19 Mode S Transponders, as applicable. No ADS-B interface is available or required for TCAS I systems.
Note: Many aircraft will be equipped with a Mode S transponder with ADS- B functionality and a TCAS II. The Mode S transponder is considered to be a component of the TCAS II system and also a component of the ADS-B system.
b. Installation guidance.
(1) TCAS II interface. TCAS II is not a required part of the ADS-B system, however if TCAS II is installed on your aircraft, the equipment must be integrated so that the “TCAS installed and operational” and the “TCAS traffic status” parameters indicate the real-time status of the TCAS II.
(2) TCAS II hybrid surveillance. If an ADS-B IN system is installed in an aircraft equipped with a TCAS II hybrid surveillance system compliant with RTCA/DO-300, Minimum Operational Performance Standards (MOPS) for Traffic Alert and Collision Avoidance System II (TCAS II) Hybrid Surveillance, the TCAS II will utilize ADS-B IN position data to reduce the interrogation rates of low threat intruders. The information transmitted by ADS-B OUT systems installed in accordance with the guidance in this AC is suitable for use by TCAS II hybrid surveillance. See AC 20-151A for more information on hybrid surveillance.
(3) The ADS-B transmission of the “TCAS operational” or “TCAS Resolution Advisory (RA) active” messages does not increase the hazard level of the ADS-B equipment defined in TSO-C166b or TSO-C154c.
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) TCAS installed and operational. This parameter must interface with the TCAS II system if a TCAS II system is installed on your aircraft. This parameter should be preset to ZERO if a TCAS II is not installed in your aircraft or if a TCAS I is installed in your aircraft.
Typically, this parameter will already be provided to the Mode S transponder from the TCAS II.
TCAS II systems compliant with TSO-C119() indicate they are operational and able to issue an RA when they transmit Reply Information (RI) = 3 or 4 to the transponder.
(2) TCAS traffic status. This parameter must be interfaced with the TCAS II system if a TCAS II system is installed on your aircraft. The TCAS traffic status parameter can be preset to ZERO in accordance with the ADS-B equipment manufacturer’s instructions if a TCAS II is not installed.
3-7. Pilot Interface.
a. Equipment eligibility. There are no unique equipment requirements.
b. Installation guidance.
(1) System status. The installation must have a method to display system operational status to the flight crew, which is consistent with the overall flight deck design philosophy. The system must display flight crew inputs such as Mode 3/A code, emergency codes, IDENT, and call sign. If an existing transponder is used to input Mode 3/A codes, emergency codes, and IDENT into the ADS-B system, the current transponder control interface is sufficient. The following two failure annunciations must be available to the flight crew.
(a) ADS-B device failure. If the ADS-B equipment is unable to transmit ADS-B messages, the system provides an appropriate annunciation to the flight crew.
(b) ADS-B function failure. The ADS-B system depends on a position source to provide the data to populate the ADS-B messages and reports. If the position source or its interface with the ADS-B equipment fails then the ADS-B system will not be able to broadcast the required ADS-B data. In this case, the ADS-B equipment has not failed but it cannot perform its function due to a failure to receive the position source data. TSO-C166b and TSO-C154c require this condition to be annunciated. The ADS-B system should distinguish between a position source or interface failure and an ADS-B equipment failure. The installer must provide documentation, in either an AFM or Pilot’s Guide, which explains how to differentiate between annunciation of an equipment failure and a function failure if the failure annunciations are not independent. The ADS-B function failure must not cause a TCAS II system failure.
(2) Turning off ADS-B. 14 CFR 91.225 requires that all aircraft equipped with ADS-B OUT operate with the equipment turned on at all times. There are no requirements to disable ADS-B broadcasts at the request of ATC. When ADS-B functionality resides in the Mode S transponder, it is acceptable to disable the ADS-B transmissions by disabling the transponder (i.e. Standby or Off). If this architecture is used, specify the impact in the flight manual or pilot’s guide, (e.g., loss of ADS-B, transponder and TCAS functionality).
Locate the ADS-B on/off controls to prevent inadvertent actuation.
(3) Anonymity feature. 14 CFR 91.227 contains specific provisions allowing operators with TSO-C154c equipment to transmit a self-assigned (randomized) temporary 24-bit address and no call sign. No such provision is provided for TSO-C166b equipment. After January 1, 2020 and in the airspace identified in 14 CFR 91.225, the UAT anonymous 24-bit address feature may only be used when the operator has not filed a flight plan and is not requesting ATC services. The UAT call sign may also be omitted, but only when the anonymous 24-bit address is chosen. We do not recommend integrating the anonymity features, as the operator will not be eligible to receive ATC services, may not be able to benefit from enhanced ADS-B search and rescue capabilities, and may impact ADS-B IN situational awareness benefits.
The following considerations must be included in the ADS-B system design when installing equipment capable of utilizing the anonymity feature:
(a) When the ADS-B equipment is initially powered-on, the 24-bit address must default to the aircraft’s assigned ICAO 24-bit address.
(b) When the ADS-B equipment is initially powered-on, the call sign may not be blank (Not Available per DO-282()). At initial power-on it is acceptable for the call sign to revert to a non-blank call sign which existed prior to the ADS-B equipment being powered off, or to the aircraft registration number.
(c) The ADS-B equipment can only allow an anonymous 24-bit address selection if the Mode 3/A code is set to 1200.
(d) The ADS-B equipment may only allow selection of the anonymous 24-bit address via a dedicated pilot interface. The ADS-B OUT equipment may not automatically set an anonymous 24-bit address or set a blank (Not Available per DO-282()) call sign based solely on pilot selection of the 1200 Mode 3/A code.
(e) The ADS-B OUT equipment must automatically disable the anonymity feature if any Mode 3/A code other than 1200 is selected. The 24-bit address must automatically revert to the aircraft’s assigned ICAO 24-bit address. If the call sign was blank, the call sign must automatically revert to the aircraft registration number.
(f) Describe the ramifications of selecting the anonymity features in the flight manual or Pilot’s Guide. Ramifications include the inability to receive Instrument Flight Rule (IFR) or Visual Flight Rule (VFR) separation services, potential loss of enhanced search and rescue benefits, and potential negative impacts to ADS-B IN applications.
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) Call sign/flight ID. The assigned aircraft registration number must be set as the call sign/flight ID during installation. Procedures for dynamically selecting a call sign must be included in the flight manual or pilot’s guide if the ADS-B equipment provides a means to input a radio telephony call sign. If pilot-selectable, the call sign/flight ID should be readily apparent to the flight crew. When the ADS-B equipment is initially powered on, the call sign/flight ID must be filled. At initial power-on it is acceptable for the call sign/flight ID to revert to a previously set call sign which existed prior to the ADS-B equipment being powered off, or to the aircraft registration number. See paragraph 3-7b(3) for information on use of the anonymity feature.
Note: The preset call sign/flight ID will have to be updated if the aircraft’s registration number changes.
(2) Emergency status. The installation must provide a means for the pilot to enter the emergency status of the aircraft. Although TSO-C166b and TSO-C154c identify multiple emergency codes, only the codes for general emergency, no communications, and unlawful interference are required to be available for broadcast. It is acceptable to base the ADS-B
22 emergency status on the emergency status code input into the transponder (i.e. Mode 3/A codes 7500, 7600, and 7700). See paragraph 3-7c(5) for information on single point of entry of the emergency status.
(3) IDENT. The installation must provide a means for the pilot to enter the IDENT feature. See paragraph 3-7c(5) for information on single point of entry of the IDENT.
(4) Mode 3/A code. The installation must provide a means for the pilot to enter the Mode 3/A code. See paragraph 3-7c(5) for information on single point of entry of the Mode 3/A code.
(5) Single point of entry. Aircraft equipped with a transponder and ADS-B system should provide the pilot a single point of entry into both systems for the Mode 3/A code, IDENT, and emergency status. If ADS-B equipment sets the emergency status, IDENT, or Mode 3/A code based on entry of these parameters into a separate transponder, the STC/TC needs to identify the appropriate transponder interfaces. Experience in the CAPSTONE program demonstrated that operator mitigations to prevent differing codes from being entered in the transponder and ADS-B system were ineffective and resulted in numerous false and misleading proximity alerts for ATC.
Additionally, there are workload and safety concerns of requiring the pilot to enter the Mode 3/A code, IDENT, and emergency codes multiple times. Thus, if you do not provide a single point of entry for the mode 3/A code, IDENT, and emergency code you must accomplish a human factors evaluation and an additional system safety assessment as follows:
(a) Human factors evaluation. Installations not providing a single point of entry must accomplish an evaluation of the pilot interface controls to ensure the design minimizes the potential for entry errors by the flight crew, and enables the flight crew to detect and correct errors that do occur. Evaluate the system interface design to ensure that dual entry of the emergency status, IDENT, and Mode 3/A code does not introduce significant additional workload, particularly when communicating an aircraft emergency. See paragraph 4-1e(4) for additional information on the human factors evaluation.
(b) System safety assessment. Transmission of false or misleading information is considered to be a major failure effect and may not occur at a rate greater than 1x10-5 per flight hour for ADS-B systems. Installations not providing a single point of entry must accomplish a safety assessment that demonstrates that the probability of the transponder and ADS-B system ever transmitting differing Mode 3/A codes is less than 1x10-5 per flight hour. The analysis must consider the potential of all pilot errors.
3-8. ADS-B Antenna Interface. The aircraft ADS-B antenna is an important part of the overall ADS-B OUT system because antenna systems are major contributors to the system link performance. The location and number of antennas required for the airborne ADS-B OUT system is a function of the equipment class of the selected broadcast link (UAT or 1090ES).
Single bottom-mounted antenna (TSO-C166b and TSO-C154c A1S and B1S classes) installations are allowed. For the UAT link, 16-watts minimum transmit power at the antenna output is required. For the 1090ES link, 125 watts minimum transmit power at the antenna output is required.
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.