3-7 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 transmission of data 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: The conduct of this test requires cooperation with ATC 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, the test crew will need to communicate with the controller monitoring the aircraft and reporting transponder performance data.
3.2.4.4 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. The ATC controller should not observe any objectionable behavior.
3.2.4.5 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. In other words, these refer to where the radar antenna/interrogator is located, not the displays used by the controllers.
3.2.4.6 Conduct ground tests and evaluations per Appendix B.
3.2.4.7 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. 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
3-8 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 to check 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.
3.2.4.8 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).
3.2.4.9 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.
3.2.4.10 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.”
3.2.4.11 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
3-9 approach. Uncontrolled ringing that hinders use of the ground radar is unsatisfactory.
3.2.4.12 Holding and Orbiting Patterns.
3.2.4.12.1 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 360-degree turns approximately 10 miles from the radar facility. There should be no signal dropouts.
3.2.4.12.2 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.
3.2.4.13 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).
3.2.4.14 Verify that a transponder failure and transponder in the standby mode are properly annunciated in accordance with sections 2.2.10 of this AC.
4-1 CHAPTER 4. FOLLOW-ON APPROVALS (STCs or Amended STC or Amended TC) - The Need for Tests and a Plan.
This section provides guidance for follow-on approvals of TCAS and Mode S transponders.
4.1 General
4.1.1 Provide a test plan including adequate aircraft ground testing and evaluations to verify that the design and installation performs its intended function when you install it 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 the installation should not compromise prior approvals of present aircraft equipment. 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 3.2.1.3 and 3.2.4 and those in the next paragraphs.
4.1.2 You may need to conduct 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 or change to the defined configuration of a previously approved system installation) 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 the installation does not compromise prior approvals of present aircraft equipment.
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 transmission of data 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.
4.2.1 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 the control design and location prevents 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,
4-2 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 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).
4.2.2 Evaluate the TCAS II self-test features and failure mode displays and annunciators.
For forward fit or new installations (as defined in the note to section 2.2.10), verify that a TCAS failure and TCAS in the standby mode are properly annunciated in accordance with sections 2.2.10 of this AC.
4.2.3 Verify proper interface of the pressure altitude source and radio altimeter with the TCAS II equipment.
4.2.4 Measure the performance of the directional antenna for 360 degrees coverage at 30 degree intervals, as specified under basic ground tests, paragraph 3.2.1.1.
4.2.5 Evaluate the TCAS II system installation for satisfactory identification, accessibility, and visibility during both day and night conditions.
4.2.6 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.
4.2.7 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.
4.2.8 Verify that the windshear and GPWS/TAWS warnings and TCAS II voice alerts are compatible. Also, verify that the flight crew can clearly understand windshear and GPWS/TAWS warnings and that TCAS II automatically switches 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.
4.2.9 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.
4.2.10 Verify proper connection of the air/ground inputs.
CAUTION: When the aircraft is on the ground, the system must inhibit the Mode S transponder from replying to any Mode A, Mode C, Mode A/C/S all-call interrogations and Mode S-only all-call interrogations.
Note 1: You can usually implement this inhibit via an appropriate transponder pin connected through the weight-on-wheels switch, but you might also implement it
4-3 through some other automatic means (for example, velocity/altitude algorithm, etc.).
You must verify the inhibit implementation during ground testing.
Note 2: 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. You should also verify this during ground testing. DO-181E, paragraph 2.2.18.2.6, Acquisition Squitter Protocols, specifies the exact conditions for transmission of acquisition squitter.
4.2.11 For forward fit or new installations (as defined in the note to section 2.2.10), verify that a transponder failure and transponder in the standby mode are properly annunciated in accordance with sections 2.2.10 of this AC.
4.3 Flight Tests.
4.3.1 The certification policy for follow-on approvals (STC or amended STC) of TCAS II V7.0 or V7.1 units is that you may not need to do flight tests, if you perform the appropriate testing on the ground to certify that you correctly installed the V7.0 or V7.1 unit and that any new interfaces operate correctly with the TCAS II logic.
4.3.2 If we determine that you need to do certification flight-testing, demonstrate the following:
4.3.2.1 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. You may generate the advisories by:
4.3.2.1.1 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. You should fly these checks at the speeds and altitudes you will use for the tests.
4.3.2.1.2 Encounters with an operating Mode C transponder installed at a fixed ground location, which reports an appropriate test altitude.
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 transmission of data 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.
4-4
4.3.2.1.3 Encounters with aircraft targets of opportunity.
4.3.2.1.4 The use of suitable test equipment during ground tests.
CAUTION: When ground testing the transponder or TCAS system, you must take precautions to 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 transmission of data 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 the system from transmitting test data that could generate false intruder information. Using high-powered, hangar-mounted transponders to conduct ramp testing is not an acceptable means to test either transponder or TCAS. As an alternative to the use of antenna shielding, radiated testing can be used provided that a) if in Air Mode, the Mode C code, Mode S altitude reporting downlink formats, and ADS-B altitude reports all respond with an altitude that is at least 600 feet below ground level or an altitude above 90,000 feet above ground level, and b) if aircraft is in a normal pre-dispatch configuration (in On Ground Mode and transponder set to "TRANSPONDER" mode), the Mode C code, Mode S altitude reporting downlink formats, and ADS-B altitude reports all respond with an altitude at ground level.
4.3.2.2 During all phases of flight, determine if there is any mutual interference with any other aircraft system.
4.3.2.3 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 use of the TEST function does not change the audio level.
4.3.3 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.
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 transmission of data which produce false targets for the ground ATC surveillance
4-5 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.
4.3.4 Evaluate the Mode S transponder air-to-ground ATCRBS function against an appropriate ground facility.
4.3.5 Determine that any configuration discretes associated with the TCAS II logic, including inhibits of aural annunciations and RAs, operate properly unless you previously demonstrated this during ground tests. (These include changes in logic or function with aircraft configuration, altitude, or speed.)
4.3.6 Evaluate TCAS II for noninterference during coupled autopilot and flight director approaches to the lowest minimums approved for the aircraft.
4.3.7 Evaluate all selectable modes of the TCAS II to determine that they perform their intended function.
4.3.8 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 Existing 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 you don’t need to do any additional certification flight tests to obtain a follow-on STC or amended STC or an amended TC. The appropriate aircraft ground tests of paragraph 4.2 are 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), you may need to do flight tests in accordance with paragraph 4.3.2.
4.5 Upgrading an Existing Mode S Transponder Installation As stated in Section 3.2.4.3, typical testing associated with the initial installation and certification of a new transponder may not be necessary when upgrading a previously approved transponder. Examination of the proposed transponder upgrade should be accomplished to determine which tests are necessary and appropriate. For example, when upgrading an existing approved Mode S transponder installation to add ADS-B Out functionality and the upgrade is only a software change, if ground testing adequately evaluates the added functionality, then no additional certification flight tests are required to support a follow-on STC, amended STC, or amended TC.
5-1 CHAPTER 5. AIRPLANE FLIGHT MANUAL SUPPLEMENT
5.1 Content of an AFMS.
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 0 for an example of the elements and extent of detail that a typical AFMS may show (specific performance data, inhibits and procedures may vary with system design and aircraft type).
Appendix A A-1 APPENDIX A. EXAMPLE TCAS II V7.1 AFMS INTRODUCTION.
You may, when appropriate, replace descriptive material and procedures in this Airplane Flight Manual Supplement (AFMS) example by reference in the AFMS to the TCAS II equipment supplier’s pilot operating guide. However, the AFMS reference to this guide must specify date and revision level; and not be open ended, such as, “or later revision,” unless the pilot’s guide is specifically FAA approved. Also, the AFMS must define the specific configuration approved from the various options contained in the pilot’s guide; for example, which model control panel, whether the pilot initiated self-test is available in flight, range features, TA vertical display features, and so forth.
-EXAMPLE-
AIRPLANE FLIGHT MANUAL SUPPLEMENT (Example for an aircraft equipped with IVSI/RA displays) DESCRIPTION.
The TCAS II is an on-board collision avoidance and traffic situation display system with computer processing to identify and display intruding and threatening collision aircraft, and issue resolution advisories in the form of vertical maneuver guidance on the pilot and copilot’s instantaneous vertical speed indicators (IVSI). From the transponder replies, TCAS II determines relative altitude, range, and bearing of any ATCRBS or Mode S equipped aircraft with altitude reporting. From this, TCAS II will determine the level of advisory using standardized algorithms. The TCAS II will resolve multiple aircraft encounters. ATCRBS equipped aircraft that only reply with Mode A information will not provide altitude information;
therefore, TCAS II will not issue resolution advisories for these aircraft but can issue traffic advisories. The TCAS II will not detect aircraft that are not equipped with transponders.
The TCAS II installation consists of one TCAS II processor, one top mounted directional antenna, one bottom mounted blade (or directional antenna), one Mode S transponder with control panel and top and bottom antennas, one traffic advisory display with control panel (if not combined with the IVSI/RA indicators), two resolution advisory displays, one overhead speaker for voice messages, (caution/warning lights), and associated wiring.
The TCAS II provides two levels of advisories:
1. If the traffic gets within 25 to 48 seconds, depending upon altitude, of projected Closest Point of Approach (CPA), TCAS II then considers it an intruder, and issues an aural and visual traffic advisory (TA). This level calls attention to what may develop into a collision threat using the TA display and the voice message, “TRAFFIC - TRAFFIC.” It permits mental and physical preparation for a possible maneuver to follow and assists the pilot in achieving visual acquisition of the intruding aircraft.
Appendix A A-2
2. If the intruder gets within 15 to 35 seconds, depending upon altitude, of CPA, TCAS II then considers it a threat, and issues an aural and visual resolution advisory (RA). This level provides a recommended vertical maneuver using modified IVSIs and voice messages to provide adequate vertical separation from the threat aircraft or prevents initiation of a maneuver that would place the TCAS II aircraft in jeopardy. TCAS II is a backup system to the “SEE AND AVOID” concept and ATC surveillance. TCAS II annunciates RAs by the following voice messages, as appropriate, along with the expected pilot response:
(1) “CLIMB, CLIMB”--climb at the rate depicted by the green (fly to) arc on the IVSI, nominally between 1,500 and 2,000 fpm.
(2) “DESCEND, DESCEND”--descend at the rate depicted by the green (fly to) arc on the IVSI, nominally between 1,500 and 2,000 fpm.
(3) “MONITOR VERTICAL SPEED”--ensure that vertical speed is out of the illuminated IVSI red arc until the RA is completed.
(4) “LEVEL OFF, LEVEL OFF” -- reduce vertical speed to zero feet per minute. A green arc will appear, beginning at zero feet per minute. The system can issue this as the initial RA or as a subsequent RA.
(5) “CLEAR OF CONFLICT”--range is increasing, and separation is adequate.
Expeditiously return to the applicable ATC clearance, unless ATC directs otherwise.
(6) “CLIMB, CROSSING CLIMB, CLIMB, CROSSING CLIMB”--climb at the rate depicted by the green (fly to) arc on the IVSI, nominally between 1,500 and 2,000 fpm. You will best achieve safe separation by climbing through the threat’s flight path.
(7) “DESCEND, CROSSING DESCEND, DESCEND, CROSSING DESCEND”-- descend at the rate depicted by the green (fly to) arc on the IVSI, nominally between 1,500 and 2,000 fpm. You will best achieve safe separation by descending through the intruder’s flight path.
(8) “MAINTAIN VERTICAL SPEED, MAINTAIN”--continue the existing climb or descent rate, or other vertical speed, as depicted by the green (fly to) arc on the IVSI. You will best achieve safe separation by not altering the existing vertical speed.
(9) “MAINTAIN VERTICAL SPEED, CROSSING MAINTAIN”--continue the existing climb or descent rate, or other vertical speed, as depicted by the green (fly to) arc on the IVSI. You will best achieve safe separation by not altering the existing vertical speed and climbing or descending through the threat’s flight path.
Appendix A A-3 The following voice messages annunciate enhanced TCAS II maneuvers when initial RA does not provide sufficient vertical separation. The tone and inflection indicate increased urgency.
(1) “INCREASE CLIMB, INCREASE CLIMB”--climb at the rate depicted by the green (fly-to) arc on the IVSI, nominally between 2,500 and 3,000 fpm. Received after “CLIMB” advisory, and indicates you need to climb faster to achieve safe vertical separation from a maneuvering aircraft.
(2) “INCREASE DESCENT, INCREASE DESCENT”--descend at the rate depicted by the green (fly-to) arc on the IVSI, nominally between 2,500 and 3,000 fpm. Received after “DESCEND” advisory, and indicates you need to descend faster to achieve safe vertical separation from a maneuvering aircraft.
(3) “CLIMB – CLIMB NOW, CLIMB – CLIMB NOW”--climb at the rate depicted by the green (fly-to) arc on the IVSI, nominally between 1,500 and 2,000 fpm. Received after a “DESCEND” resolution advisory and indicates you need to reverse your vertical direction to achieve safe vertical separation from a maneuvering threat aircraft.
(4) “DESCEND – DESCEND NOW, DESCEND – DESCEND NOW”-descend at the rate depicted by the green (fly-to) arc on the IVSI, nominally between 1,500 and 2,000 fpm.
Received after a “CLIMB” resolution advisory and indicates you need to reverse your vertical direction to achieve safe vertical separation from a maneuvering threat aircraft.