Appendix A A-8 Table A- 4. Above/Norm/Below Switch ABOVE Displays altitude-reporting traffic from 2700 feet below to 9900 feet above the TCAS II aircraft. In this mode, ABOVE shows on the traffic display. This selection has no effect on the functioning of the collision avoidance logic.
NORM Displays altitude reporting traffic from 2700 feet below to 2700 feet above the TCAS II aircraft.
BELOW Displays altitude-reporting traffic from 2700 feet above to 9900 feet below the TCAS II aircraft. In this mode, BELOW shows on the traffic display. This selection has no effect on the functioning of the collision avoidance logic.
OFF-SCALE TRAFFIC ADVISORY - If TCAS II tracks an intruder that is outside the selected range of the display but that has entered the Caution or Warning areas, one-half of the appropriate symbol will appear at the appropriate bearing at the edge of the display area. The symbol will appear in its proper color and its data tag will show, if there is room. For example, a TA intruder with a high closure rate, and which is directly ahead and 300 feet below your airplane will appear as an amber-filled half circle at the 12 o’clock position on the edge of the display area. The data tag “-03” will appear below the half symbol. If this intruder is above your altitude, the data tag is not visible. An off-scale RA intruder will appear as a red-filled half square, with data tag if room permits.
NO BEARING ADVISORIES - When TCAS II cannot track the bearing of an intruder, the traffic advisory will appear in the lower center of the display just below the own-airplane symbol. The advisory will present appropriate color-coded traffic information. This phenomenon usually is a result of either temporary antenna shielding (due to steep bank angles) or a failure in the TCAS II bearing antenna. The display can show up to two lines of information. “TA 5.2 -06↑” for example means an intruder is creating a Traffic Advisory 5.2 nautical miles away, 600 feet below, and climbing in excess of 500 FPM. This advisory is displayed in amber or yellow. “RA 0.6 00” means resolution advisory traffic is 0.6 nautical miles away at the same altitude. This advisory is displayed in red. Lack of bearing information does not degrade TCAS II’s ability to compute a traffic or resolution advisory.
Appendix A A-9
Figure A-4. TCAS II Instantaneous Vertical Speed Indicator (Example)
Table A- 5. Instantaneous Vertical Speed Indicator Indicates vertical speed in feet per minute. The IVSI is a normal instantaneous vertical speed indicator, and the presence of the lights or the flags will not interfere with the ability of the needle to indicate vertical speeds.
RED/GREEN EYEBROW LIGHTS. Eyebrow lights are invisible until they illuminate as part of a TCAS II “RESOLUTION ADVISORY”, or system “TEST”. These lights indicate a vertical speed regime which will provide safe traffic separation. The green lights form a wider band than red lights.
IVSI Status Window Flags T C A S BLACK. Normal operation.
T C A S AMBER FLAG. Indicates Unusable TCAS II information.
Red Arc Green Arc Key to Colors in Figures
Appendix A A-10 T C A S WHITE “RA OFF” FLAG. Always displayed when TCAS II/TRANSPONDER function selector is in STBY, XPDR, or TA. Will also be displayed with selector in RA/TA if RAs are not available.
R A O F F
Appendix A A-11 Figure A-5. TCAS II Examples – Preventive RAs
Appendix A A-12 Figure A-6. TCAS II Examples – Initial Corrective RAs
Appendix A A-13 Figure A-7. TCAS II Examples – Modifications to Initial Corrective RAs
Appendix A A-14 SECTION I – LIMITATIONS.
(1) Pilots are authorized to deviate from their current ATC clearance to comply with a TCAS II resolution advisory (RA).
(2) Maneuvers based solely on a traffic advisory (TA) or on information displayed on the traffic display are not authorized.
SECTION II - EMERGENCY PROCEDURES.
No change from basic airplane flight manual.
SECION III – PROCEDURES.
(1) TCAS II Flight Procedures:
Compliance with a TCAS II resolution advisory (RA) is necessary unless the pilot considers it unsafe to do so, or unless the pilot has information about the cause of the RA and can maintain safe separation for example visual acquisition of, and safe separation from, a nearby aircraft on a parallel approach.
WARNING: Once you get a non-crossing RA, you could compromise safe separation if you change the current vertical speed, except as necessary to comply with the RA. This is because TCAS II-to-TCAS II coordination may be in progress with the intruder airplane, and any change in vertical speed that does not comply with the RA may negate the effectiveness of the other airplane’s compliance with its RA.
WARNING: Noncompliance with a crossing RA by one airplane may result in reduced vertical separation; therefore, you must also ensure safe horizontal separation by visual means.
Because of the limited number of inputs to TCAS II for airplane performance inhibits, in some instances where inhibiting RAs may be appropriate it is not possible to do so. In these cases, TCAS II may command maneuvers that may significantly reduce stall margins or result in stall warning. Therefore, you must respect the stall warning stick shaker when following an RA.
Conditions where this may occur include:
(a) Bank angle in excess of 15 degrees.
(b) One engine inoperative.
(c) Abnormal configurations such as landing gear not retractable, etc.
(d) Leaving airplane in inappropriate configurations when climb RA occurs.
(e) Operation at airports outside of 0 to 5,300 feet MSL or temperatures outside of ISA ±50°F.
(f) Speeds below normal operating speeds.
(g) Buffet margin less than 0.3 g.
Appendix A A-15 The TCAS II RA algorithms assume that the pilot initiates an initial 0.25 g acceleration maneuver within approximately 5 seconds. The pilot must respond within approximately 2.5 seconds if the system issues an additional RA. (You should fly any increase rate and rate reversal RAs using a 0.35 g acceleration maneuver.) Because of these requirements and the rate limits of the autopilots, you must disengage the autopilot and autothrottles and hand-fly all RA responses.
Note: You should limit evasive maneuvering to the minimum required to comply with the RA. Excessive responses to RAs are not desirable or appropriate because of other potential traffic and ATC consequences. From level flight, proper response to an RA typically results in an overall altitude deviation of 300 to 500 feet in order to successfully resolve a traffic conflict.
After the crew has completed its response to an initial advisory and the TCAS II system projects that the airplane will have adequate altitude separation from the intruder, the system will post modified advisories if necessary. The initial RA will “weaken”, indicating that the crew may return towards the original flight path or clearance. When the initial advisory weakens, the green arc repositions to indicate level flight, the magnitude of the red arc decreases, and the system announces “LEVEL OFF, LEVEL OFF”. The modified RA indicates a return to level flight so that the flight crew can minimize altitude deviation in response to the initial RA. This RA will remain displayed until the TCAS II issues a “CLEAR OF CONFLICT” aural annunciation. Following the weakening advisory will greatly reduce the ultimate altitude deviation caused by the original corrective resolution advisory.
If the system issues a “CLIMB” RA while the aircraft is in the landing configuration, initiate normal go-around procedures.
Note: Initiating go-around procedure for a “CLIMB” RA does not mandate a missed approach. The purpose of initiating the go-around procedure in this case is to ensure proper airplane configuration for the TCAS II maneuver. In most cases, the aircraft will be clear of conflict with only minor deviation to the intended flight path, and sufficient time and altitude may exist to recover safely to the desired flight path.
The pilot should not initiate evasive maneuvers using information from the traffic display only or on a traffic advisory (TA) only without visually sighting the traffic. These displays and advisories are intended only for assistance in visually locating the traffic. They lack the flight path trends necessary for use in evasive maneuvering.
TCAS II can issue unnecessary resolution advisories when other aircraft are operating at an altitude adjacent to the one assigned to the climbing or descending TCAS aircraft. When climbing or descending in an environment where these unnecessary advisories are considered likely to occur (based on either airspace design, air traffic communications, visual acquisition or utilization of traffic displays), the flight crew should reduce vertical velocity until reaching the assigned altitude. As appropriate, the flight crew should reduce vertical velocity to a rate between 500 and 1,500 ft/min, when approaching an altitude between 1,000 and 2,000 ft. above or below the altitude assigned in the ATC instruction or clearance.
After deviating from an ATC clearance or instruction in response to a TCAS II RA, notify ATC of the deviation as soon as possible.
Appendix A A-16 Following a TCAS II “CLEAR OF CONFLICT” advisory, the pilot should expeditiously return to the applicable ATC clearance unless otherwise directed by ATC.
Note: The TCAS II may lose the threat aircraft track or altitude information during an RA. If so, the RA will terminate without a “CLEAR OF CONFLICT” annunciation.
(2) TCAS II Operation:
Pilot-Initiated TCAS II self-test:
(a) Test the TCAS II using the pilot-initiated self-test feature during cockpit preparation. (Test pass results from particular TCAS II system) indicates a successful test.
(b) Use of the self-test function in flight will inhibit TCAS II operation for up to (provide time for a particular TCAS II system) seconds.
(c) The ATC transponder will not function during some portion of the self-test sequence.
(d) All aircraft systems providing information to TCAS II must be operating in their normal mode during the Self-Test.
Ground Operation:
(a) (When equipped with a TSO-C119c or earlier TCAS II unit)
(1) To preclude unnecessary transponder interrogations and possible interference with ground surveillance systems, do not activate TCAS (TA or TA/RA mode) until taking the active runway for departure. Selection of XPDR is adequate for ATC and nearby Automatic Dependent Surveillance-Broadcast equipped aircraft to “see” the aircraft while taxiing on the airport surface.
(2) After landing and clearing of the runway, de-select from TA or TA/RA mode. Select XPNDR while taxiing to the ramp area. Upon shutdown, select STBY on the transponder.
(b) (When equipped with a TSO-C119d or later TCAS unit,)
(1) To preclude unnecessary transponder interrogations and possible interference with ground surveillance systems, do not activate TCAS (TA or TA/RA mode) until taking the active runway for departure. Selection of XPDR is adequate for ATC and nearby Automatic Dependent Surveillance-Broadcast equipped aircraft to “see” the aircraft while taxiing on the airport surface.
Note: The TCAS II will not annunciate the TA symbol for any target while own-ship is on the ground when TA or TA/RA mode is selected.
(2) After landing and clearing of the runway, de-select from TA or TA/RA mode. Select XPNDR while taxiing to the ramp area. Upon shutdown, select STBY on the transponder.
TA Mode:
(a) Use TA mode only to preclude unnecessary RAs when intentionally operating near other aircraft such as to closely spaced parallel runways (less than 1200 feet apart).
(b) In TA mode, TCAS II will not issue RAs.
Appendix A A-17 WX-ONLY Mode:
(a) When the crew selects WX-ONLY mode, TCAS II inhibits traffic information, traffic advisories, and resolution advisories on the weather radarscope. Therefore, use this mode only in the event TCAS interferes with weather information. (This example is to show the kind of procedure to be developed. Procedures will vary depending upon installation; such as pop-up display modes, PFD/ND implementation, etc.)
(3) TCAS II System Characteristics:
(a) TCAS II inhibits “CLIMB” RAs with flaps greater than XX degrees.
(b) When below 1000 feet AGL, the TCAS II will automatically switch into the TA only mode.
(c) TCAS II inhibits “INCREASE CLIMB” RAs with flaps greater than YY degrees.
(d) TCAS II inhibits “DESCEND” RAs below 1200 feet AGL while climbing and below 1000 feet AGL while descending.
(e) TCAS II inhibits “INCREASE DESCENT” RAs below 1450 feet AGL.
(f) TCAS II inhibits voice messages below 600 feet AGL while climbing and below 400 feet AGL while descending.
(g) The TCAS II surveillance may not function at distances less than 900 feet.
(h) During windshear and/or GPWS/TAWS warnings, TCAS II switches automatically into a TA only mode and inhibits aural annunciation. In this mode, the system does not issue RAs, and current RAs become TAs. The TCAS II remains in TA Only mode for 10 seconds after removal of the windshear or GPWS/TAWS warning. TCAS II re-enables aural annunciations immediately following the removal of the windshear or GPWS/TAWS warning aural annunciation.
(4) TCAS II Abnormal Procedures:
Note: These examples are to show the kinds of abnormal procedures the applicant should develop. Procedures will vary depending upon the installation, such as dual Mode S and integration with the master caution and warning system.
RA OFF Flag in IVSI (may be accompanied by master caution light and aural annunciations)
(a) Verify TCAS II/transponder function selector is in TA/RA position.
(b) If the crew selects TA/RA and “RA OFF” flag is in view, then the pilot with the operable IVSI (flag not in view) should be the pilot flying.
AMBER FLAG in IVSI (may be accompanied by master caution light and aural annunciations)
(a) Check XPDR FAIL light.
(b) If OFF, select other altitude source.
(c) If ON, select alternate ATCRBS transponder. (TCAS II will no longer be available).
Appendix A A-18 XPDR FAIL Light Illuminated (may be accompanied by master caution light and aural annunciations)
(a) Select alternate ATCRBS transponder. (TCAS II will no longer be available.)
Hybrid Surveillance Failure Annunciation
(a) For installations that are capable of annunciating hybrid surveillance failures to the pilot:
(1) Make a logbook entry to record the failure. No other crew action is necessary. TCAS continues to provide traffic annunciation and collision avoidance protection even when hybrid surveillance has failed.
SECTION IV – PERFORMANCE.
(a) No change from basic airplane flight manual.
Appendix B B-1 APPENDIX B. TRANSPONDER GROUND TESTS & EVALUATIONS.
Tests and Evaluations.
Using a suitable calibrated test set, conduct the following tests:
CAUTION: When conducting any ground 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. Ground maintenance checks or ramp testing (such as altimetry or bearing accuracy testing) can result in data transmissions 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 and use antenna shielding (that is, transmission absorption covers or caps) to prevent transmission of test data that could generate false intruder information. Using high-powered, hangar-mounted transponders to conduct ramp testing is NOT an acceptable means for conducting either TCAS or transponder ramp testing. 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.
B.1 Reply Delay.
Interrogates with valid modes and verifies Reply delay minus Range delay (average of best 8 out of 13 replies) equals:
B.1.1 128.00 µs (±0.25 µs) for Mode S.
B.1.2 3.00 µs (±0.50 µs) for ATCRBS.
B.2 Reply Jitter.
Interrogates with valid modes and verifies, using best 8 out of 13 replies. Reply Jitter (changes In Reply Delay) is less than or equal to:
B.2.1 0.05 µs for Mode S.
B.2.2 0.06 µs for Intermode (All-Call).
B.2.3 0.10 µs for ATCRBS.