(c) The flight crew should be able to return to the previous state by a simple action.
(d) If automatic decluttering is implemented, a means should be provided for the flight crew to control the automated decluttering function.
(e) An indication that decluttering is active must be provided.
(5) A means to pan the view. If panning is implemented:
(a) There must be a means to control panning.
(b) There must be a means to return to the original view with a simple action.
(6) A means to designate traffic for an application (e.g. CAVS).
2-5. Alerts.
a. Alerts should be consistent with the flight deck alerting system and philosophy, and should not interfere with higher priority alerts. Advisory Circular 25.1322-1, Flightcrew Alerting, contains guidance for flight crew alerting functions.
b. Each ATAS alert must include a visual caution level alert either on the Traffic Display or on an annunciator panel in an aural-only implementation.
c. Each ATAS aural alert should be annunciated by a dedicated voice message consistent with the requirements in TSO-C195b. The voice message will be annunciated over a cockpit speaker and through a headset/helmet at a volume adequate for clear understanding at high cockpit noise levels, but not excessively loud at low noise levels.
The evaluation of the message annunciated through a cockpit speaker includes the case where a flight crew member is wearing a headset covering the outboard ear, when appropriate. ATAS aural alerts provide bearing, range, relative altitude, and optionally, a vertical sense of the alerted traffic. Vertical sense of the alerted traffic can be of three types: climbing, descending, or level.
d. ATAS installations must include a means to acknowledge an alert in progress that causes the aural to be discontinued.
e. ATAS installations must include a means to request an update of the aural alert to announce the new traffic state (bearing, range, relative altitude).
f. Aural alerts must be automatically inhibited by all higher priority alerts including alerts issued by TCAS II, if so equipped. Inhibit priorities for TCAS are established by AC 20-151(), Airworthiness Approval of Traffic Alert and Collision Avoidance Systems (TCAS II), Versions 7.0 & 7.1 and Associated Mode S Transponders.
2-6. Airborne Surveillance and Separation Assurance Processing (ASSAP).
The ASSAP subsystem accepts data from one or more sources including ADS-B reports, TIS-B reports, ADS-R reports, and TCAS tracks (if installed). ASSAP correlates data from these sources, generates tracks, and performs application-specific processing. Surveillance tracks and application-specific alerts or guidance are output by ASSAP to the CDTI function. The ASSAP equipment must be compliant with the Class C requirements of TSO-C195b and should be installed in accordance with manufacturer instructions. TCAS processors track transponderequipped aircraft. Therefore, TSO-C195b equipment requires installations with TCAS to provide these tracks to the ASSAP equipment to complete the traffic picture. TCAS in this AC is meant to apply to all versions of certified traffic advisory system (TAS) or TCAS compliant with TSO-C147(), TSO-C118(), or TSO-C119(). Hybrid surveillance TCAS are included. For aircraft installations without TCAS, the TIS-B service provides tracks of transponder-equipped aircraft.
2-7. ADS-B In Receiver and Antenna.
The installation must include a UAT (per TSO-C154c) or a 1090 ES (per TSO-C166b) receiver.
Ideally, installation of a dual-band receiver would allow for dual-link interoperability where ADS-R coverage is not provided. The ASSAP equipment may interface with the ADS-B receiver equipment or it may be integrated. If TCAS is installed, the ADS -B In equipment must contain or interface with the TCAS equipment so that the TCAS tracks may be used. Guidance material concerning the installation of the UAT or 1090ES equipment, and associated antenna(s), is provided in AC 20-165A.
2-8. Integration Considerations.
a. System Definition. ADS-B In installations include the ADS-B In receiver, antennas, traffic processor, control panels, audio system, and display components. All of these component part numbers must be identified as part of the integrated system. Any change to any of the components’ hardware or software requires evaluation of the potential impact to the ADS-B In function.
b. Equipment Compatibility Requirements. A critical component of the ADS-B In system is the position sensor. Compatibility between the sensor and the surveillance processor must be established by the equipment manufacturer(s) and detailed in an installation manual or supplement. Position source compatibility should consider the position source requirements in AC 20-165A. Compatibility between all other system components should be documented in an installation manual or supplement.
c. Aircraft Integration with ADS-B In System.
(1) Provide electrical power and grounding in accordance with the manufacturer’s installation manual. Conduct an electrical load analysis to verify that there is adequate power capacity for the ADS-B In equipment.
(2) The total latency to receive, process, and display traffic data must be less than
3.5 seconds. The traffic time of applicability must be within 1 second of the time of display.
The total latency of own-ship position at the display must be less than 3.5 seconds. The ownship time of applicability must be within 1 second of the time of display. Perform a latency analysis in accordance with Appendix A to demonstrate compliance. The total latency figures here are to be interpreted to mean when an ADS-B message is received. They do not address data age issues while the system is waiting to receive the next position report for an existing track. Data age and timeout requirements are handled separately for each application in TSO-C195b compliant equipment.
(3) The same position source used to provide ownship data for transmission on ADS-B Out should be used to provide position to the ASSAP equipment. Position sources interfaced to the ASSAP equipment must meet the quality metric requirements in DO-317B, section 2.2.4. Further guidance on integration with ADS-B position sources can be found in AC 20-165A. Future applications may require that ASSAP and the ADS-B Out equipment use the same position source. The FAA encourages applicants to plan accordingly to prevent extensive future redesign. An alternate position source may be used to provide ownship position to the CDTI display, but the accuracy, latency, and display time of applicability requirements still apply (refer to Appendix A). Provide connections in accordance with the manufacturer’s installation manual.
(4) The manufacturer’s instructions for strapping and/or programming of configurable aircraft parameters should be followed. Manufacturers are highly encouraged to provide instructions to installers for setting the global navigation satellite system (GNSS) antenna offset parameter during installation. The GNSS antenna offset information can be extremely valuable for ADS-B In surface situation awareness and future surface collision alerting applications on large aircraft with GNSS antenna far from the nose.
(5) Verify the equipment’s environmental qualifications (e.g., environmental categories of RTCA/DO-160( ) Environmental Conditions and Test Procedures for Airborne Equipment) are suitable for the aircraft type and equipment location.
(6) Record any limitations associated with use of the ADS-B In equipment in the Aircraft Flight Manual.
(7) ITP requests and clearances can only be granted using Direct Controller Pilot Communication (DCPC). Although it may be possible to perform ITP requests and clearances via voice communications, in most non-radar regions this means requests and clearances will be accomplished using Controller Pilot Datalink Communications (CPDLC). ITP requests can be lengthy and prone to typographical errors. It is recommended that ITP designs integrate the CDTI and data link systems in order to populate ITP requests automatically. An alternative is to provide the request text on the CDTI so that the flight crew can reference the text while entering the information manually. This reduces the possibility of human error while entering the ITP request. Examples of standardized free text CPDLC message formats for an ITP request (downlink message) can be found in Change 1 to RTCA/DO-306.
(8) When integrating TCAS II and ADS-B, design controls so that an operator can disable TCAS on the ground – as is currently required by TCAS operational guidance (AC 120-55(), Air Carrier Operational Approval and Use of TCAS II ) – while maintaining SURF ADS-B IN/CDTI functionality in an operational state.
d. System Safety Analysis. Unannunciated failures and hazardously misleading data must be improbable/remote for Class B and C equipment; but can be probable for Class A equipment. Loss of function can be probable for all classes. This can be shown using the methods described in AC 25.1309-1(), System Design and Analysis, AC 23.1309-1(), System Safety Analysis and Assessment for Part 23 Airplanes, AC 27-1B, Certification of Transport Category Rotorcraft, Change 3, or in AC 29-2C, Certification of Normal Category Rotorcraft, Change 3 as appropriate.
e. ATAS Installed In An Aircraft Equipped with a TCAS or TAS System.
(1) For aircraft equipped with either TCAS I, TCAS II, or TAS (hereafter just referred to as TCAS in this section unless context requires otherwise) and ATAS, consideration must be given to the encounters between ownship and an intruder(s) which could generate traffic alerts by both the TCAS equipment and the ATAS application for the same intruder. A matrix depicting traffic alerting capability of ownship that is possible when equipped with TCAS or ATAS independently is presented in Table 2. Operations both inside and outside of a TIS-B/ADS-R service volume are depicted for the two ADS-B links. Note that the table depicts traffic alerting capability that is independent of integration, i.e. when only TCAS or ATAS is installed. This table is meant to demonstrate the need for integration, not establish equipment design requirements.
Table 2. Traffic Alerting Capability of Ownship Ownship Intruder Ownship Functional Capability TC AS vari ant 1090 ES ADS-B In w/ATAS UAT ADS-B In w/ATAS Traffic information source TCAS I ------or----- TCASII ------or----- TAS Own is inside
TIS-B/ADS-R service volume Own is outside
TIS-B/ADS-R service volume Own is inside
TIS-B/ADS-R service volume Own is outside
TIS-B/ADS-R service volume Mode C X Mode S X 1090 ES X X
UAT X X
TIS-B X X ADS-R X (Note 3) X (Note 4) Notes:
1. An “X” indicates that the equipment will issue traffic alerts against that source.
2. The matrix depicts traffic alerts that ownship could generate.
3. Own receives UAT ADS-B out data via ADS-R.
4. Own receives 1090 ES ADS-B out data via ADS-R.
(2) When inside a TIS-B/ADS-R service volume, both TCAS and ATAS systems could issue alerts against intruders not equipped with ADS-B out avionics. Those alerts could occur in close succession or perhaps even simultaneously. If the aural traffic alerts for TCAS I, TCAS II, TAS and ATAS are not integrated when these systems are installed together, it could lead to pilot confusion. Therefore, when an ASA system is installed in aircraft equipped with TCAS, the systems must be integrated together to ensure that only one traffic system is alerting for a given aircraft. Appendix C contains examples of acceptable TCAS and ATAS configurations and an example of an invalid configuration.
Chapter 3. Test and Evaluation.
3-1. General.
Installation of an ADS-B In system should be accomplished on an aircraft with an ADS-B Out system. ADS-R and TIS-B services are only provided to aircraft that indicate, in their ADS-B Out messages, that they are an ADS-B In aircraft. This chapter assumes that the ADS -B Out system complies with AC 20-165A, and defines tests for the installed system.
3-2. Ground Tests.
a. Ground tests should be conducted on each aircraft installation. Ground tests should include the verification that ADS-B Out, ADS-R, and TIS-B message elements can be accurately received and processed. If ADS-B In equipment is integrated with TCAS, then TIS-B reception is not required for airborne traffic. However if the surface applications are implemented, TIS-B surface targets must be processed even by an installation that includes TCAS. Ground tests should include verification of the integration with a position sensor, since own-ship state data is used to generate the displayed data. In addition, any message elements that are presented on the CDTI display should be verified for accuracy. See AC 20-165A for a list and detailed explanation of each of the message elements. Ground test equipment should be capable of generating all of the different types of messages, including ADS-B Out, ADS-R, and TIS-B messages. If targets of opportunity are available to validate the ADS-B In functionality, they may be used in lieu of dedicated test equipment. Verify that the system receives and displays the following traffic information when stimulated appropriately:
(1) Relative horizontal position.
(2) Ground speed of traffic (if implemented).
(3) Directionality (Heading or Track Angle).
(4) Pressure altitude of airborne traffic relative to own-ship.
(5) Vertical trend of airborne traffic.
Note: ASSAP must indicate a climb/descent when traffic vertical velocity exceeds 500 feet per minute (fpm). Indication of vertical trend is allowed to occur at smaller vertical rates.
(6) Air/Ground status of traffic.
(7) Flight ID (if implemented).
(8) TIS-B/ADS-R service status (when not installed with TCAS).
(9) Differential ground speed (if implemented).
b. TCAS-equipped aircraft provide inputs to ASSAP. Verify that the system receives and displays the following information when stimulated appropriately:
(1) Traffic range.
(2) Traffic bearing.
(3) Traffic pressure altitude.
(4) Traffic vertical trend.
(5) TCAS alert status (i.e., no threat, proximity traffic, traffic advisory, or resolution advisory).
c. If the ADS-B In system supports the surface application, verify that the airport runways are depicted accurately. If taxiway data is available, verify that the airport taxiways are depicted accurately.
d. Evaluate simulated failures of the aircraft sensors integrated with the ADS-B In equipment to determine that the resulting system failure state agrees with the predicted results.
All system failures should be indicated clearly. The effects of system failures should be described in a manual.
e. Observe all of the electronic systems on the flight deck to determine that the ADS-B equipment is not a source of interference (conducted or radiated) to previously installed systems or equipment, and that operation of the ADS-B In equipment is not adversely affected by the previously installed systems and equipment.
f. Evaluate the general arrangement and operation of controls, displays, circuit breakers, indicators, and placards of the ADS-B In and CDTI equipment.
(1) Evaluate the ADS-B In system controls to determine that they are appropriately designed and located to prevent inadvertent actuation. Pay close attention to line select keys, touch screens, or cursor-controlled trackballs, as these can be susceptible to unintended mode selection resulting from their location in the flight deck (for example, proximity to a foot rest or adjacent to a temporary stowage area).
(2) Evaluate the CDTI display to ensure that all information is, at a minimum, legible, unambiguous, and attention-getting (as applicable).
(3) Evaluate the traffic symbols presented on the CDTI display for compliance with the standard recommended symbols from RTCA/DO-317B, which are summarized in Appendix B of this AC.
g. Evaluate the ADS-B In self-test features.
h. If possible, verify the dynamic performance of displayed traffic by observing any available ADS-B Out, ADS-R, TCAS (if installed), or TIS-B traffic in the area.
i. Evaluate the overall CDTI system installation for satisfactory accessibility and visibility under all lighting conditions.
j. For ATAS and CAVS installations, verify that aural alerts can be inhibited by higher priority alerts (e.g. TAWS, Windshear).
k. If implemented, evaluate selection and designation functionality.
l. For CAVS installations, the following data must be displayed in the pilot’s primary field of view:
(1) Differential Ground Speed (when aircraft are in-trail).
(2) Digital Traffic Range.
m. For CAVS installations, the following data should be displayed in the pilot’s primary field of view, but may be displayed in a forward position requiring minimum head and eye movement:
(1) Traffic Identification.
(2) Ownship Ground Speed.
(3) Traffic Ground Speed.
n. For CAVS installations, evaluate the adjustable Range Indication alert function.
o. For CAVS installations, verify that for CAVS designated traffic less than 1.4 NM horizontal range causes a caution alert. Evaluate the visual and aural alert. Note that both ownship and traffic aircraft will need to be “in-air” for this alert to trigger.
3-3. Flight Tests.
a. Flight tests must be conducted for each initial installation of a unique configuration of ADS-B In receiver, position sensor, ASSAP, and CDTI equipment. Flight test data from a different aircraft may be used to establish suitability in follow-on installations. Flight testing must be conducted in the range of an ADS-B Out-equipped aircraft. Flight testing should be conducted within TIS-B and ADS-R coverage. The flight test should verify the following:
(1) The other aircraft flight identification (if implemented).
(2) The ability to select a desired target aircraft (if implemented).
(3) The ability to display ground speed of the selected target aircraft (if implemented).
(4) The bearing from own-ship to the other aircraft.
(5) The distance from own-ship to the other aircraft.
(6) The relative altitude of the other aircraft.
(7) The direction of travel (ground track) of the other aircraft.
(8) The ground speed of the other aircraft (if implemented).
(9) The targets are appropriately displayed during maneuvers throughout the normal flight envelope.
(a) Movement of displayed target information should not result in objectionable jitter, jerkiness, or ratcheting effects.
(b) Movement of displayed target information should not blur, shimmer, or produce unintended dynamic effects such that the information becomes distracting or difficult to interpret.
(c) Filtering or coasting of data intended to smooth the movement of CDTI displayed target information should not introduce significant positioning errors or create system lag that makes it difficult to perform the intended task.
(d) False or redundant tracks should not occur regularly during the flight. This would indicate that the track correlation is not performing properly. This could indicate that the TCAS antenna bearing is performing poorly, as an example.
b. If implemented, verify that the information provided on the CDTI display is suitable for the surface application. Depending upon which surface class has been installed, either runways only will be depicted or both runways and taxiways will be depicted.
c. If ITP is installed, evaluate the ITP functionality. The intent of ITP flight testing is to validate that the equipment functions properly when installed on the aircraft. It is not the intent of the ITP flight test to exhaustively test ITP geometries. Individual ITP scenarios to test each ITP geometry may be performed in a conformed ground simulator environment. The scenarios below were chosen to be representative of key operational ranges at which the equipment operates differently. The TCAS validation functionality in particular is difficult to test adequately on ground or in a laboratory environment. This is due to the challenge of creating an RF simulation that accurately reflects the in-flight environment and aircraft installation effects.
A flight test of ITP should successfully demonstrate the three scenarios below. For each of the scenarios, perform the steps in this paragraph. Verify that the reference traffic is being 20
displayed as a valid reference aircraft for the ITP application. Verify that the reference aircraft is shown on the ADS-B traffic display and any dedicated ITP display. This indicates that the ADS-B surveillance portion of ITP is functioning successfully. Verify that the ITP distance computed agrees with the planned value for the flight profile. The computed value may vary from the planned value due to variations from planned aircraft speeds, range, and position.
Differences should be documented and investigated after the flight for correctness. Enter CPDLC commands for an ITP request using either automatically generated messages or manually through free-text input by the pilot. If automatically generated, verify that the CPDLC text accurately represents the ITP reference aircraft information. If the local air traffic facility is equipped and able to receive the CPDLC message successfully, then exercise the CPDLC link and request an acknowledgement from ATC. If the local air traffic facility is not equipped, then the CPDLC link does not need to be exercised. CPDLC installation guidance is covered in AC 20-140() Guidelines for Design Approval of Aircraft Data Link Communication Systems Supporting Air Traffic Services (ATS). During any or all of the scenarios, alter the position, altitude, or ground speed of the aircraft in order to violate the ITP initiation criteria (refer to Table 3 below). Verify that the ITP equipment indicates that an ITP maneuver is not possible. If implemented, verify that the proper reason is indicated for the ITP maneuver not being available.
(1) Scenario 1 ITP Reference aircraft < 30 NM: Perform a flight test with two aircraft, one being the Ownship aircraft and the other being the Reference aircraft.
Position the aircraft so they are in-trail between 20 and 30 nautical miles and within 15 knots of ground speed. The ITP equipment will use TCAS measurements (range, bearing, and altitude) to validate ADS-B position.
(2) Scenario 2 ITP Reference aircraft > 30 NM: Position the aircraft so they are in-trail greater than 30 nautical miles, but within the capability of the manufacturer’s TCAS to get occasional replies, and within 15 knots of ground speed. The ITP equipment will use TCAS measurements of opportunity (range, bearing, and altitude) to validate ADS-B position when able. At this range, TCAS may not be able to sustain a track due to spotty transponder replies. It is the responsibility of the TCAS manufacturer to provide the approximate maximum range at which TCAS measurements are still available.
(3) Scenario 3 ITP Reference aircraft outside of TCAS range: Position the aircraft so they are on similar tracks (within 45 degrees), outside of the manufacturer provided TCAS measurement range, and within 15 knots of ground speed. In this geometry, TCAS validation will be unavailable.
Table 3. ITP Maneuver Criteria ITP Speed/Distance Criteria ITP Distance >= 15 NM and Closing Ground Speed Differential <= 20 knots or ITP Distance >= 20 NM and Closing Ground Speed Differential <= 30 knots Relative Altitude Criteria Difference in altitude between the ITP and Reference Aircraft is less than or equal to 2000 feet imilar Track Criteria S Difference in track angles between ITP and Reference Aircraft less than +/- 45 degrees osition Accuracy for ITP and P Reference Aircraft ITP and Reference Aircraft data with horizontal position accuracies of at least 0.5 NM (95%) osition Integrity for ITP and P Reference Aircraft ITP and Reference Aircraft data with horizontal position integrity bounds of 1.0 NM @ 1x10E-05 elocity Accuracy for ITP and V Reference Aircraft ITP and Reference Aircraft data with horizontal velocity accuracies of at least 10 m/s (19.4 knots) 95% losing Mach Differential C ATC Crosscheck) ( Closing Mach Differential equal or less than 0.06 Mach
d. If CAVS is installed, evaluate the CAVS functionality. The intent of CAVS flight testing is to validate that the equipment functions properly when installed on the aircraft and is suitable for operational use. Perform at least 5 visual approaches within 5 to 10 miles of a leading aircraft. Evaluate that the required display data (refer to paragraph 3-2 l) is suitable for monitoring while performing a visual approach. During the approach, designate the lead aircraft for CAVS and select an appropriate Range Indication alert value. Verify that the range indication is displayed when closing within the designated range value and evaluate for suitability. The CAVS equipment can and will use TCAS measurements (range, bearing, and altitude) if available to validate ADS-B position.
e. If ATAS is installed, evaluate the ATAS functionality. The intent of ATAS flight testing is to validate that the equipment functions properly when installed on the aircraft. Flight testing of ATAS may include a cooperative aircraft or traffic of opportunity.
(1) Evaluate the visual alerts for suitability.
(2) Evaluate aural messages for acceptable volume and intelligibility during both low and high cockpit noise levels with and without headsets/helmets as appropriate.
(3) Before any cooperative flight tests at any altitude, fly both aircraft in close formation to ensure matched altimetry readouts. These checks should be flown at the speeds and altitudes to be used for the tests.
Appendix A Latency Analysis
1. Purpose.
The purpose of this appendix is to provide guidelines on accomplishing a latency analysis of your ADS-B In system to demonstrate that it complies with the end-to-end budget for ADS-B applications. It is important to minimize latency and the uncertainty of latency (i.e. , how the latency differs between updates) at the system integration level. The easiest way to ensure this design goal is met is to provide a direct connection between the position source and the ADS-B equipment. Any other system blocks between them will increase latency and uncertainty. In some cases, an increase in uncertainty can have a more detrimental effect than the latency itself.
Refer to RTCA/DO-317B, Appendix J for additional information on the interfaces described below.
2. Analysis.
For ADS-B In installations, the latency analysis consists of two parts; the traffic latency analysis and the own-ship position latency analysis. Together, these analyses must show:
a. That the total latency allowance is not exceeded, and
b. The own-ship position and traffic positions are estimated to a time of applicability within 1 second of the time of display.
Note: Manufacturers should ensure installation instructions adequately address latency to assist the installer.
3. Traffic Latency Analysis.
Figure A-1 depicts a block diagram of the ADS-B In system and the recommended latency budget allocated to each block. To demonstrate that the system does not exceed the total latency budget, determine the applicable latencies for each component and total all of the individual component latencies. You must include all sources of latency, including, but not limited to: the ADS-B receiver, the ASSAP equipment, the CDTI equipment, and any intermediary devices. The total for your system between interface D and interface G must not exceed 3.5 seconds. It is acceptable for a manufactur er to allocate the total budget among their system components as needed. However, this design choice will limit the flexibility of pairing their equipment with other manufacturers. In calculating worst case latency, the traffic latency analysis must assume the simultaneous processing of the maximum number of traffic symbols the system is designed to support.
4. Traffic Time of Applicability Analysis.
Demonstrate by analysis that the traffic displayed to the flight crew has been estimated forward to be within 1 second of the time of display. For instance, if the latency analysis in the previous paragraph comes to 2.6 seconds, the traffic will need to be estimated forward 2.6 seconds +/- 1 23