Appendix A 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.
(1) No change from basic airplane flight manual.
SECTION 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.
NOTE: CAUTION! Once a non-crossing RA has been issued, safe operation could be compromised if current vertical speed is changed, 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.
NOTE: WARNING. Noncompliance with a crossing RA by one airplane may result in reduced vertical separation; therefore, safe horizontal separation must also be assured 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, the stall warning stick shaker must be respected 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.
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Appendix A
(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.
The TCAS II RA algorithms are based on the pilot initiating the initial 0.25 g acceleration maneuver within approximately 5 seconds. Pilot response is expected within approximately 2.5 seconds if an additional RA is issued. (The increase rate and rate reversal RAs are based on a
0.35 g acceleration maneuver.) Because of these requirements and the rate limits of the autopilots, all RA responses must be hand-flown and not with the autopilot or autothrottles engaged.
NOTE: Evasive maneuvering should be limited 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.
Modified advisories are posted after the response to an initial advisory has been completed and the TCAS II airplane is projected to have adequate altitude separation from the intruder. The initial RA is said to weaken, indicating a return towards the original flight path or clearance is allowed. When the initial advisory weakens, the green arc is repositioned to indicate level flight, the magnitude of the red arc decreased, and “LEVEL OFF, LEVEL OFF” is announced. The modified RA indicates a return to level flight so that the altitude displacement in response to the initial RA can be minimized. This RA will remain displayed until the “CLEAR OF CONFLICT” aural annunciation is issued. Following the weakening advisory will greatly reduce the ultimate altitude deviation caused by the original corrective resolution advisory.
If a “CLIMB” RA is issued while in the landing configuration, initiate normal go-around procedures.
NOTE: Initiating go-around procedure for a “CLIMB” RA does not mandate a missed approach. It is intended to ensure the airplane is properly configured for the TCAS II maneuver. In most cases, the TCAS II event will be resolved 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 and lack the flight path trends necessary for use in evasive maneuvering. However, unnecessary resolution advisories can be issued by TCAS II when other aircraft are operating at an altitude adjacent to the one that has been assigned to the climbing or descending TCAS aircraft. When climbing or descending A-14
Appendix A 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), a reduction in vertical velocity is recommended until reaching the assigned altitude.
As appropriate, the vertical velocity should be reduced 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.
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 threat aircraft track or altitude information can be lost 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) The TCAS II should be tested using the pilot-initiated self-test feature during cockpit preparation. A successful test is indicated by (provide test results from particular TCAS II system).
(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.
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Appendix A
(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 TA symbol will not be annunciated 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.
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Appendix A TA Mode:
(a) The TA position should only be used 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, RAs will not be issued.
WX-ONLY Mode:
(a) When WX-ONLY mode is selected, traffic information, traffic advisories, and resolution advisories are inhibited on the weather radarscope. Therefore, this mode should be used 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) “CLIMB” RAs are inhibited with flaps greater than XX degrees.
(b) When below 1000 feet AGL, the TCAS II will automatically switch into the TA only mode.
(c) “INCREASE CLIMB” RAs are inhibited with flaps greater than XX degrees.
(d) “DESCEND” RAs are inhibited below 1200 feet AGL while climbing and below 1000 feet AGL while descending.
(e) “INCREASE DESCENT” RAs are inhibited below 1450 feet AGL.
(f) Voice messages are inhibited 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 with aural annunciation inhibited. In this mode, RAs are not issued and current RAs become TAs. The TCAS II remains in TA Only mode for 10 seconds after the windshear or GPWS/TAWS warning is removed. TCAS II aural annunciations are enabled immediately following the removal of the windshear or GPWS/TAWS warning aural annunciation.
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Appendix A
(4) TCAS II Abnormal Procedures:
NOTE: These examples are to show the kinds of abnormal procedures to be developed. Procedures will vary depending upon the installation, such as dual Mode S, and so forth.
RA OFF Flag in IVSI
(a) Verify TCAS II/transponder function selector is in TA/RA position.
(b) If TA/RA is selected 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
(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).
XPDR FAIL Light Illuminated
(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
required. 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.
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Appendix B Appendix B. Transponder Ground Tests & Evaluations.
1. Tests and Evaluations. Using a suitable calibrated transponder test set, conduct the following tests:
NOTE: 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 cause data to be transmitted which produce false targets for the ground ATC surveillance systems or airborne TCAS aircraft. These false indications of “intruder aircraft” could result in unnecessary ATC communications and possibly in TCAS induced aircraft maneuvers. Therefore, conduct such testing in coordination with ATC and use antenna shielding (that is, transmission absorption covers or caps) to prevent test data that could generate false intruder information from being transmitted. Using high-powered, hangar-mounted transponders to conduct ramp testing is NOT an acceptable means for conducting either TCAS or transponder ramp testing.
a. Mode Test. Identifies modes of operation. Interrogations are made in Modes A, C, and S (uplink format 11) to determine which modes the transponder replies to. These are the modes tested during the Auto Test sequence.
b. Reply Delay. Interrogates with valid modes and verifies Reply delay minus Range delay (average of best 8 out of 13 replies) equals:
(1) 128.00 µs (±0.25 µs) for Mode S.
(2) 3.00 µs (±0.50 µs) for ATCRBS.
c. 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:
(1) 0.05 µs for Mode S.
(2) 0.06 µs for Intermode (All-Call).
(3). 0.10 µs for ATCRBS.
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Appendix B
d. ATCRBS Reply. Interrogates with ATCRBS (Modes A and C) interrogations and verifies:
(1) F1 to F2 spacing is 20.3 µs (±0.10 µs).
(2) F1 and F2 pulse width between the 0.5 amplitude point on the leading and trailing edge is 0.45 µs (±0.10 µs).
e. SLS Level. Interrogates with valid ATCRBS Interrogations including P2 pulse.
Interrogations are conducted with P2 level at -9 dB and then again at 0 dB. Test verifies:
(1) Transponder does not reply when P2 level is at 0 dB (UUT is suppressed).
(2) Transponder replies when P2 level is at -9 dB (UUT is not suppressed).
f. ATCRBS-Only All-Call. Interrogates with an ATCRBS-only All-Call and verifies:
(1) If Mode S is valid, no reply is received from a Mode S transponder.
(2) If no Mode S, reply is received from an ATCRBS transponder.
g. Mode S All-Call. Interrogates with the ATCRBS (mode A) Mode S All- Call.
Address received in downlink format (DF) 11 is then used in an uplink format (UF) 4 interrogation to solicit a DF4 reply. The address received is decoded and compared with the address sent.
h. Invalid ICAO 24-bit aircraft address. Interrogates with Mode S interrogations using two addresses different from the address determined by the Mode S All-Call, UF11. Test verifies no reply is received. Addresses used are one greater and 256 greater than the correct address.
i. SPR On/Off. Interrogates with a Mode S interrogation with the Synchronous Phase Reversal (SPR) on, verifying correct reply is received. Then same interrogation is sent again with the SPR off, verifying no reply is received.
j. Mode S UF0. Interrogates with Mode S uplink format 0 (Short air- to-air surveillance, ACAS) verifying reply is received that has correct altitude (compared with Mode C altitude), address (compared with Mode Test address) and format.
k. Mode S UF4. Interrogates with Mode S uplink format 4 (Surveillance, altitude request), verifying reply is received that has correct altitude (compared with Mode C altitude), address (compared with Mode Test address) and format.
l. Mode S UF5. Interrogates with Mode S uplink format 5 (Surveillance, identity request) verifying reply is received that has correct identity (compared with Mode A identity), address (compared with Mode Test address) and format.
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Appendix B
m. Mode S UF11. Interrogates with Mode S uplink format 11, verifying reply is received that has correct address (compared with Mode Test address) and format.
n. Mode S UF16. Interrogates with Mode S uplink format 16 (Long air- to-air surveillance, ACAS), verifying reply, if received, has correct altitude (compared with the Mode C altitude), address (compared with Mode Test address) and format. No reply to UF16 does not fail Mode S in Auto Test.
o. Mode S UF20. Interrogates with Mode S uplink format 20 (Comm A, altitude request) verifying reply received has correct altitude (compared with Mode C altitude), address (compared with Mode Test address) and format. No reply to UF20 does not fail Mode S in Auto Test.
p. Mode S UF21. Interrogates with Mode S uplink format 21 (Comm A, identity request) verifying reply received has correct identity (compared with Mode A identity), address (compared with Mode Test address) and format. No reply to UF21 does not fail Mode S in Auto Test.
q. Acquisition Squitter. Verifies squitters are being received from the UUT every 0.8 to
1.2 seconds.
r. Frequency. Verifies frequency of transponder is 1090 MHz (± frequency tolerance as specified by equipment manufacturer). Frequency is displayed in the Auto Test screen.
s. Diversity. Verifies diversity isolation (power level difference between UUT “On” antenna squitters and “Off” antenna squitters) is greater than or equal to 20 dB. Diversity isolation is displayed in Auto Test screen.
NOTE: To ensure >=20 dB dynamic range, test must be run within 50 feet (15.24 meters) of UUT antenna being tested.
t. MTL Difference. Verifies Receiver Sensitivity (MTL) to Mode A interrogations equals MTL to Mode C interrogations (±1.0 dB).
u. Altitude Reporting. Verifies the reported altitude in the AC field of DF0, DF4, D16, and D20 corresponds to the value provided from the on-board altitude source to the transponder and is reported with the quantization indicated by the Q bit in the AC field. For aircraft with 25 foot or better pressure altitude sources, pressure altitude information should be reported in 25 foot increments. Pressure altitude data obtained from a source with larger than 25-foot resolution must not be reported using 25-foot increments.
NOTE: To ensure the correct reporting of altitude with the proper quantization, the aircraft altitude must be incremented over a 300-foot range in 25 foot increments.
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Appendix C Appendix C. Background.
1. Early TCAS. The airline industry has been working with the Air Transport Association of America (ATA) since 1955 toward a collision avoidance system. It was not until the mid 1970s, however, that research centered on using signals from ATCRBS airborne transponders as the cooperative element of a collision avoidance system. This technical approach allows a collision avoidance capability on the flight deck, which is independent of the ground system. In 1981, the FAA announced our decision to implement an aircraft collision avoidance concept called the Traffic Alert and Collision Avoidance System (TCAS). The concept is based upon agency and industry development efforts in the areas of beacon based collision avoidance systems and air-to-air discrete address communications techniques utilizing Mode S airborne transponder message formats.
a. A short time later, prototypes of TCAS II were installed on two Piedmont Airlines Boeing 727 aircraft, and were flown on regularly scheduled flights. Although the displays were located outside the view of the flight crew and seen only by trained observers, these tests did provide valuable information on the frequency and circumstances of alerts and their potential for interaction with the ATC system. On a follow-on phase II program, a later version of TCAS II was installed on a single Piedmont Airlines Boeing 727, and the system was certified in April 1986, then subsequently approved for operational evaluation in early 1987. Since the equipment was not developed to full standards, the system was only operated in visual meteorological conditions. Although the flight crew operated the system, the evaluation was primarily for the purpose of data collection and its correlation with flight crew and observer observation and response.
b. Later versions of TCAS II manufactured by Bendix/King Air Transport Avionics Division were installed and approved on United Airlines airplanes in early 1988. Similar units manufactured by Honeywell were installed and approved on Northwest Airlines airplanes in late 1988. This limited installation program operated TCAS II units approved for operation as a fulltime system in both visual and instrument meteorological conditions on three different aircraft types. The operational evaluation programs continued through 1988 to validate the operational suitability of the systems.
2. Recent TCAS Developments.
a. Since the early 1990s, an operational evaluation known as the TCAS Transition Program (TTP) collected and analyzed data on the performance and use of TCAS II in both the U.S.
National Airspace System (NAS) and in other airspace worldwide. As a result of these analyses, changes to TCAS II were developed, tested, and implemented in the early to mid 1990s. These changes, collectively known as TCAS II V7.0, were implemented by industry in the late 1990s.
TCAS II V7.0 complies with the International Civil Aviation Organization (ICAO) Standards and Recommended Practices (SARP) for ACAS II. TCAS II V7.0 is mandated for carriage in Australia, India and certain European countries and was mandated for carriage in 2003 by ICAO.
In addition, if you operate an aircraft that is equipped with TCAS II in RVSM airspace, it must be a TCAS II that meets TSO-C119b (V7.0) or a later version.
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Appendix C
b. Investigation of operational problems resulted in changes to TCAS II V7.0. The changes resulting from that investigation resulted in TCAS II V7.1.
c. While developing corrective action for the operational problems, the Federal Aviation Administration (FAA), along with industry representatives, decided to develop performance standards for TCAS II Hybrid Surveillance. That work resulted in creation of RTCA/DO-300, Minimum Operational Performance Standards (MOPS) for Traffic Alert and Collision Avoidance System II (TCAS II) Hybrid Surveillance.
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