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 .
(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.
(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) 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; rather you must show that they compare reasonably, and that there are no gross geometric altitude errors.
(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.
(6) Validity checks. The FAA plans to utilize 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 an enhanced validity status is provided in the flight test data, then 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 14 CFR 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 paragraph 4-3 apply to initial STC/TC applications. Flight test data from a similar installation, covered under a previous STC, may be used in-lieu-of a new flight test if the following conditions can be confirmed through the documentation of the previous STC:
a. The position source must be identical to that of the other STC documentation. Equipment families that use the same baseline design may make a case for equivalence.
b. The ADS-B equipment must be identical to that of the other STC/TC documentation.
Equipment families that use the same baseline design may make a case for equivalence.
c. 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 STC. Aircraft with data concentrators will have to re-accomplish the flight test, even if the equipment is identical.
d. The air-data interface to the ADS-B equipment must be identical to that of the previous 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 that broadcast of simulated altitude information does not cause interference with ATC or ADS-B IN applications.
e. The heading interface to the ADS-B equipment (if applicable) must be identical to that of the previous 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.
f. The TCAS interface to the ADS-B equipment must be identical to that of the previous STC.
The TCAS equipment may be different, only the interface to the ADS-B equipment needs to be identical.
Appendix 1 A1-1 Appendix 1. Message Elements Descriptions
1. Purpose. This appendix provides a description of the message elements that may be contained in an ADS-B message.
2. Message Elements.
a. 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 14 CFR
91.227.
b. 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.
c. 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 14 CFR 91.227.
d. 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 14 CFR 91.227 except when using the TSO-C154c anonymity feature.
e. 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 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 14 CFR 91.227.
f. 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 14 CFR 91.227.
Appendix 1 A1-2
g. 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 WGS-84 ellipsoid (HAE). Geometric altitude is required to be transmitted by 14 CFR 91.227.
h. Geometric vertical accuracy (GVA). The GVA indicates the 95% accuracy of the reported vertical position (geometric altitude) within an associated allowance.
i. GNSS antenna offset and position offset applied.
(1) The GNSS antenna offset indicates the longitudinal distance between the nose of the aircraft and the GNSS antenna and the lateral distance between the longitudinal center line of the aircraft and the GNSS antenna.
(2) The position offset applied 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. See RTCA/DO-242A, Min Aviation System Performance Standards for ADS-B, change 1, paragraph 2.1.2.5 and figure 2-1 for a depiction of the ADS-B position reference point.
j. 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.
k. 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 in order to transmit complete velocity information.
l. 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 in order to transmit complete velocity information.
m. 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 14 CFR 91.227.
n. ICAO 24-bit address. 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 the 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
Appendix 1 A1-3 ICAO 24-bit address is required to be transmitted by 14 CFR 91.227 except when using the TSO-C154c anonymity feature.
o. IFR capability. This parameter existed in TSO-C166a and TSO-C154b compliant equipment, however it was removed from TSO-C166b and TSO-C154c equipment.
p. IDENT. 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 controllers screen. IDENT is required to be transmitted by 14 CFR 91.227.
q. 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 World Geodetic System 1984 (WGS-84) ellipsoid. Latitude and longitude are required to be transmitted by 14 CFR 91.227.
r. 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 14 CFR 91.227.
s. 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 - 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 14 CFR 91.227.
t. 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% probability that the reported information is correct within an associated allowance. A minimum NACP value of eight must be transmitted to operate in airspace defined in 14 CFR 91.225. Table 9 provides the applicable NACP values.
Appendix 1 A1-4
Table 9. NACP Values
u. 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 is no vertical rate accuracy metric. A NACV of greater than or equal to 1 is required by 14 CFR 91.227.
v. Navigation Integrity Category (NIC). The NIC parameter specifies a position integrity containment radius. NIC is reported so that 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 horizontal protection level (HPL) from the GNSS. A minimum NIC value of seven must be transmitted to operate in airspace defined in 14 CFR 91.225. Table 10 provides the applicable NIC 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
Appendix 1 A1-5
Table 10. NIC Values
NIC Containment Radius 0 Unknown 1 R C < 37.04 km (20nm) 2 R C < 14.816 km ( 8nm) 3 R C < 7.408 km (4nm) 4 R C < 3.704 km (2nm) 5 R C < 1852 m (1nm) RC < 1111.2 m (0.6nm) RC < 926 m (0.5nm) 6 RC < 555.6 m (0.3nm) 7 R C < 370.4 m (0.2nm) 8 R C < 185.2 m (0.1nm) 9 R C < 75 m 10 R C < 25 m 11 R C < 7.5 m
w. 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.
x. 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 World Geodetic System 1984 (WGS-84) ellipsoid. Latitude and longitude is required to be transmitted by 14 CFR 91.227.
y. Receiving ATC services. 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, however it was removed from TSO-C166b and TSO-C154c equipment.
z. Single antenna bit. Indicates if the ADS-B equipment is transmitting through a single antenna.
aa. 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 un-annunciated faults in the avionics system, the SIL must consider the effects of a faulted Signal-In-Space (SIS), if a signal-inspace is used by the position source. A minimum SIL value of three must be transmitted to operate in airspace defined in 14 CFR 91.225. Table 11 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,
Appendix 1 A1-6 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 11. SIL Values, Probability of Exceeding the NIC Containment Radius.
SIL Value Probability of exceeding the NIC containment radius 3 ≤ 1x10-7 Per Hour or Sample 2 ≤ 1x10-5 Per Hour or Sample 1 ≤ 1x10-3 Per Hour or Sample 0 > 1x10 -3 Per Hour or Sample or Unknown
bb. 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 12.
Table 12. Source Integrity Level Supplement
SIL Supplement Basis for SIL Probability 1 Probability of exceedin g NIC containment radius is based on per sample 0 Probability of exceeding NIC contai nment radius is based on per hour
cc. System Design Assurance (SDA). The SDA parameter defines the failure condition that the ADS-B system is designed to support as defined in table 13. 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. Since 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 potential impact of an erroneous position report caused by an equipment malfunction. The definitions and probabilities associated with the supported failure effect are defined in AC 25.1309-1, System Design and Analysis, AC 23.1309-1(), System Safety Analysis and Assessment for Part 23 Airplanes, and AC 29-2, Certification of Transport Category Rotorcraft (Changes 1-3 incorporated). The SDA includes the position source, ADS-B equipment, and any intermediary devices that process the position data. 14 CFR 91.227 requires a SDA of 2 or 3 as defined in table 13.
Appendix 1 A1-7
Table 13. System Design Assurance
SDA Value Supported Failure Condition Note 2 Probability of Failure causing transmission of False or Misleading Information Note 3,4 Software & Hardware Design Assurance Level Note 1,3 3 Hazardous ≤ 1x10-7 Per Hour B 2 Major ≤ 1x10-5 Per Hour C 1 Minor ≤ 1x10-3 Per Hour D 0 Unknown/ No safety effect > 1x10-3 Per Hour or Unknown N/A
Note: 1: Software design assurance per RTCA/DO-178B, Software Considerations in Airborne Systems and Equipment Certification, or equivalent.
Airborne electronic hardware design assurance per RTCA/DO-254, Design Assurance Guidance for Airborne Electronic Hardware, or equivalent.
Note: 2: Supported failure classification defined in AC 25.1309-1, AC 23.1309-1, and AC 29-2.
Note: 3: Because the broadcast position can be used by any other ADS-B equipped aircraft or by ATC, the provisions in AC 23.1309-1() that allow reduction in failure probabilities and design assurance level for aircraft under 6,000 pounds do not apply for the ADS-B system.
Note: 4: Includes probability of transmitting false or misleading latitude, longitude, or associated position accuracy and integrity metrics.
dd. TCAS installed and operational. This parameter indicates whether the aircraft is fitted with a TCAS II and if the TCAS II is turned on and operating in a mode that can generate resolution advisory alerts. The TCAS installed and operational parameter is required to be transmitted by 14 CFR 91.227.
ee. TCAS traffic status. This parameter indicates if a TCAS II equipped aircraft is currently generating a TCAS resolution advisory. The TCAS traffic status parameter is required to be transmitted by 14 CFR 91.227 if the aircraft is TCAS II equipped.
ff. Trajectory change report capability. This information is permanently set to zero in TSO-C166b or TSO-C154c equipment. No installation interface is required. Trajectory change reports are reserved for future use.
gg. Vertical rate. The barometric or geometric rate at which the aircraft is climbing or descending, measured in feet per minute. The vertical rate is typically generated by an air data computer or GNSS position source, or equipment which blends barometric vertical rate with inertial vertical rate and/or GNSS vertical rate.
Appendix 1 A1-8 hh. Version number. The applicable TSO Minimum Operational Performance Standard (MOPS) level is communicated through the version number, which is fixed at the time the ADS-B equipment is manufactured. Version two applies to ADS-B equipment that meets MOPS documents RTCA/DO-260B with Corrigendum 1 or RTCA/DO-282B with corrigendum 1.
ADS-B equipment outputting version two or higher is required by 14 CFR 91.227.
Appendix 2 A2-1 Appendix 2. Identifying and Qualifying ADS-B Position Sources
1. Purpose. This appendix defines the minimum requirements for position sources interfaced to ADS-B systems. The appendix also defines appropriate position source qualification methods when the existing GNSS TSOs do not contain specific requirements or test procedures. The position source manufacturer should provide design data where appropriate, preferably in the GNSS equipment installation manual, so that the installer can properly interface the position source to the ADS-B system. Position source suppliers must ensure that any supplied data is incorporated into the article design, and changes to any documented characteristics result in a change to the part number.
2. Organization. This appendix includes general guidance that applies to all position sources, as well as GNSS specific guidance. The appendix also provides high level requirements for tightly coupled GNSS/IRU position sources and non-GNSS position sources. All references in this AC to TSO-C129, TSO-C145, TSO-C146, and TSO-C196 refer to any revision of the TSO.
3. General Guidance for all Position Sources. All ADS-B position sources should provide the following outputs.
a. Position. The position source must provide a latitude and longitude output.
Requirements and test procedures in TSO-C129/145/146/196 are sufficient and GNSS equipment with Technical Standard Order Authorization (TSOA) for the aforementioned TSOs require no additional qualification for the position output.
b. Horizontal velocity. The position source must output north/south and east/west velocities. We recommend the position source also output the velocity in a ground speed and track angle format.
c. Position accuracy (horizontal). The position source must have a horizontal position accuracy output, and the output must have been qualified during the system’s TSO authorization or design approval. This output must describe the radius of a circle in the horizontal plane, with its center being at the true position which describes the region assured to contain the indicated horizontal position with at least 95% probability under fault-free conditions.
d. Position accuracy (vertical). The position source should output a vertical position accuracy metric. The vertical position accuracy metric must have been qualified during the system’s TSO authorization or design approval. This output must describe the vertical position accuracy with 95% probability under fault-free conditions.
e. Position integrity (horizontal). The position source must have a horizontal position integrity output qualified during the system’s TSO authorization or design approval. This integrity output should describe the radius of a circle in the horizontal plane, with its center being at the true position which describes the region assured to contain the indicated horizontal position with at least 99.99999% probability under fault-free avionics conditions. Position sources which degrade from a 99.99999% probability to a 99.999% probability (e.g., a tightlycoupled inertial/GNSS system after the loss of GNSS) can still be installed, however they won’t meet 14 CFR 91.227 following the degradation. In this case, the position source must have a