32 system meet minimum performance requirements at installation. Use the following guidance:
3.9.1.1 Hybrid Vertical Rate Source.
Vertical rate may be taken from a hybrid system that 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 (such as TSO-C106). Hybrid vertical rate could come from a Flight Management System (FMS), Air Data and Inertial Reference System (ADIRS), or IRU. ADS-B equipment should transmit hybrid vertical rate solutions as barometric vertical rates.
3.9.1.2 Blended Vertical Rate Source.
Vertical rate may be taken from a blended system that 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 (such as TSO-C106).
Blended vertical rate could come from an FMS, ADIRS, or IRU. ADS-B equipment should transmit blended vertical rate solutions as barometric vertical rates.
3.9.1.3 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 (Rate-of-Climb). 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.
3.9.1.4 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
4.5.6Appendix B of this AC. Do not interface GNSS vertical velocity if the equipment has not been qualified in accordance with
4.5.6Appendix B.
3.9.1.5 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.
3.9.1.6 Barometric Altitude Source.
ADS-B systems should not derive a barometric altitude rate by sampling barometric altitude measurements. This could lead to misleading vertical
33 velocity information. If barometric vertical rate is not available, use geometric vertical rate.
3.9.2 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.
3.9.3 Configuration of Associated Parameters.
This section provides additional guidance on setting key ADS-B OUT parameters:
3.9.3.1 Vertical Rate.
Interface vertical rate from one or more of the sources listed in section
3.9.1 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.
3.9.3.2 Vertical Rate Source.
The source bit for vertical rate should be coded as barometric when using 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.
3.10.1 Length and Width Code.
The length and width code is required by § 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.
3.10.2 Air-Ground Status.
For aircraft with retractable landing gear, the air-ground status determination is typically provided through a landing gear weight-on-wheels (WOW) switch. For aircraft that have fixed gear, the 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 WOW switch and GPS velocity; or GPS
34 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.
Note 3: Rotorcraft may require unique logic for providing an accurate air-ground state.
A reliable method to determine the air-ground state should consider training requirements. Rotorcraft may consider hover taxi as in the air.
3.10.3 Mode S Transponder Inhibit.
TSO-C112d and TSO-C112e, 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 airground 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.
3.11.1 Optional Parameters.
If operations are planned in a country that requires parameters not mandated in the United States, such as selected heading and selected altitude, follow the ADS-B equipment manufacturer’s installation guidance to interface those parameters.
35 CHAPTER 4. TEST AND EVALUATION
4.1 Ground Test.
4.1.1 Systems Interface Testing.
Verify the installed ADS-B equipment meets its intended function and transmits the appropriate information from each of the interfaced systems (including the 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.
4.1.2 System Latency.
Latency is addressed through analysis rather than testing. Refer to section 3.1.3 and
4.5.6Appendix C of this AC.
4.1.3 Rule Compliance.
Ensure the ADS-B system meets the requirements of § 91.227.
4.1.3.1 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 § 91.227(c)(1) requirements as listed in Table 2.
Table 2. Accuracy and Integrity Requirements NIC ≥ 7 Rc < 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 per sample SDA ≥ 2 ≤ 1x10-5 per-hour
4.1.3.2 Parameters.
Per § 91.227(d), ensure the following parameters are properly populated and transmitted.
4.1.3.2.1 The length and width of the aircraft;
4.1.3.2.2 An indication of the aircraft's latitude and longitude;
4.1.3.2.3 An indication of the aircraft's barometric pressure altitude;
4.1.3.2.4 An indication of the aircraft's velocity;
4.1.3.2.5 An indication if TCAS II or ACAS is installed and operating in a mode that can generate resolution advisory alerts;
4.1.3.2.6 If an operable TCAS II or ACAS is installed, an indication if a resolution advisory is in effect;
4.1.3.2.7 An indication of the Mode 3/A transponder code specified by ATC;
4.1.3.2.8 An indication of the aircraft's call sign that is submitted on the flight plan, or the aircraft's registration number, except when the pilot has not filed a flight plan, has not requested ATC services, and is using a TSO-C154c self-assigned temporary 24-bit address;
4.1.3.2.9 An indication if the flightcrew has identified an emergency, radio communication failure, or unlawful interference;
4.1.3.2.10 An indication of the aircraft's “IDENT” to ATC;
4.1.3.2.11 An indication of the aircraft assigned ICAO 24-bit address, except when the pilot has not filed a flight plan, has not requested ATC services, and is using a TSO-C154c self-assigned temporary 24-bit address;
4.1.3.2.12 An indication of the aircraft's emitter category;
4.1.3.2.13 An indication of whether an ADS-B In capability is installed;
4.1.3.2.14 An indication of the aircraft's geometric altitude;
4.1.3.2.15 An indication of the Navigation Accuracy Category for Position (NACP);
4.1.3.2.16 An indication of the Navigation Accuracy Category for Velocity (NACV);
4.1.3.2.17 An indication of the Navigation Integrity Category (NIC);
4.1.3.2.18 An indication of the System Design Assurance (SDA); and
4.1.3.2.19 An indication of the Source Integrity Level (SIL).
4.1.3.3 Position Accuracy.
Position the aircraft on a surveyed location and validate the position transmitted from the ADS-B system. Ensure 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. Refer to 4.5.6Appendix A of this AC 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.
4.1.3.4 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.
4.1.4 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), 25.1353(a) and (b), 25.1431(a) and (c), 27.1301, 27.1309, 29.1353(a) and (b), and 29.1431(a) and (b) as appropriate. Accomplish EMI/EMC testing to ensure the ADS-B equipment does not provide an interference source on other installed systems on the aircraft. Additionally, ensure 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.
4.1.5 Human Machine Interface.
Evaluate the flightcrew 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 flightdeck design characteristics (such as access to controls, sunlight readability, night lighting, etc.) as well as the aircraft environment (such as vibrations).
4.1.5.1 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 pilots to see and interpret it. Ensure the pilots have a clear, unobstructed, and undistorted view of the displayed information elements.
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.
4.1.5.2 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 flightdeck, 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 (such as trackballs) as these can be susceptible to unintended mode selection resulting from their location in the flightdeck (for example, proximity to a footrest or temporary stowage area).
4.1.5.3 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, Flightcrew Alerting;
AC 27.1322 (in AC 27-1B, Certification of Normal Category Rotorcraft);
and AC 29.1322 (in AC 29-2C, Certification of Transport Category Rotorcraft) 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 flightcrew 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.
4.1.5.4 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 flightcrew, and enable the flightcrew to detect and correct errors that do occur. System interface design must also be evaluated to ensure dual entry of the Mode 3/A code, IDENT, and emergency status does not introduce significant additional workload, and that the controls are acceptable for data entry, accuracy, and error rates, particularly when communicating an aircraft emergency.
Evaluations should consider pilot-detected and undetected error rates, pilot workload, and training times. Refer to section 3.7.3.5 of this AC for additional information on transponder and ADS-B system single point of entry.
4.1.5.5 Lighting.
Evaluate all foreseeable conditions relative to lighting, including failure modes such as lighting and power system failure, and day and night operations.
4.1.6 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 replies to the Mode A/C and ATCRBS/Mode S all-call interrogations are inhibited on the ground.
4.1.7 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, ensure both the transponder and ADS-B system 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.
4.1.8 Self Test.
Evaluate the ADS-B self-test features (if provided) and failure mode annunciations to ensure the pilot is able to determine whether the system is functioning properly.
4.1.9 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.
4.1.10 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.
4.1.11 Transmit Power.
Transmit power testing must be accomplished if a new antenna has been installed, an existing antenna has been relocated, 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:
40 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.
4.1.11.1 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
4.1.11.2 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
4.1.12 TCAS.
If a TCAS II system is installed on the aircraft, ensure 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.
4.1.13 Transponder All-call Inhibit.
When ADS-B functionality resides in a Mode S transponder, conduct a test demonstrating 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.
4.1.14 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.
This section provides information on flight testing ADS-B systems.
4.2.1 Electromagnetic Interference.
During all phases of flight, survey the flight deck EMI to determine that the ADS-B OUT equipment is not a source of objectionable conducted or radiated interference to previously installed systems or equipment, and that operation of the ADS-B OUT equipment is not adversely affected by conducted or radiated interference from previously installed systems and equipment.
4.2.2 Other System Performance.
Demonstrate the proper performance of any previously installed aircraft systems 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 systems, and does not require a unique test for ADS-B.
4.2.3 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 the same Mode 3/A code, IDENT, and emergency codes are transmitted from both systems.
4.3 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 dropouts, and the information transmitted is complete and correct. Currently the only method available to accomplish
42 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.
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.
4.3.1 Preflight Coordination.
4.3.1.1 Data Retrieval.
Flight test data can be requested for two distinct types of flight testing, operational checkout of a previously certified system, and testing of a first-of-kind ADS-B system.
4.3.1.1.1 Previously Certified Systems.
In the context of this AC, a previously certified system is an ADS-B system that holds a Type Certificate, Supplemental Type Certificate or is listed on an Approved Model Listing. Aircraft owners may request a flight test compliance report to verify a previously approved ADS-B system has been installed and configured correctly. Interested parties can email 9-AWA-AFS-300-ADSB-AvionicsCheck@faa.gov and request an ADS-B Aircraft Operation Compliance Report (ACR). When requesting an ACR, include aircraft registration number (“N” number), location, date, and approximate local time of flight. All requests should be made after the test flight has taken place.
4.3.1.1.2 First-of-Kind Systems.
System integration teams may request flight test data for first-of-kind ADS-B systems. First-of-kind systems are those that are part of a TC, STC, or Approved Model List (AML) effort. At least 48 hours before the flight, notify the FAA by emailing 9-avs-air-130flttest@FAA.gov that you require data to support first-of-kind testing of a new ADS-B system.
Contacting the FAA before a test flight will better ensure flight test data will be provided in a timely manner. Upon initial contact, the FAA will provide a flight test request sheet. When contacting the FAA for flight test data, it is recommended you carbon copy any certifying officials you may be working with within the Aircraft Certification Office, Military Certification Office, Flight Standards District Office, or Flight Inspection District Office. Flight test data can usually be provided to the requester within 48 hours. An analysis report may take up to 30 days if it is determined necessary.
4.3.1.2 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.
4.3.2 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 section 4.3.2.3 through
4.3.4.6 below may be flown in any order.
4.3.2.1 Location of Flight.
The flight may be accomplished in any airspace that has FAA ADS-B ground station coverage. As of December 1, 2015 the ADS-B ground network is completely deployed across the continental United States, Hawaii, Puerto Rico, and Guam. The ADS-B ground network has been installed in Alaska but does not cover the entire state. Refer to the following website for information on existing ADS-B coverage in the National Airspace System (NAS):
http://www.faa.gov/nextgen/programs/adsb/coverageMap/
4.3.2.2 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.
4.3.2.3 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.
4.3.2.4 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 below provides the 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.