(F) Extended Altitude Surveillance Switch. A switch may be provided to select the viewing of traffic from 2700 feet below own aircraft to a maximum of 9900 feet above own aircraft and the viewing of traffic from 2700 if to a na num of 900 feet above own aircraft to a maximum of 9900 feet below own aircraft.
(9) Resolution Display.
to prevent a maneuver that would significantly reduce the vertical separation Hon to regif the reut we worth at sopration between ownship and a threat aircraft.
(ii) Description. The resolution display may be integrated with the two primary IVSIs on the flightdeck. These displays depict red arcs along the perimeter of round dial IVSIs or red vertical lines on vertical tape IVSIs that must be avoided in order to maintain safe vertical separation.
pilot's task is to maneuver the aircraft promptly to achieve a vertical speed just out of the illuminated red arc or line (within the green "fly to" arc or line) when presented or to maintain a vertical speed out of the illuminated red arc or line that most nearly complies with the ATC clearance.
(iii) Symbology. The resolution display must depict a red illuminated arc or line for corrective RAs. Corrective RAs should also depict a green "fly to" symbol; for example, when a climb RA is issued on a round dial IVSI, a red colored arc should be depicted (adjacent to the IVSI scale) from -6000 FPM to +1500 FPM and a green fly-to arc or line from +1500 FPM to approximately 2000 FPM. The resolution display must also depict an illuminated arc to be avoided for preventive RAs. A green "fly to" arc or line is not required in this case since the current aircraft vertical speed is satisfactory. The color of the preventive RA arc or line should be red. The same requirements for round dial RA displays are applicable to vertical tape RA displays in PFD's. Some applicants may wish to integrate the RA display within an EADI or PFD. There are several good reasons to pursue the development of this technology within PFD's and EADI's. The basic concepts of a warning area and a "fly to" area must be retained. The use of new TCAS symbology such as target pitch attitudes or flight path angles will require testing throughout the flight envelope to determine accuracy, over/undershoot tendencies, flight technical error, and potential confusion with flight director symbology. Applicants pursuing this technology should contact the appropriate FAA ACO early in the development cycle.
(iv) Failure indications must be provided for TCAS failures (TCAS unable to generate RAs). Annunciation must be provided for the TA only mode.
Electrical IVSI failures must also be annunciated.
(10) Caution/Warning Lights.
(i) Discrete caution and/or warning lights may be installed which are separate from the traffic display. The purpose of these additional indicators is to annunciate the presence of potentially threatening intruder aircraft at times when the pilot's attention may be diverted from the primary TCAS display. Two different discrete TCAS II annunciators have been used:
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(A) A discrete amber caution annunciator which indicates the presence of a TCAS II TA. Installation of this discrete caution annunciator is optional. If installed, it must be located in each pilot's primary field of view and be inhibited below 400 feet AGL.
(B) A discrete red warning annunciator which indicates the So this discrete varming maneton
(ii) Because of the numerous TCAS Il advisories expected in service, the basic aircraft master caution and warning system should not be interfaced with these TCAS II caution/warning discretes. Overuse of the primary aircraft caution and warning system would tend to reduce its effectiveness in annunciating non-TCAS II system failures.
(iii) Discrete visual alerts should remain on until cancelled by the pilot or until the aircraft is no longer considered an intruder or a threat by TCAS II.
(11) Aural Alerts.
(i) Each TCAS II aural alert should be annunciated by a dedicated voice message over a cockpit speaker at a volume adequate for clear understanding at high cockpit noise levels, but not excessively loud at low noise levels. The evaluation includes the case where a flight crewmember is wearing a headset, covering the outboard ear when appropriate.
by the voice message "TRAFFIC, TRAFFIC" stated once for each TA. (ii) The TCAS II Traffic Advisories (TAs) should be annunciated
(iii) The TCAS II Resolution Advisories (RAs) should be annunciated by the following voice messages, as appropriate:
(A) "CLIMB, CLIMB, CLIMB" (Climb at the rate depicted by the green (fly to) arc or line on the IVSI or other suitable indicator.)
(B) "DESCEND, DESCEND, DESCEND" (Descend at the rate depicted by the green (fly to) arc or line on the IVSI or other suitable indicator.)
(C) "MONITOR VERTICAL SPEED-MONITOR VERTICAL SPEED" (Spoken only once if softening from a previous corrective advisory.) Assure that vertical speed is out of the illuminated IVSI red arc or line.
(D) "REDUCE CLIMB-REDUCE CLIMB" (Reduce vertical speed to a value within the illuminated green arc or line.)
(E) "CLEAR OF CONFLICT" (Range is increasing, and separation is adequate; expeditiously return to the applicable clearance, unless otherwise directed by ATC.)
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(F) "CLIMB, CROSSING CLIMB, CLIMB, CROSSING CLIMB" (Climb at the rate depicted by the green (fly to) arc or line on the IVSI or other suitable indicator.) Safe separation will best be achieved by climbing through the threat's flight path.
(G) "REDUCE DESCENT-REDUCE DESCENT" (Reduce vertical speed to a value within the illuminated green arc or line.)
(H) "DESCEND, CROSSING DESCEND, DESCEND, CROSSING DESCEND" Descend at the rate depicted by the green (fly to) arc or line on the IVSI or other suitable indicator.) Safe separation will best be achieved by descending through the threat's flight path.
(iv) The following voice messages are required to annunciate enhanced TCAS II maneuvers when the initial RA does not provide sufficient vertical separation. The tone and inflection must connote increased urgency.
(A) "INCREASE CLIMB, INCREASE CLIMB" (Climb at the rate depicted by the green (fly to) arc or line on the ISI or other suitable indicator.) Received after "CLIMB" advisory, and indicates an additional climb rate is required to achieve safe vertical separation from a maneuvering threat aircraft.
(B) "INCREASE DESCENT, INCREASE DESCENT" (Descend at the rate depicted by the green (fly to) arc or line on the IVSI or other suitable indicator.) Received after "DESCEND" advisory, and indicates additional descent rate is required to achieve safe vertical separation from a maneuvering threat aircraft.
rate depicted by the green (fly to) arc or line on the IVSI or other suitable indicator). Received after a "DESCEND" resolution advisory and indicates a reversal in sense is required to achieve safe vertical separation from a
• depicted ace van after (D) "DESCEND - DESCEND NOW, DESCEND - DESCEND NOW" (Descend at the rate depicted by the green (fly to) arc or line on the IVSI or other suitable indicator.) Received after a "CLIMB" resolution advisory and indicates a reversal in sense is required to achieve safe vertical separation from a maneuvering threat aircraft.
(v) All TCAS 1I aural alerts must be inhibited below 400 feet AGL.
(vi) Both increases and decreases in the threat level must be aurally annunciated. However decreases in threat level need only be annunciated once, e.g., a "monitor vertical speed" aural which follows a climb RA should only be annunciated once.
(vil) in general, other messages which are clear and unambiguous will be evaluated on an individual basis. Messages which use negatives should not be used (e.g., "DON'T CLIMB").
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Software Verification and Validation. The verification and validation of TCAS II software using the procedures outlined below are required for the first installation of a manufacturer's TCAS II equipment. These procedures shall also be applied to subsequent software changes to a manufacturer's TCAS II equipment. A manufacturer may provide a design that partitions the software which affects resolution advisories from other software (level 3) such as that necessary for the traffic display. If the partitioned software is initially approved by the FAA, verification and validation for the level 3 software may be accomplished by the TCAS II manufacturer using the minor change authority of the TSO system.
(1) The verification and validation of the TCAS II software represents a unique challenge because the collision avoidance algorithms, commonly called "CAS Togic," as contained in Volume II of RTCA document DO-185, represent a software design specification. However, the surveillance software necessary to establish and maintain the relative tracks of nearby transponder equipped aircraft and the software necessary to provide the interface with the Mode S transponder and with other aircraft sensors and displays must be developed by the manufacturer of the TCAS II equipment. This hybrid approach to the specification of the software requirements and design does not permit the direct application of the software criteria contained in RTCA document DO-178A. The CAS logic has been provided by Volume II of RTCA document
(2) If software is used for the displays of TCAS II resolution advisories or in the operation of the Mode S transponder data link, the verification and validation of this software should be done to level 2, as defined in RTCA document DO-178A. These procedures should also be applied where the TCAS II manufacturer develops the software requirements for the TCAS II processor associated with functions other than surveillance or the CAS Where the software design is specified by Volume II of RTCA document DO-185, the manufacturer of the TCAS II processor should conduct code walk-throughs and develop and perform module tests and module integration tests to verify that the specified software design has been implemented correctly. This includes the surveillance software necessary to establish and maintain the relative tracks of nearby transponder equipped aircraft.
(3) The functional tests required by TSO C-119a as described in Volume I of RTCA document DO-185, do not provide complete testing for the TCAS II processor software. The TCAS II manufacturer must develop additional functional tests which correspond to the detailed requirements which it develops for the TCAS II processor. The potential consequences of software errors in the TCAS II processor or resolution display require that the manufacturer provide a structural coverage analysis to show single condition test coverage of all instructions at the source code which can affect the generation and display of resolution advisories. The tests which provide this may be a combination of module tests, module integration tests and functional Par 3 19
AC 20-131A 3/29/93
(4) Equipment produced in accordance with a technical standard order may have obtained FAA concurrence that the software for the equipment was produced in accordance with the criteria of RTCA document DO-178A for a particular sottware level. Nevertheless, it is the responsibility of the applicant who first installs a manufacturer's TAS II equipment in an aircraft to demonstrate to the appropriate FAA ACO that the system software used for the TCAS II equipment, Mode S transponder and new sensors and displays necessary to provide resolution advisories have been developed in accordance with the criteria outlined above. Data from the TSO process may be sufficient to establish that the appropriate verification and validation have been accomplished, but the ACO may require additional tests and analysis of the software for the installed TCAS II system. Subsequent installations of the same TCAS II equipment on other aircraft types do not require any additional verification if the software is not changed.
System Safety Analyses. A false resolution advisory has the potential of causing a mid-air collision. Failures of the TCAS Il equipment and its associated sensors and displays which could provide a false resolution advisory must be improbable. This should be established using the methods described in AC 25.1309-1A, System Design and Analysis. It is expected that a failure modes and effects analysis (FMEA) and a quantitative probability analysis of the TCAS II equipment, Mode S transponder, and altitude information source will be necessary to establish that an incorrect resolution advisory is improbable. For the purposes of a numerical analysis, the probability of an incorrect resolution advisory without a TCAS II failure indication should be on the order of 1.0 x 10-5 per flight hour in the enroute environment and 1.0 × 10-4 per flight hour in the terminal area. The frequency of encounters which would produce a resolution advisory can be assumed to be once per 200 hours in the enroute environment and once per 10 nours in the terminal area, unless the applicant can establish different frequencies based on operational data. These analyses should be provided for the first installation of a particular model of TCAS II equipment. Subsequent installations of the same equipment in other aircraft may make use of the same analyses with particular attention to the differences in own altitude sensors.
f. Test and Evaluation Initial Approval). Testing of the first of a manufacturer's TCAS II system for its initial approval in an aircraft should be conducted to verify that the design and installation performs its intended function under the expected operating conditions, that there are no adverse interactions between the TCAS II and existing aircraft systems, and that prior approvals of present aircraft equipment have not been compromised. The applicant should provide a test plan that includes adequate testing to perform this verification. This test plan will generally require a combination of ground tests, basic flight tests, and flight tests involving planned encounters with another TCAS Il equipped aircratt. The use of other than a transport category aircraft for either the TCAS II installation or for the air-to-air cooperative flights is acceptable. The test plan should contain, as a minimum, the following elements:
(1) Basic Ground Tests.
(i) Bearing Accuracy Tests. Bearing estimation accuracy of the TCAS II system shall be demonstrated as installed in the aircraft.
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bearing accuracy may be measured using a calibrated antenna range that allows precise echo-controlled, far-field, angle-of-arrival measurements at or slightly above zero degrees elevation and over 360 degrees in azimuth. The bearing accuracy may also be measured using a fixed transponder location while rotating the test aircraft on a compass-rose while measuring the bearing angles at 30 degree intervals. Alternately, the airplane is fixed and the transponder may be moved. Manual readout of the bearing estimate may be accomplished directly from a plan position display on the traffic advisory display. Alternatively, the bearing estimates may be automatically recorded or may be read from a special test display. A maximum error of ‡ 15 degrees in azimuth is acceptable; however, larger errors are acceptable in the area of + 45 degrees from the tail and the area is not visible from the cockpit. In this case, aircraft structure may interfere with the signal path.
(ii) Sensor failures. Simulated failures of the aircraft sensors integrated with TCAS II should be evaluated to determine that the resulting system failure state agrees with the predicted results. These tests should be part of the ground test plan.
(iii) Electromagnetic Interference (EMI). A flightdeck EMI survey should be made to determine that the TCAS II equipment is not a source of objectionable conducted or radiated interference to previously installed systems or equipment, and that operation of the TCAS II equipment is not adversely affected by conducted or radiated interference from previously installed systems and equipment. Attention should be given to possible interference with TCAS II equipment from weather radar, particularly if operating in the C-band.
(iv) Evaluate the general arrangement and operation of controls, displays, circuit breakers, annunciators, and placards of the TCAS system.
(v) Self Test. Evaluate the TCAS self test features and failure mode displays and annunciators.
(vi) Verify that the pressure altitude source and radio altimeter are properly interfaced with the TCAS equipment.
(vii) Verify that the windshear and GPWS warnings and TCAS II voice alerts are compatible. Also, verify that windshear warnings can be clearly understood when TCAS II and windshear voice announcements simultaneously occur. If TCAS II, windshear and GPWS aural warnings have been prioritized, the alert priorities should be windshear, GPWS and then TCAS II.
(viii) Verify the performance of TCAS II traffic display by observing any available area traffic.
(ix) Evaluate the TCAS II system installation for satisfactory identification, accessibility, and visibility during both day and night conditions.
(x) Determine that any configuration discretes associated with the TCAS II logic including inhibits of climb RAs, operate properly. (Changes in logic or function with aircraft configuration, altitude, or speed.)
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(xi) Verify that the Mode S identification code and maximum airspeed are correct.
(2) Basic Flight Tests.
(i) During all phases of flight, determine if there is any mutual interference with any other aircraft system. Weather radar should be operating during the flight test.
(ii) 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 mo) with headset covering outboard ear only (when appropriate) and without headsets. 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.
(iii) Demonstrate that traffic information remains valid and usable when the aircraft is pitched ‡ 15 degrees and rolled approximately 30 degrees of bank during normal maneuvers by observing area traffic in the traffic advisory display.
(iv) Evaluate the effective surveillance range of the traffic display, including target azimuth reasonableness and track stability. Use of targets of opportunity or a nontransport (low-speed) aircraft as a target for these tests is permissible.
(v) Determine that any configuration discretes associated with the TCAS II logic including inhibits of climb RAS, operate properly unless previously demonstrated during ground tests. (Changes in logic or tunction with aircraft configuration, altitude, or speed.)
(vi) Perform the additional flight tests in Appendix 2 of this AC unless previously accomplished under TSO-C119a.
(vii) Evaluate TCAS for noninterference during coupled Autopilot and Flight Director approaches to the lowest minimums approved for the aircraft.
(viii) Prior to any cooperative flight tests at any altitude involving the TCAS II equipped aircraft and another aircraft, both aircraft should be flown in close formation to assure matched altimetry readouts.
These checks should be flown at the speeds and altitudes to be used for the tests.
(ix) Evaluate all selectable modes of the TCAS II to determine that they perform their intended function.
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(x) Reevaluate any previously installed aircraft systems that have required changes as a result of the TCAS II installation. (e.g., EFIS, FD, PFD, ND, IVSI, interface, etc.)
(3) Planned Encounter Flight Tests. The objective of these flight tests is to demonstrate adequate ICAS il surveillance and to verity smooth, predictable TCAS II performance. Having established 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 insure that the TCAS II aircraft system performs its intended function by generating TAs and RAs and is consistent with RTCA document DO-185. The intruder aircraft should be equipped with transponders system to a reasonable number of carefully controlled encounters which are likely in service. This matrix covers the envelope of encounter speeds, altitudes, and geometries which have in the past identified flaws in survelllance, logic, and antenna mechanization that were not detected earlier by bench tests.
(i) Intruder overtaking TCAS II aircraft (from the aft quadrants).
(ii) Head-on.
(A) Low and high closure speeds.
(B) Above climb limit, TCAS II to TCAS II.
(C) TCAS II against Mode C with TCAS II above intruder and above climb limit (intent is to force TCAS II aircraft to descend.)
(D) At 3000 feet over calm water to evaluate multipath protection.
(iii) Converging.
(iv) Crossing (intruder above TCAS II, descending or vice versa.)
(v) Evaluate the TA only mode during planned encounters.
(vi) A mix of intruder transponder modes (A, C, and S) should be evaluated, but primary emphasis should be on TCAS Il to TCAS II coordination, and on Mode C replies from the intruder aircraft.
(vii) Evaluate a mix of encounters with TCAS II both above and below the intruder.
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(viii) If a flight test is necessary to insure compatibility with other designs, verify correct air-to-air coordination between the test TCAS II and another manufacturer's previously approved equipment (see paragraph 3c(5)).
(ix) 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.
(4) Mode S Transponder Flight Tests. The flight tests described by this section may be used to obtain the certification of a stand-alone Mode S transponder installation. These tests should also be used to evaluate a Mode S transponder which is intended for use with a TCAS II installation.
purpose of these tests is to primarily verify that the installed antenna (s) are compatible with the Mode S transponder and provide an adequate response to ground radar interrogations during normal aircraft maneuvers. In addition, the flight test is a demonstration 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 is identical or similar to that of previously approved ATCRBS transponder installation.
(i) If the Mode S transponder uses a top mounted antenna in addition to a bottom mounted antenna which is installed at or near the same location used by a previously approved ATCRBS transponder antenna, conduct a comprehensive ground test in accordance with Appendix 3 and conduct 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 ground controller.
(ii) If a Mode S transponder is installed in an aircraft which does not have a previously approved ATCRBS transponder installation or which uses a bottom mounted antenna location which differs significantly from that used by a previously approved ATCRBS transponder antenna, the following ground and flight tests should be conducted.
(A) Conduct Ground Tests Per Appendix 3 (B) Climb and Distance Coverage. Beginning at a distance of at least 1ONM trom, and an altitude of 2000 to 3000 feet above that of the radar facility and using a transponder code assigned by the ATC, fly on a heading that will pass the aircraft over the facility. At a distance of 5 to 1ONM beyond the facility, fly the aircraft at its normal maximum climb attitude to within 90 percent of the maximum altitude for which the aircraft is certificated, maintaining the aircraft at a 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 160NM for turbojet and some turboprop powered airplanes (or 80NM for most other aircraft) from the nearest radar facility. (Distance from the radar facility is a function of the airplane's maximum certificated altitude.) Communicate with the ground radar personnel for evidence of transponder dropout. During 24 Par 3
the flight, check the "ident" mode of the ATC transponder to assure that it is performing its intended function. There should be no dropouts (no return for two or more sweeps). Uncontrollable ringing that hinders use of the ground radar is unsatisfactory.
(C) 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 nearest radar facility. During these turns, the radar displays should be monitored and there should be no signal dropouts (no return for 2 or more sweeps) .
(D) 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 70NM from the nearest 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 2 or more sweeps). Switch the transponder to a code not selected by the ground controller. The aircraft secondary return should disappear from the scope. The controller should then change his control box to "common sense" and a single slash should appear on the scope at the aircraft's position.
(E) 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 nearest radar facility fly on a course which will pass over the radar facility. There should be no transponder dropout or "ring-around".
(F) Surveillance Approach. Beginning at or above 90 percent of the maximum certificated altitude of the aircraft, perform a letdown and approach to a runway of an airport served by Airport Surveillance Radar (ASR) having an ATCRBS facility. The approach should be made at the maximum normal rate of descent and normal approach and landing configuration for the aircraft and 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.
(G) Holding and Orbiting Patterns.
(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.
(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.
(H) 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 Par 3 25
altimeter, when set at or corrected to 29.92 inches of mercury (or equivalent).
g - Follow-On Approvals (STC or Amended TC). Flight testing of TCAS II systems for follow-on approvals (previously approved TCAS Il equipment installed in a different aircraft type) should be conducted to verify that the design and installation performs its intended function under the expected operating conditions, that there are no adverse interactions between the TCAS II and existing aircraft systems, and that prior approvals of present aircraft equipment have not been compromised. The applicant should provide a flight test plan that includes adequate testing to perform this verification.
This test plan will generally require a combination of ground tests, basic †light 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 following elements:
(1) Ground Tests.
(i) Evaluate the general arrangement and operation of controls, displays, circuit breakers, annunciators, and placards of the TCAS II system.
(ii) Evaluate the TCAS II self test features and failure mode displays and annunciators.
(iii) Verify that the pressure altitude source and radio altimeter are properly interfaced with the TCAS II equipment.
(iv) Measure the performance of the directional antenna for 360 degrees coverage at 30 degree intervals, as specified under basic certification ground tests.
(v) Evaluate the TCAS II system installation for satisfactory identification, accessibility, and visibility during both day and night conditions.
(vi) Determine that any configuration discretes associated with the TCAS II logic including inhibits of climb RAs, operate properly. (Changes in logic or function with aircraft configuration, altitude, or speed.)
(vii) Verify that the Mode S identification code and maximum airspeed are correct.
(viii) Verify that the windshear and GPWS warnings and TCAS II voice alerts are compatible. Also, verify that windshear warnings can be clearly understood when TCAS II and windshear voice announcements and GPWS simultaneously occur. If TCAS II windshear and GPWS aural warnings have been prioritized the alert priorities should be windshear, GPWS and then TCAS II.
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(2) Flight Tests.
Proper operation of the traffic display should be verified by observing proximate traffic, at least one traffic advisory and at least one resolution advisory. Confirm that the appropriate aural alerts occur correctly with the traffic advisory and resolution advisory. The advisories may be generated by:
(A) Planned encounters with an intruder aircraft operating a transponder with Mode C capability.
NOTE: Prior to any cooperative flight tests at any altitude involving the TCAS II equipped aircraft and another aircraft, both aircraft should be flown 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.
(C) Encounters with aircraft targets of opportunity.
(D) The use of suitable test equipment, during ground tests.
(ii) During all phases of flight, determine if there is any mutual interference with any other aircraft system.
(iii) Evaluate TCAS Il aural messages for acceptable volume and intelligibility during both low and high cockpit noise levels (idle descent at low speed and high power at mo with and without headsets, covering the outboard ear where appropriate. 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.
(iv) Evaluate the effective surveillance range of the traffic display, including target azimuth reasonableness and track stability.
a nontransport (low-speed) Mode C equipped aircraft as a target or a fixed transponder or suitable test equipment for these tests is permissible.
(V) Evaluate the Mode S transponder air-to-ground ATCRBS function against an appropriate ground facility.
(vi) Determine that any configuration discretes associated with the TCAS II logic including inhibits of climb RAs, operate properly unless previously demonstrated during ground tests. (Changes in logic or function with aircraft configuration, altitude, or speed.)
(vii) Evaluate TCAS II for noninterference during coupled Autopilot and Flight Director approaches to the lowest minimums approved for the aircraft.
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