NOTE 1: CAUTION - When the aircraft is on the ground, the Mode S transponder must be inhibited from replying to any Mode A, Mode C, Mode A/C/S all-call interrogations and Mode S-only all-call interrogations.
NOTE 2: This inhibit is usually accomplished via an appropriate transponder pin connected through the weight-on-wheels switch, but it might also be accomplished through some other automatic means (for example, velocity/altitude algorithm, etc.). The inhibit means must be verified during ground testing.
NOTE 3: While on the ground, the transponder normally should stop output of acquisition squitters (short squits), and should continue output of extended squitters (known as long squits or ADS-B) in the surface format, and it should reply to any discretely-addressed aircraft interrogations. This too should be verified during ground testing. The exact conditions for transmission of acquisition squitter are specified in DO-181E section paragraph 2.2.18.2.6, Acquisition Squitter Protocols.
3-4. Basic Flight Tests.
a. During all phases of flight, determine if there is any mutual interference with any other aircraft system. Have all installed systems, including the weather radar, operating during the flight test.
b. Evaluate TCAS II aural messages for acceptable volume and intelligibility during both low and high cockpit noise levels (idle descent at low speed and high power at maximum operating limit speed Vmo) with headset covering outboard ear only (when appropriate) and without headsets. In the case of turbo-prop aircraft where the aircrew utilizes headsets via the aircraft audio distribution panel, the aural messages should hold the same acceptable volume and intelligibility during both low and high cockpit noise levels. If the TCAS II TEST is used to simulate voice announcements, ensure that the audio level is not changed by use of the TEST function.
c. Demonstrate that traffic information remains valid and usable when the aircraft is pitched ±15 degrees and rolled approximately 30 degrees during normal maneuvers by observing area traffic in the traffic advisory display.
d. Evaluate the effective surveillance range of the traffic display, including target azimuth reasonableness and track stability. Use of targets of opportunity or a non-transport category (low speed) aircraft as a target for these tests is permissible.
e. Determine that any configuration discretes (changes in logic or function with aircraft configuration, altitude, or speed) associated with the TCAS II logic, including inhibits of climb RAs, operate properly unless previously demonstrated during ground tests.
f. Perform the additional flight tests in RTCA/DO-185A or RTCA/DO-185B, paragraph
3.4.4 as applicable, unless previously accomplished under TSO-C119b or TSO-C119c/TSO C119d respectively.
g. Evaluate TCAS II for noninterference during coupled autopilot and flight director (FD) approaches to the lowest minimums approved for the aircraft.
h. Before any cooperative flight tests at any altitude involving the TCAS II-equipped aircraft and another aircraft, 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.
i. Evaluate all selectable modes of the TCAS II to determine that they perform their intended function and that the operating mode is clearly and uniquely annunciated.
j. Re-evaluate any previously installed aircraft systems that required changes as a result of the TCAS II installation. (For example, electronic flight instrument system (EFIS), FD, PFD, navigation displays (ND), IVSI, interface etc.)
k. When hybrid surveillance functionality is included, perform the flight tests in RTCA/DO-300 or DO-300A, MOPS for Traffic Alert and Collision Avoidance System II (TCAS II) Hybrid surveillance, dated December 13, 2006 and dated Mar 20, 2013 respectively, paragraph 3, as appropriate unless previously accomplished under TSO-C119c or TSO-C119d.
3-5. Planned Encounter Flight Tests. The objective of these flight tests is to demonstrate adequate TCAS II surveillance and to verify smooth, predictable TCAS II performance. First establish the appropriate safety rules, static system leak test (if necessitated by having opened the system), and altimeter correlation between the encounter aircraft and the TCAS aircraft. The following encounters between the TCAS II aircraft and a dedicated intruder aircraft should be flown to assure that the TCAS II aircraft system performs its intended function by generating TAs and RAs and is consistent with RTCA/DO-185A or RTCA/DO-185B as applicable, and RTCA/DO-300 or RTCA/DO-300A as appropriate. The intruder aircraft must be equipped with a previously approved transponder installation capable of Mode A, Mode C, and for those tests necessary, Mode S, TCAS II and ADS-B Mode S Extended Squitter if appropriate. These tests are also intended to expose the installed TCAS II system to a reasonable number of carefully controlled encounters that are likely to occur in service. This matrix covers the envelope of encounter speeds, altitudes, and geometries that have in the past identified flaws in surveillance, logic, and antenna mechanization that were not detected earlier by bench tests. Fly the following encounters:
a. Intruder overtaking TCAS II aircraft (from the aft quadrants).
b. Head-on.
(1) Low and high closure speeds.
(2) Above climb limit, TCAS II to TCAS II.
(3) TCAS II against Mode C with TCAS II above intruder and above climb limit (intent is to force TCAS II aircraft to descend.)
(4) At 3000 feet over calm water to evaluate multipath protection.
c. Converging.
(1) Crossing (intruder above TCAS II, descending or vice versa.)
(2) Evaluate the TA-only mode during planned encounters.
(3) Evaluate a mix of intruder transponder modes (A, C, S and S with extended squitter) but primary emphasis should be on TCAS II-to-TCAS II coordination, and on Mode C replies from the intruder aircraft.
(4) Evaluate a mix of encounters with TCAS II both above and below the intruder.
(5) If a flight test is necessary to ensure compatibility with other designs, verify correct air-to-air coordination between the test TCAS II and another manufacturer’s previously approved equipment (refer to paragraph 2-15).
(6) Evaluate the effect of electrical transients (bus transfer) during encounters. The TCAS II should not experience adverse effects. No false TAs or RAs should be generated as a result of electrical transients. Normal TCAS II functions and displays should be restored within approximately three seconds.
3-6. Mode S Transponder Tests.
a. This guidance doesn’t cover Mode S Extended Squitter or Mode S Elementary/Enhanced surveillance.
b. The tests described in these paragraphs may be used to obtain the certification of a stand-alone Mode S transponder installation (an installation without TCAS II). These tests should also be used to evaluate a Mode S transponder installed as part of a TCAS II installation.
The tests primarily verify the installed antenna(s) are compatible with the Mode S transponder and provide an adequate response to ground radar interrogations during normal aircraft maneuvers.
c. Additionally, these tests demonstrate that the Mode S transponder functions properly as installed and does not interfere with other aircraft electronic equipment. The need for a detailed flight test is reduced when the Mode S transponder and antenna installation are identical 27
or similar to that of previously approved ATCRBS transponder installation. If a previously installed and certified transponder is being upgraded, all of the guidance in this section is not necessarily required to approve the upgrade. A careful examination of the proposed transponder upgrade should be accomplished to determine which of the tests specified in this section are necessary and appropriate. Typical testing associated with the initial installation and certification of a new transponder may not be necessary when upgrading a previously approved transponder. For example, if a software upgrade is being considered which would add extended squitter functionality to a transponder in a previously approved installation, detailed flights would not be required if appropriate ground testing adequately evaluates the added functionality.
NOTE 1: CAUTION! When conducting flight testing of the transponder or TCAS system, you must prevent being a source of interference to ATC or other TCAS aircraft operating in the area.
For example, using a fixed transponder to simulate an intruder aircraft can cause data to be transmitted which produce false targets for the ground ATC surveillance systems or airborne TCAS aircraft.
These false indications of “intruder aircraft” could result in unnecessary ATC communications and possibly in TCAS induced aircraft maneuvers. Therefore, conduct such testing in coordination with ATC.
NOTE 2: The conduct of this test requires cooperation with ATC radar controllers. Coordination with ATC is important before the flight test for any necessary approval of the flight and agreement with the flight test procedures. During the flight test, communication will be required with the controller monitoring the aircraft and reporting transponder performance data.
d. If the Mode S transponder uses a top mounted antenna in addition to a bottom mounted antenna installed at, or near, the same location used by a previously approved ATCRBS transponder antenna, conduct a comprehensive ground test and evaluation in accordance with Appendix B and perform a functional flight test. The transponder code, altitude reporting and “IDENT” features of the transponder should be exercised during normal maneuvering. There should be no objectionable behavior observed by the ATC controller.
e. If a Mode S transponder is installed in an aircraft which does not have a previously approved ATCRBS transponder installation, or that uses a bottom mounted antenna location which differs significantly from that used by a previously approved ATCRBS transponder antenna, conduct the following ground and flight tests:
NOTE: References to the radar facility are references to the radar that provides the data used by the ATC controller(s) during the flight test for monitoring the aircraft and reporting transponder performance data. These are not references to the ATC facility with the radar displays used by the controllers.
(1) Conduct ground tests and evaluations per Appendix B.
(2) Climb and Distance Coverage. Begin at a distance of at least 10 nautical miles (NM) from, and an altitude of 2000 to 3000 feet above the radar facility and using a transponder code assigned by ATC, fly on a heading that will pass the aircraft over the radar facility. At a distance of 5 to 10 NM beyond the radar facility, fly the aircraft at its normal maximum climb attitude to within 90 percent of the certificated altitude for the aircraft, maintaining the aircraft heading within 5 degrees of the track from the radar facility. After reaching the maximum altitude for which the aircraft is certificated, fly level at the maximum altitude to 160 NM for turbojet and some turboprop powered airplanes (or 80 NM for most other aircraft) from the radar facility. (Distance from the radar facility is a function of the airplane’s maximum certificated altitude.) Communicate with the ATC controller for evidence of transponder dropout. During the flight, check the “IDENT” mode of the ATC transponder to assure that it is performing its intended function. There should be no unexpected dropouts (no return for two or more sweeps).
Uncontrollable ringing that hinders use of the ground radar is unsatisfactory.
(3) Long Range Reception. At 90 percent of maximum certificated altitude, perform left and right 360-degree turns, at bank angles of 8 to 10 degrees. The aircraft should be at least 160 (or 80) NM from the radar facility. During these turns, request that the ATC controller monitor the radar displays. There should be no dropouts (no return for two or more sweeps).
(4) High Angle Reception. Perform two 360-degree turns, one to the right and one to the left, at bank angles of 8 to 10 degrees with the airplane at a distance of 50 to 70 NM from the radar facility and at an altitude of at least 35,000 feet or within 90 percent of the maximum altitude for which the aircraft is certificated. There should be no dropouts (no return for two or more sweeps). Switch the transponder to a new code assigned by the ATC controller. The aircraft secondary return on the ATC controller’s radar display should indicate a Mode A code change.
(5) High Altitude Cruise. Within 90 percent of the aircraft’s maximum certificated altitude or its maximum operating altitude beginning at a point 160 (or 80) NM from the radar facility, fly on a course that will pass over the radar facility. The ATC controller should report no unexpected transponder dropout or “ring around.”
(6) Surveillance Approach. Beginning at or above 90 percent of the certificated maximum altitude for the aircraft, perform a letdown and approach to a runway of an airport served by Airport Surveillance Radar (ASR) having an ATCRBS facility. Make the approach at the maximum normal rate of descent. Normal approach and landing configuration for the aircraft should continue down to an altitude of 200 feet or less above the ground radar antenna elevation. Not more than one dropout should occur for any 10 sweeps during final approach.
Uncontrolled ringing that hinders use of the ground radar is unsatisfactory.
(7) Holding and Orbiting Patterns.
(a) At an altitude of 2000 feet above the radar antenna or minimum obstruction clearance altitude (whichever is greater) with landing flaps and gear extended, fly left and right 29
360-degree turns approximately 10 miles from the radar facility. There should be no signal dropouts.
(b) At an altitude of 2000 feet above the radar antenna or minimum obstruction clearance altitude (whichever is greater), fly 45 degree sectors of left and right 10 mile orbital patterns around a radar facility with gear and landing flaps extended. There should be no signal dropouts.
(8) Altitude Reporting. Conduct a functional test of the altitude encoder by comparison with ATC displayed altitudes. Verify correspondence at several altitudes between ATC readings and the Captain’s altimeter, when set at or corrected to 29.92 inches of mercury (or equivalent).
Chapter 4. Follow-on Approvals (STCs or Amended STC or Amended TC).
4-1. The Need for Tests and a Plan.
a. Provide a test plan including adequate aircraft ground testing and evaluations to verify that the design and installation performs its intended function when installed in a different aircraft type under the expected operating conditions. There should be no adverse interactions between the TCAS II or Mode S transponder and existing aircraft systems, and prior approvals of present aircraft equipment should not be compromised. This test plan will generally require a combination of ground tests, basic flight tests, and flight tests involving planned encounters with a Mode C equipped aircraft, or the use of a suitably located fixed transponder. The test plan should contain, as a minimum, the elements of paragraph 3-6 and those covered in the next paragraphs.
b. Flight-testing of TCAS II or Mode S transponder systems for follow-on approvals (previously approved TCAS II or Mode S transponder equipment installed in a different aircraft type) may need to be conducted to verify that the design and installation performs its intended function under the expected operating conditions. Determine that there are no adverse interactions between the TCAS II or Mode S transponder and existing aircraft systems, and that prior approvals of present aircraft equipment have not been compromised.
NOTE: CAUTION! When flight testing the transponder or TCAS system, you must prevent being a source of interference to ATC or other TCAS aircraft operating in the area. For example, using a fixed transponder to simulate an intruder aircraft can cause data to be transmitted which produce false targets for the ground ATC surveillance systems or airborne TCAS aircraft. False indications of “intruder aircraft” could result in unnecessary ATC communications and possibly in TCAS induced aircraft maneuvers. Conduct such testing in coordination with ATC.
4-2. Ground Tests and Evaluations.
a. Evaluate the general arrangement and operation of controls, displays, circuit breakers, annunciators, and placards of the TCAS II system. Conduct a human factors evaluation of the controls, displays and annunciators. Evaluate the TCAS controls and the controls of installed systems that interact with TCAS (for example, transponders) to determine that they are designed and located to prevent inadvertent actuation. Evaluate TCAS displays and annunciations to determine that they support flight crew awareness of TCAS status changes which could result from TCAS mode selections, intentional pilot actuation of other installed systems, or inadvertent pilot actions with TCAS or other installed systems. Evaluate TCAS displays to ensure all information is, at a minimum, legible, unambiguous, and attention-getting (as applicable). In particular, where transponder functions are integrated with other system controls, ensure that unintended transponder mode switching, especially switching to STANDBY or OFF, is not 31
possible. 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).
b. Evaluate the TCAS II self-test features and failure mode displays and annunciators.
c. Verify that the pressure altitude source and radio altimeter are properly interfaced with the TCAS II equipment.
d. Measure the performance of the directional antenna for 360 degrees coverage at 30 degree intervals, as specified under basic ground tests, paragraph 3-3.a.
e. Evaluate the TCAS II system installation for satisfactory identification, accessibility, and visibility during both day and night conditions.
f. Determine that any configuration discretes (changes in logic or function with aircraft configuration, altitude, or speed) associated with the TCAS II logic, including inhibits of climb RAs, operate properly.
g. Verify that the ICAO 24-bit aircraft address and maximum airspeed are correct.
Verify that the transponder and data sources meet the requirements of the failure condition classifications associated with the features.
h. Verify that the windshear and GPWS/TAWS warnings and TCAS II voice alerts are compatible. Also, verify that windshear and GPWS/TAWS warnings can be clearly understood and that TCAS II is automatically switched to the TA Only mode when TCAS II and windshear voice or GPWS/TAWS announcements simultaneously occur. The alert priorities should be windshear, GPWS/TAWS, and then TCAS II.
i. If connected, verify that the altitude alerter is providing correct data to TCAS and that the TCAS II logic correctly weakens or strengthens the displayed RA using the altitude alerter input.
j. Verify that the air/ground inputs are connected properly.
NOTE 1: CAUTION! When the aircraft is on the ground, the Mode S transponder must be inhibited from replying to any Mode A, Mode C, Mode A/C/S all-call interrogations and Mode S-only all-call interrogations.
NOTE 2: This inhibit is usually accomplished via an appropriate transponder pin connected through the weight-on-wheels switch, but it might also be accomplished through some other automatic means (for example, velocity/altitude algorithm, etc.). The inhibit means must be verified during ground testing.
NOTE 3: While on the ground the transponder normally should stop output of acquisition squitters (short squits), and should continue output of extended squitters (known as long squits or ADS-B) in the surface format and it should reply to any discretely addressed aircraft interrogations. This too should be verified during ground testing. The exact conditions for transmission of acquisition squitter are specified in DO-181E, paragraph 2.2.18.2.6, Acquisition Squitter Protocols.
4-3. Flight Tests.
a. The certification policy for follow-on approvals (STC or amended STC) of TCAS II V7.0 or V7.1 units is that flight tests may not be required, if the appropriate testing is performed on the ground to certify that the V7.0 or V7.1 unit was correctly installed and that any new interfaces operate correctly with the TCAS II logic.
b. If we determine that certification flight-testing is required, demonstrate the following:
(1) Verify proper operation of the traffic display by observing proximate traffic, at least one TA and at least one RA. Confirm that the appropriate aural alerts occur correctly with the TA and RA. The advisories may be generated by:
(a) Planned encounters with an intruder aircraft operating a transponder with Mode C capability.
NOTE: Before any cooperative flight tests at any altitude involving the TCAS II equipped aircraft and another aircraft, fly both aircraft in close formation to assure matched altimetry readouts. These checks should be flown at the speeds and altitudes to be used for the tests.
(b) Encounters with an operating Mode C transponder installed at a fixed ground location, which reports an appropriate test altitude.
NOTE: CAUTION! When flight testing the transponder or TCAS system, you must prevent being a source of interference to ATC or other TCAS aircraft operating in the area. For example, using a fixed transponder to simulate an intruder aircraft can cause data to be transmitted which produce false targets for the ground ATC surveillance systems or airborne TCAS aircraft. These false indications of “intruder aircraft” could result in unnecessary ATC communications and possibly in TCAS induced aircraft maneuvers.
Conduct such testing in coordination with ATC.
(c) Encounters with aircraft targets of opportunity.
(d) The use of suitable test equipment during ground tests.
NOTE: CAUTION! When ground testing the transponder or TCAS system, you must prevent being a source of interference to ATC or other TCAS aircraft operating in the area. Ground maintenance checks or ramp testing (such as altimetry or bearing accuracy testing) can cause data to be transmitted which produce false targets for the ground ATC surveillance systems or airborne TCAS aircraft. These false indications of “intruder aircraft” could result in unnecessary ATC communications and possibly in TCAS induced aircraft maneuvers. Conduct such testing in coordination with ATC and use antenna shielding (transmission absorption covers or caps) to prevent test data that could generate false intruder information from being transmitted. Using high-powered, hangarmounted transponders to conduct ramp testing is not an acceptable means to test either transponder ramp or TCAS.
(2) During all phases of flight, determine if there is any mutual interference with any other aircraft system.
(3) Evaluate TCAS II aural messages for acceptable volume and intelligibility during both low and high cockpit noise levels (idle descent at low speed and high power at Vmo) with and without headsets, covering the outboard ear where appropriate. In turbo-prop aircraft where the aircrew uses headsets via the aircraft audio distribution panel, the aural messages should hold the same acceptable volume and intelligibility during both low and high cockpit noise levels. If the TCAS II TEST is used to simulate voice announcements, ensure that the audio level is not changed by use of the TEST function.
(4) Evaluate the effective surveillance range of the traffic display, including target azimuth reasonableness and track stability. You may use a non-transport (low speed) Mode C equipped aircraft as a target or a fixed transponder or suitable test equipment for these tests.
NOTE: CAUTION! When flight testing the transponder or TCAS system, you must prevent being a source of interference to ATC or other TCAS aircraft operating in the area. For example, using a fixed transponder to simulate an intruder aircraft can cause data to be transmitted which produce false targets for the ground ATC surveillance systems or airborne TCAS aircraft. These false indications of “intruder aircraft” could result in unnecessary ATC communications and possibly in TCAS induced aircraft maneuvers.
Conduct such testing in coordination with ATC.
(5) Evaluate the Mode S transponder air-to-ground ATCRBS function against an appropriate ground facility.
(6) Determine that any configuration discretes associated with the TCAS II logic, including inhibits of aural annunciations and RAs, operate properly unless previously 34
demonstrated during ground tests. (These include changes in logic or function with aircraft configuration, altitude, or speed.)
(7) Evaluate TCAS II for noninterference during coupled autopilot and flight director approaches to the lowest minimums approved for the aircraft.
(8) Evaluate all selectable modes of the TCAS II to determine that they perform their intended function.
(9) Reevaluate any previously installed aircraft systems that have required changes as a result of the TCAS II installation (such as CMC, EFIS, EICAS FD, PFD, ND, IVSI, and interface).
4-4. Upgrading an Ex isting TCAS II Installation. If you are upgrading an existing approved TCAS II installation to a higher TCAS II version (i.e., V7.0 or V7.1), and the higher version installation is only a software change, then no additional certification flight tests are required to obtain a follow-on STC or amended STC or an amended TC. The appropriate aircraft ground tests of paragraph 4-2 are considered sufficient to ensure that the higher version TCAS II software is operating properly. However, if the upgrade to a higher version TCAS II unit involves changes other than a software change (such as the addition of new interfaces), flight tests in accordance with paragraph 4-3b may be required.
Chapter 5. Airplane Flight Manual Supplement.
5-1. Contents of an A FMS. The AFMS should provide the appropriate system limitations and procedures, and a comprehensive description of all normal modes of operation, including expected flight crew actions.
5-2. TCAS V7.1 AFMS Example. Refer to Appendix A for an example of the elements and extent of detail that may be shown by a typical AFMS (specific performance data, inhibits and procedures may vary with system design and aircraft type).