44 Table 5. Turns Part 23 Aircraft Configuration Altitude Range (in feet AGL) Speed Range Bank Angle Takeoff 3000-5000 1.4 VS 30° Approach or Landing 2000-7000 1.4 VS 30° Cruise 7000-10000 1.5 VS to 1.8 VS 30° Part 25 Aircraft Configuration Altitude Range Speed Range Bank Angle Takeoff 3000-5000 V2 + 20 kts 30° Approach or Landing 2000-7000 VAPP + 20 kts 30° Cruise 7000-10000 1.5 VS to 1.8 VS 30° Part 27 Rotorcraft Configuration Altitude Range Speed Range Bank Angle Landing 1000-3000 VY + 10 kts 30° Cruise 2000-5000 0.8 VNE or 0.8 VH 30° Part 29 Rotorcraft Configuration Altitude Range Speed Range Bank Angle Landing 1000-3000 VY + 10 kts 30° Cruise 2000-10000 0.8 VNE or 0.8 VH 30°
4.3.2.5 Climbs/Descents.
Verify the ADS-B system performs properly during climbs and descents.
Table 6 provides a suggested airspeed at which climbs should be made during the test flight. Table 7 provides a suggested airspeed 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.
45 Table 6. Climb Speeds Configuration Part 23 Aircraft Part 25 Aircraft Part 27 Rotorcraft Part 29 Rotorcraft Take off VY VFE - 10 kts VY VY Cruise VH VMO - 10 kts 0.8 VNE or 0.8 VH 0.8 VNE or 0.8 VH Table 7. Descent Speeds Configuration Part 23 Aircraft Part 25 Aircraft Part 27 Rotorcraft Part 29 Rotorcraft Cruise VNE - 10 VMO - 10 kts 0.8 VNE or 0.8 VH 0.8 VNE or 0.8 VH Approach VFE - 10 VFE - 10 kts VY + 10 kts VY + 10 kts Landing VFE - 10 VFE - 10 kts N/A N/A
4.3.2.6 Position Accuracy.
Using a known waypoint, fly a north/south course that crosses the defined waypoint followed by an east/west course that crosses the same defined waypoint.
4.3.3 Post-Flight Data Analysis.
You must accomplish a post-flight data analysis to ensure 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 by 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:
4.3.3.1 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 when 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
46 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, 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, the applicant must establish root cause and provide a solution before granting installation approval. Demonstrate that you meet all § 91.227(c)(1) accuracy and integrity requirements, listed in Table 8, during flight.
Table 8. Accuracy and Integrity Requirements During Flight Ensure NIC ≥ 7 throughout the flight. Rc <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
4.3.3.2 Position Accuracy/Integrity.
Compare the track received by the FAA ground system with the actual flight track. There is no specific tolerance for this test; rather, the applicant must show there are no gross position errors, track offsets or discontinuities, or other obvious anomalies.
4.3.3.3 Velocity Accuracy.
Compare the velocity received by the FAA ADS-B ground system with the actual velocities flown. There is no specific tolerance for this test;
rather, you must show that they compare reasonably, and that there are no gross velocity errors.
4.3.3.4 Geometric Altitude Accuracy.
Compare the geometric altitude received by the FAA ground system with the geometric altitude flown. There is no specific tolerance for this test;
47 rather, you must show that they compare reasonably, and that there are no gross geometric altitude errors.
4.3.3.5 Barometric Pressure Altitude Accuracy.
Compare the barometric pressure altitude received by the FAA ground system with the actual barometric pressure altitude flown. There is no specific tolerance for this test; rather, you must show that they compare reasonably, and that there are no gross barometric pressure altitude errors.
4.3.3.6 Validity Checks.
The FAA plans to use radar, multilateration, and UAT passive ranging as independent validity checks for ADS-B. The validity check will indicate “valid” when the independent check is able to validate the ADS-B position, “invalid” when it determines the ADS-B position is out of tolerance, and “unknown” if it is unable to accomplish the validity check.
If a validity or enhanced validity status is provided in the flight test data, you must show that it never indicates “invalid”.
Note: Validity checks are planned to ensure the ADS-B position is within
0.56 nm in terminal airspace and 1.9 nm in en-route airspace. Enhanced validity checks are planned to ensure the ADS-B position is within 0.2 nm within approximately 15 nm of terminal radars and close proximity to airports with Airport Surface Detection Equipment, Model X (ASDE-X) systems.
4.4 International Flight Test Options.
If the aircraft is being flight tested outside of the United States, it is acceptable to perform the flight test against another Air Navigation Service Provider’s (ANSP) ground system. Other ANSP’s ground systems must be fully operational and appropriately qualified to provide ATC separation services. Other ANSP ground systems must also be able to provide all parameters required by § 91.227. You will have to work with the foreign ANSP to retrieve the necessary data.
4.5 Subsequent Flight Test Data Reuse.
The flight test guidelines in section 4.3 of this AC apply to initial TC/STC applications.
Flight test data from a similar installation, covered under a previous TC/STC, may be used instead of a new flight test if the following conditions can be confirmed through the documentation of the previous STC:
4.5.1 Position Source Equipment.
The position source must be identical to that of the other Amended Type Certificate (ATC), TC, or STC documentation. Equipment families that use the same baseline design may make a case for equivalence.
4.5.2 ADS-B Equipment.
The ADS-B equipment must be identical to that of the other ATC/TC/STC documentation. Equipment families that use the same baseline design may make a case for equivalence.
4.5.3 System Interface.
A direct interface must be used between the position source and the ADS-B equipment, and that interface must be identical to that of the previous ATC/TC/STC. Aircraft with data concentrators will have to re-accomplish the flight test, even if the equipment is identical.
4.5.4 Air-Data Interface.
The air-data interface to the ADS-B equipment must be identical to that of the previous ATC/TC/STC. The actual air-data source may be different equipment; only the interface to the ADS-B equipment needs to be identical. However, if the air-data source is different, more extensive ground testing should be accomplished, to include a dynamic test where the air-data source has simulated inputs from sea level to the maximum certified operating altitude of the aircraft. Care should be taken to ensure broadcast of simulated altitude information does not cause interference with ATC or ADS-B IN applications.
4.5.5 Heading Interface.
The heading interface to the ADS-B equipment (if applicable) must be identical to that of the previous ATC/TC/STC. The heading source may be different; only the interface to the ADS-B equipment needs to be identical. If the heading source is different, testing should be accomplished, to include positioning the aircraft at multiple headings on the surface to verify heading accuracy.
4.5.6 TCAS Interface.
The TCAS interface to the ADS-B equipment must be identical to that of the previous ATC/TC/STC. The TCAS equipment may be different; only the interface to the ADS-B equipment needs to be identical.
Appendix A A-1 APPENDIX A. MESSAGE ELEMENT DESCRIPTIONS A.1 Purpose.
This appendix provides a description of the message elements that may be contained in an ADS-B OUT message.
A.2 Message Elements.
A.2.1 ADS-B IN Capability.
Two messages indicate the ADS-B IN status of the aircraft. The 1090 ADS-B IN message indicates if the aircraft has the ability to receive 1090ES ADS-B messages installed. The UAT ADS-B IN message indicates if the aircraft has the ability to receive UAT ADS-B messages installed. An indication of ADS-B IN capability is important because TIS-B and ADS-R services are provided specific to an aircraft’s position relative to other aircraft. The FAA may only provide complete TIS-B and ADS-R services to aircraft that indicate they are ADS-B IN capable. ADS-B IN capability is required to be transmitted by § 91.227.
A.2.2 Airspeed.
Optionally, true airspeed or indicated airspeed may be transmitted. The airspeed source should be approved to output airspeed data. An air data computer meeting the minimum performance requirements of TSO-C106 is one acceptable source. Do not interface an airspeed source to the ADS-B that has not been approved for cockpit display.
A.2.3 Barometric Pressure Altitude.
This parameter indicates the aircraft’s barometric pressure altitude referenced to standard sea level pressure of 29.92 inches of mercury or 1013.2 hectopascals. The barometric pressure altitude is required to be transmitted by § 91.227.
A.2.4 Call Sign/Flight ID.
The term “aircraft call sign” is the radiotelephony call sign assigned to an aircraft for voice communications purposes. (This term is sometimes used interchangeably with “flight identification” or “flight ID”). For general aviation aircraft, the aircraft call sign is normally the national registration number; for airline and commuter aircraft, the call sign is usually comprised of the company identification and flight number (and therefore not linked to a particular airframe) and, for the military, it usually consists of numbers and code words with special significance for the operation conducted. The call sign or aircraft registration number is required to be transmitted by § 91.227 except when using the TSO-C154c anonymity feature.
A.2.5 Emergency Status.
This parameter alerts ATC that the aircraft is experiencing emergency conditions and indicates the type of emergency. Applicable emergency codes are found in ICAO
Appendix A A-2 Annex 10 Volume 4, Surveillance Radar and Collision Avoidance Systems. This information alerts ATC to potential danger to the aircraft so it can take appropriate action. Emergency status is required to be transmitted by § 91.227.
A.2.6 Emitter Category.
The emitter category provides an indication of the aircraft’s size and performance capabilities. Emitter categories are defined in TSO-C166b and TSO-C154c. Emitter category is designed primarily to provide information on the wake turbulence that an aircraft produces. Emitter category is required to be transmitted by § 91.227.
A.2.7 Geometric Altitude.
The geometric altitude is a measure of altitude provided by a satellite-based position service and is not affected by atmospheric pressure. Geometric altitude is only available with a GNSS position source. Geometric altitude for ADS-B purposes is the height above the World Geodetic System 1984 (WGS-84) ellipsoid (HAE). Geometric altitude is required to be transmitted by § 91.227.
A.2.8 Geometric Vertical Accuracy (GVA).
The GVA indicates the 95-percent accuracy of the reported vertical position (geometric altitude) within an associated allowance.
A.2.9 GNSS Antenna Offset and Position Offset Applied (POA).
A.2.9.1 The GNSS antenna offset indicates the longitudinal distance between the most forward part of the aircraft and the GNSS antenna, and the lateral distance between the longitudinal center line of the aircraft and the GNSS antenna. Also, refer to section 3.8.4.1 – 3.8.4.3 and Figure 3 of this AC.
A.2.9.2 The POA setting of the GNSS antenna offset indicates that the broadcast position is referenced to the aircraft’s ADS-B position reference point versus the GNSS antenna location. Also, refer to section 3.8.4.1 -
3.8.4.3and Figure 3 of this AC. For further details about POA, refer to RTCA/DO-338, section 3.2.4.1.
A.2.10 Ground Speed.
This parameter is also derived from the position sensor and provides ATC with the aircraft’s speed over the ground. This parameter is reported in the surface position message.
A.2.11 Ground Track Angle.
The ground track angle is the direction of the horizontal velocity vector over the ground. Ground track or heading is required to be transmitted while on the ground to transmit complete velocity information.
Appendix A A-3 A.2.12 Heading.
Heading indicates the direction in which the nose of the aircraft is pointing. There is no heading accuracy metric. Heading or ground track is required to be transmitted while on the ground to transmit complete velocity information.
A.2.13 Horizontal Velocity.
The horizontal velocity provides the rate at which an aircraft changes its horizontal position with a clearly stated direction. Horizontal velocity is provided with the north/south velocity and the east/west velocity parameters while airborne. Horizontal velocity is provided by a combination of the ground speed and heading or ground track while on the surface. TSO-C166b and TSO-C154c require that the north/south velocity, east/west velocity, ground speed, and ground track come from the same source as the position. Heading information may come from a separate source. Horizontal velocity is required to be transmitted by § 91.227.
A.2.14 ICAO 24-bit Address.
The ICAO 24-bit address is a unique address assigned to an aircraft during the registration process. ICAO 24-bit addresses are defined blocks of addresses assigned for participating countries or states worldwide. In the United States, civil aircraft are assigned an address from an encoding scheme based on the aircraft registration number (“N” number). Additional information regarding the 24-bit address can be found in ICAO Annex 10, Part I, Volume III, appendix to Chapter 9, A World-Wide Scheme for the Allocation, Assignment and Application of Aircraft Addresses. The ICAO 24-bit address is required to be transmitted by § 91.227 except when using the TSO-C154c anonymity feature.
A.2.15 IFR Capability.
This parameter existed in TSO-C166a and TSO-C154b compliant equipment, but was removed from TSO-C166b and TSO-C154c equipment.
A.2.16 IDENT.
IDENT is a flag manually set by the pilot at the request of ATC in ATCRBS, Mode S, and ADS-B messages. The pilot manually enables the IDENT state, which highlights their aircraft on the controller’s screen. IDENT is required to be transmitted by § 91.227.
A.2.17 Latitude and Longitude.
These parameters are derived from the position source and provide a geometric based position. Reference all geometric position elements broadcast from the ADS-B unit to the WGS-84 ellipsoid. Latitude and longitude are required to be transmitted by §
91.227.
A.2.18 Length and Width of Aircraft.
This parameter provides ATC and other aircraft with quick reference to the aircraft’s dimensions while on the surface. Aircraft length and width is required to be transmitted by § 91.227.
Appendix A A-4 A.2.19 Mode 3/A Code.
Currently ATC automation relies on the Mode 3/A code to identify aircraft under radar surveillance and correlate the target to a flight plan. The mode 3/A code is a four digit number ranging from 0000 to 7777. Secondary Surveillance Radars (SSR) and ADS-B will concurrently provide surveillance, so the Mode 3/A code is included in the ADS-B OUT message and is required to be transmitted by § 91.227.
Note: ADS-B systems will not transmit the Mode 3/A code if the Mode 3/A code is set to 1000.
A.2.20 Navigation Accuracy Category for Position (NACP).
The NACP specifies the accuracy of the aircraft’s horizontal position information (latitude and longitude) transmitted from the aircraft’s avionics. The ADS-B equipment derives a NACP value from the position source’s accuracy output, such as the HFOM from the GNSS. The NACP specifies with 95 percent probability that the reported information is correct within an associated allowance. A minimum NACP value of “8” must be transmitted to operate in airspace defined in § 91.227. Table A-1 provides the applicable NACP values.
Table A-1. NACP Values NACP Horizontal Accuracy Bound 0 EPU ≥ 18.52 km (10nm) 1 EPU < 18.52 km (10nm) 2 EPU < 7.408 km (4nm) 3 EPU < 3.704 km (2nm) 4 EPU < 1852 m (1nm) 5 EPU < 926 m (0.5nm) 6 EPU < 555.6 m (0.3nm) 7 EPU < 185.2 m (0.1nm) 8 EPU < 92.6 m (0.05nm) 9 EPU < 30 m 10 EPU < 10 m 11 EPU < 3 m
A.2.21 Navigation Accuracy Category for Velocity (NACV).
The NACV is an estimate of the accuracy of the horizontal geometric velocity output.
The coding of “ZERO,” indicating that the accuracy is unknown or either equal to or worse than 10 meters per second (m/s), is of little value to ADS-B applications. There
Appendix A A-5 is no vertical rate accuracy metric. A NACV of greater than or equal to “1” is required by § 91.227. Table A-2 provides the applicable NIC values Table A-2. NACV Value Velocity Accuracy Bound (Estimated Velocity Uncertainty) 0 ≥ 10 m/s or unknown 1 < 10 m/s 2 < 3 m/s 3 < 1 m/s 4 < 0.3 m/s
A.2.22 Navigation Integrity Category (NIC).
The NIC parameter specifies a position integrity containment radius. NIC is reported so surveillance applications, such as ATC or other aircraft, may determine whether the reported geometric position has an acceptable level of integrity for the intended use.
The NIC parameter is closely associated with the SIL. While NIC specifies the integrity containment radius, SIL specifies the probability of the actual position lying outside that containment radius without indication. ADS-B systems should derive the NIC from an approved position source’s integrity output, such as the HPL from the GNSS. A minimum NIC value of “7” must be transmitted to operate in airspace defined in § 91.225. Table A-3 provides the applicable NIC values.
Appendix A A-6 Table A-3. NIC Values NIC Containment Radius 0 Unknown 1 RC < 37.04 km (20.0 nm) 2 RC < 14.816 km ( 8.0 nm) 3 RC < 7.408 km ( 4.0 nm) 4 RC < 3.704 km ( 2.0 nm) 5 RC < 1.852 km ( 1.0 nm) 6 Sup A=1 Sup B=1 RC < 1111.2 m ( 0.6 nm) 6 Sup A=0 Sup B=0 RC < 926 m ( 0.5 nm) 6 Sup A=0 Sup B=1 RC < 555.6 m ( 0.3 nm) 7 RC 370.4 m ( 0.2 nm) 8 RC < 185.2 m ( 0.1 nm) 9 RC < 75 m 10 RC < 25 m 11 RC < 7.5 m A.2.23 NICBARO.
NICBARO indicates if pressure altitude is provided by a single Gillham encoder or another more robust altitude source. Because of the potential for an undetected error in a Gillham encoding, many Gillham installations are cross-checked against a second altitude source. NICBARO annotates the status of this cross-check.
A.2.24 Position.
These parameters are derived from the position source and provide a geometric based position. Reference all geometric position elements broadcast from the ADS-B unit to the WGS-84 ellipsoid. Latitude and longitude is required to be transmitted by § 91.227.
A.2.25 Receiving ATC Services.
This parameter is a bit set in the ADS-B system of an aircraft indicating that the Mode A code is not set to “1200”. This parameter existed in TSO-C166a and TSO-C154b compliant equipment, but was removed from TSO-C166b and TSO-C154c equipment.
A.2.26 Single Antenna Bit.
This parameter indicates if the ADS-B equipment is transmitting through a single antenna.
Appendix A A-7 A.2.27 Source Integrity Level (SIL).
The SIL field defines the probability of the reported horizontal position exceeding the radius of containment defined by the NIC, without alerting, assuming no avionics faults.
Although the SIL assumes there are no unannunciated faults in the avionics system, the SIL must consider the effects of a faulted Signal-In-Space (SIS), if a SIS is used by the position source. A SIL value of “3” must be transmitted to operate in airspace defined in § 91.225. Table A-4 outlines the SIL values.
Note 1: The probability of an avionics fault causing the reported horizontal position to exceed the radius of containment defined by the NIC, without alerting, is covered by the SDA parameter.
Note 2: The SIL probability can be defined as either per sample or per-hour as defined in the SIL supplement (SILSUPP).
Table A-4. SIL Values, Probability of Exceeding the NIC Containment Radius SIL Value Probability of exceeding the NIC containment radius 0 > 1x10-3 Per-hour or Sample or Unknown 1 ≤ 1x10-3 Per-hour or Sample 2 ≤ 1x10-5 Per-hour or Sample 3 ≤ 1x10-7 Per-hour or Sample A.2.28 Source Integrity Level Supplement (SILSUPP).
The SILSUPP defines whether the reported SIL probability is based on a per-hour probability or a per-sample probability as defined in Table A-5.
Table A-5. Source Integrity Level Supplement SIL Supplement Basis for SIL Probability 0 Probability of exceeding NIC containment radius is based on per-hour.
1 Probability of exceeding NIC containment radius is based on per-sample.
A.2.29 System Design Assurance (SDA).
The SDA parameter defines the failure condition that the ADS-B system is designed to support as defined in Table A-5. The supported failure condition will indicate the probability of an ADS-B system malfunction causing false or misleading position information or position quality metrics to be transmitted. This should include the probability of exceeding the containment radius without annunciation. Because the installer of ADS-B OUT equipment does not know how the broadcast data will be used, the installer cannot complete a Functional Hazard Assessment (FHA) evaluating the use of the broadcast data. The SDA provides a surrogate for such a FHA by identifying the