ADS-B annunciations and alerts. The colors yellow/amber and red should be restricted to cautions and warnings, respectively. Evaluate the annunciations and indications to ensure they are operationally relevant and limited to minimize the adverse effects on flight crew workload. When an annunciation is provided for the status or mode of a system, it is recommended that the annunciation indicate the actual state of the system, and not just the position of a switch.
(4) Pilot interface errors. Installations not providing a single point of entry for the ADS-B and transponder for the Mode 3/A code, IDENT, and emergency status must accomplish an evaluation of the pilot interface controls to determine that they are designed to minimize entry errors by the flight
29 crew, and enable the flight crew to detect and correct errors that do occur. System interface design must also be evaluated to ensure that dual entry of the Mode 3/A code, IDENT, and emergency status does not introduce significant additional workload, particularly when communicating an aircraft emergency. Evaluations should consider pilot-detected and undetected error rates, pilot workload, as well as training times. See paragraph 3-7c(5) for additional information on transponder and ADS-B system single point of entry.
(5) Lighting. Evaluate all foreseeable conditions relative to lighting, including failure modes such as lighting and power system failure, and day and night operations.
f. Transponder regression testing. At a minimum, use the procedures outlined in AC 43-6(), Altitude Reporting Equipment and Transponder System Maintenance and Inspection Practices, to validate that the transponder is operating normally following the ADS-B installation. Use the procedures outlined in AC 20-151() for ADS-B systems that include installation of a new or modified Mode S transponder. If you are installing a new air-ground status capability for the ADS-B system and this functionality is also interfaced to the transponder, you must ensure that replies to the Mode A/C and ATCRBS / Mode S all-call interrogations are inhibited on the ground.
g. ICAO 24-bit address. For U.S. civil aircraft, demonstrate that the 24-bit address transmitted by the system correlates to the aircraft registration number. If the system has a separate Mode S transponder and UAT ADS-B system installed, then ensure both the transponder and ADS-B system both transmit the same correct ICAO 24-bit address. For non- U.S. registered aircraft, verify that the ICAO 24-bit address is the address assigned to the aircraft by the responsible State authority.
h. Self test. Evaluate the ADS-B self-test features (if provided) and failure mode annunciations to ensure that the pilot is able to determine whether the system is functioning properly.
i. Position source failure. Demonstrate that a failure or loss of the position source results in an indication to the operator of an ADS-B function failure. If a secondary position source is interfaced to the ADS-B equipment, ensure it meets all guidance in this AC. If the change from the primary position source to the secondary position source requires a change in SIL or SDA, ensure these changes are accomplished within 10 seconds.
j. Air-ground status. Verify that the air-ground inputs (or algorithms) are functioning properly and that the ADS-B system transmits the appropriate airborne messages or surface messages based on the air-ground status. This can be accomplished with simulated inputs to the appropriate sensors or accomplished in conjunction with the flight test. Rotorcraft may consider hover taxi as in the air
k. Transmit power. Transmit power testing must be accomplished if a new antenna has been installed, an existing antenna has been relocated, if a diplexer has been installed into an existing antenna system, or the output specifications on the transponder have changed. Perform the following testing to validate transmit power:
30 Note: Upgrading a previously installed and approved TSO-C112() Mode S transponder to include ADS-B functionality does not require transmit power testing unless a new antenna has been installed, the antenna location has changed, or the output specifications on the transponder have changed.
(1) 1090ES transmitter. Verify that the peak pulse power at the antenna end of the transmission line meets the minimum and maximum power levels summarized in table 3, considering the test equipment antenna gain and path loss. Repeat the measurement in each quadrant of the antenna pattern (forward, aft, left, right).
Table 3. Minimum and Maximum Transmitted Power from TSO-C166b
Tested Transmitter Class Minimum Power Maximum Power A1 21.0 dBW 27.0 dBW A1S 21.0 dBW 27.0 dBW B1 21.0 dBW 27.0 dBW B1S 21.0 dBW 27.0 dBW A2 21.0 dBW 27.0 dBW A3 23.0 dBW 27.0 dBW
(2) UAT transmitter. Verify that the peak pulse power at the antenna end of the transmission line meets the minimum and maximum power levels summarized in table 4, considering the test equipment antenna gain and path loss. Repeat the measurement in each quadrant of the antenna pattern (forward, aft, left, right).
Table 4. Minimum and Maximum Transmitted Power from TSO-C154c
Tested Transmitter Class Minimum Power Maximum Power A1H 12.0 dBW 16.0 dBW A1S 12.0 dBW 16.0 dBW B1 12.0 dBW 16.0 dBW B1S 12.0 dBW 16.0 dBW A2 12.0 dBW 16.0 dBW A3 20.0 dBW 24.0 dBW
l. TCAS. If a TCAS II system is installed on the aircraft, ensure that the proper messages are transmitted by the ADS-B system when the TCAS II is on and operating in a mode that can provide RAs. No TCAS II system regression testing beyond the ground interface testing covered in this section is required.
m. Transponder all-call inhibit. When ADS-B functionality resides in a Mode S transponder, conduct a test which demonstrates that replies to Mode A/C/S all-call and Mode S-only all-call interrogations are inhibited on the ground. Also demonstrate that replies to discrete interrogations are not inhibited.
n. Mode 3/A code and emergency code. Demonstrate that the correct Mode 3/A code and IDENT is transmitted. Do not transmit the 7500, 7600, or 7700 emergency codes over the air during ground or flight testing. If testing emergency codes is desired, contact the local ATC facility and coordinate testing to prevent a nuisance emergency response.
4-2. Flight Test.
a. Mutual interference. During all phases of flight, demonstrate that there is no mutual interference with any other aircraft system. Have all installed systems operating during the flight test.
b. Other system performance. Demonstrate the proper performance of any previously installed aircraft system(s) that required changes as a result of the ADS-B installation in accordance with the applicable policy. This can be accomplished with standard regression test procedures for the other installed system, and does not require a unique test for ADS-B.
c. User interface. Exercise all user inputs. If separate user inputs are required for the transponder and ADS-B systems, evaluate the flight manual procedures for ensuring that the same Mode 3/A code, IDENT, and emergency codes are transmitted from both systems.
4-3. In-Flight Test with FAA Ground System. Perform a flight test to show that the installed system performs properly with the FAA ground system. The test will verify that the FAA ground system properly receives the aircraft’s ADS-B broadcast messages, there are no drop outs and the information transmitted is complete and correct. Currently the only method available to accomplish the flight test is to fly within ADS-B service coverage and accomplish a post flight analysis of the data received from the FAA. This test is intended to evaluate the design interface for the position source and the ADS-B equipment. If you have flight test data from a previous STC or TC which established this compatibility, you do not need to re-accomplish the flight test.
Note: 1: This flight test is intended to complete a design approval under an STC or TC application; it is not intended for the alteration of individual aircraft.
Note: 2: Follow your standard process for requesting flight test authorization, there are no unique flight test authorization requirements for ADS-B flight tests.
a. Preflight coordination.
(1) Data retrieval. At least 48 hours prior to the flight, notify the FAA by e-mailing 9-avs-air-130flttest@FAA.gov that you require data from the flight test to support post flight analysis. Include contact information for your ACO point of contact, aircraft registration number or applicable call sign, 24-bit address, expected date, location and approximate time of the flight.
(2) ATC coordination. There is no ADS-B specific requirement to coordinate the flight test in advance with ATC. Follow normal flight test procedures for coordinating with ATC.
b. Flight test profile. This profile is intended to be flown on all ADS-B system approvals.
The profile need not be flown exactly, and variances for ATC clearances and vectors are acceptable. The flight test should be at least 1 hour long. If the profile is completed in less than 1 hour, continue the flight until enough data is collected. The flight test may not be performed using the random UAT 24-bit address feature, since the 24-bit address is a key field in retrieving the ATC flight profile data. The profile discussed in paragraph 4-3b(3) thru (7) below may be flown in any order.
(1) Location of flight. The flight may be accomplished in any airspace that has FAA ADS-B ground station coverage. See the following web site for information on existing ADS-B coverage in the National Air Space (NAS):
http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/enroute/surveillance _broadcast/coverage/
(2) Distance from ground station. This flight profile does not specify the distance the aircraft must be from an ADS-B ground station. Transmit power is evaluated through ground testing instead of demonstrating a minimum air-to-ground reception distance.
(3) Altitude. Fly the aircraft at multiple altitudes throughout the flight within ADS-B coverage. There is no maximum or minimum altitude required for the flight test.
(4) Turns. Verify the ADS-B system performs properly during turning maneuvers.
During the flight, place the aircraft in various normal configurations such as takeoff, approach, landing, and cruise configuration if appropriate for the airframe. During the flight, perform at least two left and two right 360-degree turns. Table 5 provides suggested altitude, speed and bank angle at which these turns should be made. The intent of this test is to ensure the ADS-B system operates properly over the normal flight regimes of the aircraft under test. Variations on altitude, speed and bank angle are acceptable as long as the intent of the test is met.
Table 5. Turns
Part 23 Aircraft Configuration Altitude Range AGL Speed Range Bank Angle Takeoff 3000-5000 1.4 V S 30 0 Approach or Landing 2000-7000 1.4 V S 30 0 Cruise 7000-10000 1.5 V S to 1.8 VS 300 Part 25 Aircraft Configuration Altitude Range Speed Range Bank Angle Takeoff 3000-5000 V 2 + 20 kts 30 0 Approach or Landing 2000-7000 V APP + 20 kts 30 0 Cruise 7000-10000 1.5 V S to 1.8 VS 30 0 Part 27 Rotorcraft Configuration Altitude Range Speed Range Bank Angle Landing 1000-3000 V Y + 10 kts 30 0 Cruise 2000-5000 0.8 V NE or 0.8 VH 300 Part 29 Rotorcraft Configuration Altitude Range Speed Range Bank Angle Landing 1000-3000 V Y + 10 kts 30 0 Cruise 2000-10000 0.8 V NE or 0.8 VH 30 0
(5) Climbs/descents. Verify the ADS-B system performs properly during climbs and descents. Table 6 provides a suggested rate at which climbs should be made during the test flight. Table 7 provides a suggested rate at which descents should be made during the test flight.
Climbs and descents should be at least one minute in length. The intent of this test is to ensure the ADS-B system operates properly over the flight regime of the aircraft under test. Variations on climb and descent rates are acceptable as long as the intent of the test is met.
.
Table 6. Climb Speeds
Configuration Part 23 Aircraft Part 25 Aircraft Part 27 Rotorcraft Part 29 Rotorcraft Take off V Y V FE - 10 kts V Y VY Cruise V Y V MO - 10 kts 0.8 V NE or 0.8 VH 0.8 VNE or 0.8 VH
Table 7. Decent Speeds
Configuration Part 23 Aircraft Part 25 Aircraft Part 27 Rotorcraft Part 29 Rotorcraft Cruise V NE-10 V MO - 10 kts 0.8 V NE or 0.8 VH 0.8 VNE or 0.8 VH Approach V FE-10 V FE - 10 kts V Y + 10 kts VY + 10 kts Landing V FE-10 V FE - 10 kts N/A N/A
(6) Position accuracy. Utilizing a known waypoint, fly a north/south course that crosses the defined waypoint followed by an east/west course that crosses the same defined way point.
c. Post-flight data retrieval. Within 48 hours of completing the STC or TC flight test against the FAA ground stations, email: amc-ajw-sbsm@faa.gov, to request flight data from your flight. You must include your Type Inspection Authorization, name and email address of your ACO project engineer, aircraft registration number or applicable call sign, 24-bit address, date, location and time of the flight.
d. Post-flight data analysis. You must accomplish a post flight data analysis to ensure that the aircraft is transmitting accurate ADS-B information. Ensure all data associated with the track is consistent, such as position, 24-bit address, velocity, flight ID, barometric altitude, Mode 3/A code, emitter category, and geometric altitude. The post flight data analysis should also reveal if there were any unexpected data dropouts that might be caused from intermittent wiring interfaces or interface incompatibility. The flight test does not require the use of a truth source to accomplish post flight data analysis, however the FAA will provide radar data when available to help analyze the flight track.
At a minimum, analyze the following areas:
(1) Rule compliance. Review the data from the FAA ground system for the flight to ensure the installed system meets its stated accuracy and integrity performance under flight conditions.
We recommend that you accomplish a GNSS performance prediction for the applicable time of your test and ensure the ADS-B system meets the predicted performance. Due to the design of existing GNSS receivers and typical GPS constellation configurations, there will be time periods where unaugmented GNSS solutions drop below the NIC and NACp performance required by the rule.
Such outages usually do not occur for more than 20 minutes and many are of much shorter durations.
If the integrity and accuracy of an existing GNSS installation does not meet the rule requirements during the test flight, the applicant should show that poor performance was caused by the constellation during the period of time that the flight occurred. If that cannot be established as the cause of the poor performance, then there may be a problem with the position sensor installation that needs to be investigated and resolved. Resolution of this type of issue will probably require the involvement of the position source manufacturer. There may also be short periods where position messages transmit NIC=0, velocity messages transmit NACv=0, and status messages transmit NACp=0, SIL=0. These can be caused by antenna shadowing and switching effects, and do not indicate an installation problem if they are infrequent and of short duration. All such outages must be less than 5 seconds in duration to avoid operational impacts. This condition may not occur more often than once every 1000 position transmissions when averaging all outages over the flight duration. If this condition occurs more often during the flight test, then the applicant must establish root cause and provide a solution prior to granting installation approval. Demonstrate that you meet all 14 CFR 91.227 (c)(1) requirements, listed in table 8, accuracy and integrity requirements during flight.
Table 8. Accuracy and Integrity Requirements During Flight
Ensure NIC ≥ 7 throughout the flight. R c <370.4 m (0.2 nm) Ensure NACP ≥ 8 throughout the flight. EPU <92.6 m (0.05 nm) Ensure NACV ≥ 1 throughout the flight. < 10 m/s Ensure SIL ≥ 3 throughout the flight ≤1x10 7 Ensure SDA ≥ 2 throughout the flight ≤1x10-5 .