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).
Appendix A Appendix A. Example TCAS II V7.1 AFMS.
INTRODUCTION.
Descriptive material and procedures in this Airplane Flight Manual Supplement (AFMS) example may, when appropriate, be replaced 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), it is then considered an intruder, and an aural and visual traffic advisory (TA) is issued. This level calls attention to what may develop into a collision threat using the traffic advisory 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.
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Appendix A
2. If the intruder gets within 15 to 35 seconds, depending upon altitude, of CPA, it is considered a threat, and an aural and visual resolution advisory (RA) is issued. 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. The TCAS II is considered a backup system to the “SEE AND AVOID” concept and the ATC surveillance. The TCAS II resolution advisories are annunciated 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 be illuminated beginning at zero feet per minute. This can be issued 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 otherwise directed by ATC.
(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. Safe separation will best be achieved 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. Safe separation will best be achieved 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.
(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. Safe separation will best be achieved by not altering the existing vertical speed and climbing or descending through the threat’s flight path.
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.
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Appendix A
(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 additional climb rate is required 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 additional descent rate is required 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 a reversal in direction is required 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 a reversal in direction is required to achieve safe vertical separation from a maneuvering threat aircraft.
A-3
Appendix A Figure A-1. TCAS II/Transponder Control Panel (Example) Table A-1. TCAS II/Transponder Function Selector TEST Holding the TCAS II/Transponder function selector in TEST for 2 to 3 seconds will activate the system test sequence. In the TEST position, read maintenance messages on the display. Use discretion when selecting TEST in flight, since both TCAS II and the transponder will be inhibited for approximately 20 seconds. The function selector is spring loaded to STBY.
STBY Activates TCAS II and XPDR warmup cycles.
XPDR Transponder is on. TCAS II is in warmup cycle.
TA Transponder is on. Only the “Traffic Advisory”, or “TA” function of the TCAS II is on. No “Resolution Advisories” will be received in this position. The written warning “TA ONLY” will appear on the display, and the yellow “RA OFF” flag will be in view on both IVSIs.
TA/RA Transponder is on. All TCAS II functions are on. No TCAS II flags should be present on either IVSI.
XPDR Fail Light (Red) Indicates a transponder system failure when the transponder is on. Comes on during “TEST”, but goes off after approximately 3 seconds if the transponder is OK.
Code Indicator Indicates code selected with the code selectors.
IDENT Causes the word IDENT to flash in the aircraft data block on the ATC display.
ALT RPTG Provides automatic altitude reporting to ATC.
Code Selectors Select the transponder code. Left and right selectors consist of a large knob and a small knob. Each knob controls one digit of the code.
A-4
Appendix A Figure A-2. TCAS II – Traffic Display (Example) Table A-2. Displayed Aircraft Symbols (Examples) Arrow indicates that the target is climbing ↑ or descending ↓ at a rate of at least 500 fpm.
Relative altitude is displayed in the proximity of the aircraft symbol in hundreds of feet. A “+” preceding the relative altitude indicates the target is above you and a “-“ indicates it is below you.
Unfilled white diamond. Non-threatening traffic without altitude reporting. If altitude reporting, the altitude data will be displayed.
+07 Solid White diamond. Proximity traffic 700 feet above. Non-threatening, altitude reporting traffic within 1200 feet vertically and 6nm horizontally. Aircraft without altitude reporting will be assumed to be co-altitude and will be displayed as a solid diamond when within 6nm even though they may not be within 1200 feet vertically.
↓ -03 Solid yellow circle. “TA”, 300 feet below, descending with a rate of at least 500 fpm.
+00 Solid red square. “RA”, level at your altitude.
Own-ship. Airplane symbol in white just below the center of CRT. On a dedicated display or when in the TFC Mode on a combination TCAS II/RADAR Display.
(Compass Arc) This arc is repeater of the Captains compass. (Not required for TCAS II Display) (Range Rings) 3nm – Small ring with ticks at clock positions 5 NM – Large ring made of dots.
A-5
Appendix A Figure A-3. TCAS II Traffic Display (Example) Table A-3A. Paddle Switch REL ALT/FL Switch REL ALT Paddle switch is spring loaded to the center position. Display shows relative altitude “REL ALT” in hundreds of feet above (+) or below (-) your aircraft.
FL Allows display of traffic flight levels, referenced to 29.92, for 15 seconds. Your FL is displayed in lower left corner. Three digits are shown, except for negative flight levels that are shown as – xxx. When the current barometric pressure is not available and the TCAS II aircraft is below FL 180, the FL position is automatically inhibited.
RANGE The maximum forward range on the traffic display is set at range selected by the range knob. Ranges of 3, 5, 10, 20 NM are available and the selected range is annunciated on the traffic display.
BRT Knob Controls brightness of the display.
A-6