Appendix 1
- Bank angle in excess of 15 degrees.
- One engine inoperative.
- Abnormal configurations such as landing gear not retractable,
- Leaving airplane in inappropriate configurations when climb RA occurs.
- Operation at airports outside of 0' to 5,300' MSL or temperatures outside of ISA ‡ 50°F (27.8°C).
- Speeds below normal operating speeds.
- Buffet margin less than 0.3g.
• The TCAS II RA algorithms are based on the pilot initiating the initial .25g incremental maneuver within approximately 5 seconds, and within approximately 2 1/2 seconds if an additional corrective RA increase or reverse is issued. (The reversal is based on a .5g incremental maneuver.)
NOTE Evasive maneuvering must 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.
Preventive advisories are also posted after a corrective advisory has been satisfied and the TCAS II airplane is projected to have adequate altitude separation.
indicating a gradual return to the original flight path or clearance is allowed. As the corrective arc is removed, the magnitude of the red arc decreased preventive RA restricts the rate (vertical speed) the pilot may use in returning to the original flight The RA may soften several times before 'CLEAR OF CONFLICT"; "MONITOR VERTICAL SPEED" will be announced only after the initial downgrading of the corrective RA. Utilizing the softening advisory will greatly reduce the ultimate altitude deviation caused by the original corrective resolution advisory.
o If a "CLIMB" RA is issued while in the landing configuration, initiate normal go-around procedure.
Appendix 1 NOTE Initiating go-around procedure for a "CLIMB" RA does not mandate a missed approach. It is intended to assure the airplane is properly configured for the expected maneuver. In most cases, the IcAs ll event vill 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
• 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, while climbing or descending, modest changes in vertical speed based on traffic display information is not considered evasive maneuvering.
o Following a TCAS II "CLEAR OF CONFLICT" advisory, the pilot should expeditiously return to the applicable ATC clearance unless otherwise directed by ATC.
NOTE There can be a case where the threat aircraft track or altitude information is lost during an RA. In this case, the RA will terminate without a "CLEAR OF CONFLICT" annunciation.
2. ICAS I1 OPERATION:
Pilot-Initiated TCAS II Self-Test:
• 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)
• Use of the self-test function in flight will inhibit TCAS II operation for up to 20 seconds depending upon the number of aircraft being tracked.
o The ATC transponder will not function during some portion of the selftest sequence.
Ground Operation:
• The TCAS II should not be selected out of STBY to TA/RA until just prior to takeoff.
o The TCAS II should be selected to STBY immediately after clearing runway following landing.
Appendix 1
• TA Mode:
• 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 2500 feet apart).
• In TA mode, RAs will not be issued.
WX-ONLY Mode:
o When WX-ONLY mode is selected, traffic information, traffic advisories, and resolution advisories are inhibited on the weather radar scope.
heretore, this mode should be used only in the event ICAS interteres with weather information.
(This example is to show the kind of procedure to be developed.
Procedures will vary depending upon installation; e.g., pop-up display modes, PFD/ND implementation, etc.)
3. ICAS II System Characteristics:
o "CLIMB" RAs are inhibited with flaps greater than XX degrees.
° When below 1000 feet AGL and "CLIMB" RAs are inhibited with flaps greater than XX degrees, the TCAS II will go into the TA only mode.
• "INCREASE CLIMB" RAs are inhibited with flaps greater than XX degrees.
o "DESCEND" RAs are inhibited below 1200 feet AGL while climbing and below 1000 feet AGL while descending.
• "INCREASE DESCENT" RAs are inhibited below 1450 feet AGL.
• All RA and TA voice messages are inhibited below 600 feet AGL while climbing and below 400 feet AGL while descending.
• The TCAS II surveillance may not function at distances less than 900 feet.
o During windshear and/or GPWS warnings, TCAS II switches automatically into a TA only no-voice mode. In this mode, RAs are not issued, current RAs become TAs, and TCAS II aural annunciations are inhibited.
Appendix 1
4. ICAS II Abnormal Procedures:
o RA OFF Flag in IVSI
- Verify TCAS/transponder function selector is in TA/RA position.
- 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 Check XPDR FAIL light.
If OFF select other altitude source.
If ON select alternate ATCRBS transponder. (TCAS II will no longer be available.)
• XPDR FAIL Light Illuminated
- Select alternate ATCRBS transponder. (TCAS II will no longer be available.)
(These examples are to show the kinds of abnormal procedures to be developed. Procedures will vary depending upon the installation; e.g., dual Mode S, etc.)
SECTION 4 - PERFORMANCE
• No change from basic airplane flight manual.
15 (and 16)
Appendix 2 Appendix 2
SUPPLEMENTAL INITIAL CERTIFICATION FLIGHT TESTS Surveillance Flight Tests. The bench tests in Section 2.4 of the TCAS I1 MOPS, DO-185, are designed to verify TCAS II surveillance performance under carefully controlled conditions. A surveillance flight test should be performed to completely validate a TCAS II surveillance design.
A flight test under environmentally stressful conditions should be performed to provide the data for a complete TCAS II Mode C surveillance design validation. The environment includes the combined effects of multipath interference, synchronous garbling and fruit interference as a result of high aircraft density, and ground interrogator interference from multiple ground interrogators.
b. A flight test should be performed for each new TCAS II surveillance design, and whenever major modifications are made to the surveillance function of a previously certified TCAS II. Subject to agreement between the applicant and the certifying office, a major modification is defined as one that is expected to impact on the ability of TCAS II to meet the surveillance performance criteria of paragraph 1.k. below. The tests should be accomplished with all certifiable antenna configurations unless the applicant can demonstrate that a worst-case configuration has been evaluated. Since the surveillance functions to be evaluated by this test are sufficiently independent of installation factors such as aircraft type and specific antenna location, the flight test can be carried out using a smaller non-carrier aircraft. The results of the test are only applicable for initial certification for each manufacturers system.
Flight testing should be accomplished in the Los Angeles basin area, particularly in the vicinity of the Long Beach and Santa Ana airports, since previous tests of TCAS II have shown that this area provides the stressful environment necessary for proper evaluation of TCAS II surveillance. Flight paths should include a representative mixture of the following conditions.
(1) Over-land flights at altitudes between 3000 and 6000 feet,
(2) Over-water flights at altitudes between 3000 and 6000 feet for a duration that is at least 20% of the total required flight duration defined in 1(iv) below, and
(3) Approach and departure flights to Long Beach and Santa Ana airports.
d. The flight test should be conducted on weekends between 10:00 a.m. and 3:00 p.m. when the ground visibility is greater than 5 nmi with a ceiling of at least 10,000 feet to ensure the highest peak traffic densities. Another location may be proposed by the applicant and will be considered as a suitable 1
Appendix 2 alternative to the Los Angeles area if the applicant can demonstrate that the TCAS II surveillance test was conducted in an average density of at least 0.1 transponder-equipped aircraft per sq. nmi and a peak density of at least 0.2 transponder-equipped aircraft per sq. nmi. Density is defined as the number of other transponder-equipped aircraft within 5 nmi of the TCAS II test aircraft divided by the area of a circle of 5 nmi radius. Eight real aircraft target tracks occurring simultaneously within 5 nmi of the TCAS II test aircraft is equivalent to a density of 0.1 transponder-equipped aircraft per sq. nmi. The alternative location should also contain a minimum of three FAA or military secondary surveillance radars located within 30 nmi of the TCAS II aircraft in order to provide an interference environment similar to the Los Angeles area.
Flight testing should be of sufficient duration to record at least 10,000 seconds of target track reports on targets-of-interest. The data should be accumulated during a continuous time period not exceeding 3 hours.
A target-of-interest is defined as any target-of-opportunity that exhibits the following characteristics.
(1) within a 5 nmi range of TCAS in the forward quadrant,
(2) within a 3.5 nmi range of TCAS in the right and left quadrants,
(3) within a 2 nmi range of TCAS in the aft quadrant,
(4) within +/- 5 deg. elevation of TCAS, and
(5) is altitude reporting and airborne.
The number of actual flight hours necessary to collect 10,000 trackseconds of data depends on the aircraft density. For example, a one nour recording in the Los Angeles basin which has a demonstrated minimum average density of 0.1 aircraft per sq.nm would result in approximately 10,000 trackseconds of data on targets-of-interest. It is expected that the applicant will have prior knowledge of the density conditions and will select the flight time necessary to record the appropriate amount of data.
The recorded data should include as a minimum all raw reply reports prior to any duplicate reply elimination, reply merging, reply correlation, processed surveillance track reports that have been declared established, traffic and resolution advisories, internal processor clock, time-of-day. Recorded flight data should be provided to the FAA to permit an independent assessment of surveillance performance in accordance with paragraph 1.h. below. Details concerning the format and data types of the tape data to be provided should be coordinated with the FAA in a timely manner
(1.e., 60 days or more in advance of the availability of the recorded flight data is recommended).
The applicant should perform at least the following specific postflight data analyses:
(1) Identify all recorded surveillance target track reports that are established and that satisfy the criteria for a target-of-interest.
Appendix 2
(2) Identify those established target-of-interest track reports that are associated with real aircraft.
(3) Determine the total number of aircraft-seconds associated with real aircraft and the total number of true track-seconds (i.e., those update intervals in which an established surveillance track report was either coasted or updated with a valid reply) associated with real aircraft.
(4) Determine the TCAS II surveillance track probability as the ratio of the total number of true track-seconds associated with real aircraft to the total number of aircraft-seconds associated with real aircraft.
(5) Identify those established target-of-interest track reports that are not associated with real aircraft.
(6) Determine the total number of track-seconds that are not associated with real aircraft. These are classified as false track-seconds.
(7) Determine the TCAS false track probability as the ratio of the total number of false track-seconds to the total number of aircraft-seconds associated with real aircraft.
i. The data should also be examined to determine whether any single event such as crossing targets, multipath induced image targets, the inability to maintain track at closest-point-of-approach, or a synchronously garbled target dominates the false track rate or the rate at which real targets are dropped.
If the false tracks or dropped tracks are due mostly to one type of interference mechanism or geometric condition, it could indicate a design deficiency in this area even though the overall surveillance track probability and false track ratio is acceptable. If this condition exists, the applicant should present this information and provide an evaluation summary that indicates an acceptable design.
An effective method of evaluating TCAS II data to determine overall surveillance statistics has been developed as a result of the initial design effort associated with TCAS II. This method uses high-resolution plots of range, altitude and bearing reply data verses time to first identify those reply reports that are associated with real aircraft. To accomplish this, the reply reports generated by TCAS II are examined visually in an attempt to recognize patterns in the reply data stream that represent real aircraft. To be effective, this technique requires experience in the analysis of TCAS II surveillance data and enough knowledge of the physical aspects of aircraft flight and of the mechanisms that cause false replies to be able to determine, with reasonable probability, whether a reply is false or real. Each of the identified real aircraft replies are then associated with a real aircraft by 3
Appendix 2 manually and visually tracing through the replies to form real aircraft plots.
The real aircraft plot starts at the first observance of a real reply in the aircraft reply stream and terminates at the last observed real reply in this An overlay of the manually-derived real aircraft plots on a similarly scaled plot of TCAS II processed tracks will identify the TCAS II track reports associated with real aircraft.
The applicant should present to the certification office sufficient data in the form of reply plots, surveillance track plots, printouts, tabulations etc. to substantiate that the Mode C surveillance performance on targets-of-interest, measured as a result of the surveillance flight test, meets or exceeds the following acceptance criteria:
(1) TCAS surveillance probability for targets-of-interest >95%
(2) TCAS false track rate for target-of-interest < 1.2% The applicant should also present an evaluation summary on any single dominant failure event as discussed in 1.h. above.
ICAS to TCAS Coordination Encounters. Planned TCAS II to TCAS II coordination encounters should be performed in order to evaluate the reliability of the overall air to air coordination data link for installed TCAS II and Mode S transponder equipments. The encounters should be flown at 3000 feet over calm water in order to increase the likelihood of multipath and in configurations that maximize the times during which a resolution advisory is present and coordination is taking place. Examples of such encounters are tail chases and side-by-side flights. If the lateral separation necessary for multipath is larger than the separation that maintains the RA, the aircraft can periodically turn in towards each other during side-by-side flights in order to continually initiate RAs. The encounters should be flown so as to involve a reasonable mix of the four quadrants of the TCAS II and transponder antennas. Each TCAS II aircraft should have sufficient recording capability to record the replies received in response to coordination interrogations.
The recorded data should include at least 2000 TCAS coordination scans. The criteria for acceptable performance is as follows:
The probability of a single scan coordination link dropout should be no greater than 0.1%.
b. There should be no coordination link dropouts that exceed one scan in duration.
Appendix 3 APPENDIX 3 TRANSPONDER TESTS Using a suitable calibrated transponder test set, conduct the following tests:
TEST DESCRIPTION
0. 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.
1. Reply Delay Interrogates with valid modes and verifies Reply delay minus Range delay (average of best 8 out of 13 replies) equals:
128.00 us (+0.25 us) for Mode S.
3.00 us (+0.50 us) for ATCRBS.
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:
0.05 us for Mode S
0.06 us for Intermode (A11-Call)
0.10 us for ATCRBS.
3. ATCRBS Reply Interrogates with ATCRBS (Modes A and C) interrogations and verifies:
F, to Fz spacing is 20.3 us (t0.10 us).
F1 and fa pulse width between the 0.5 amplitude point on the leading and trailing edge is 0.45 us (t0.10 us).
4. SLS Level Interrogates with valid ATCRBS Interrogations including P, pulse.
interrogations are conducted with P, level at -9 dB and then again at 0 dB. Test verifies:
Transponder does not reply when Pz level is at 0 dB (UUT is suppressed).
Transponder replies when Pz level is at -9 dB (UUT is not suppressed).
Appendix 3
5. ATCRBS Only All-Call Interrogates with an ATCRBS only All-Call and verifies:
If Mode S is valid, no reply is received from a Mode S transponder.
If no Mode S, reply is received from an ATCRBS transponder.
6. 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 formate (UF) 4 interrogation to solicit a DF4 reply. The address received is decoded and compared with the address sent.
7. Invalid Mode S 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.
8. 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.
9. Mode S UFO 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.
10. 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.
11. 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.
Appendix 3
12. 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.
13. Mode S UF16 Interrogates with Mode S uplink format 16 (Long air to air surveillance, ACAS), veritying 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.
14. Mode S UF20 Interrogates with Mode S uplink format 20 (CommA, altitude request) veritying reply received has correct altitude (compared with Mode C altitude), address (compared with Mode Test address) and format. No reply to UF21 does not fail Mode S in Auto Test.
15. 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.
16. Squitter Verifies squitters are being received from the UUT every 0.8 to 2.4 seconds.
17. Frequency Verifies frequency of transponder is 1090 MHz (‡ MHz). Frequency is displayed in the Auto Test screen.
18. 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 insure ≥ 20 dB dynamic range, test must be run within 50 feet
(15.24 meters) of UUT antenna being tested.
19. MIL Difference Verifies Receiver Sensitivity (MTL) to Mode A interrogations equals MTL to Mode C interrogations (t1.0 dB).
Appendix 3
20. Power Verifies transponder's:
Peak output power (ERP) is greater than 48.5 dBm and less than 57.0 dBm .
Receiver sensitivity (MTL) is -73.0 dBm (14.0 dBm).
*U.S. Government Printing Office: 1993 - 715-000/86028