Appendix B B-2
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.
Appendix B B-3
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.
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 shall not be reported using 25-foot increments.
Appendix B B-4 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.
Appendix C C-1
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-toair 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.
Appendix D D-1 Appendix D. Related Documents.
1. 14 CFR Parts. You can apply current portions of 14 CFR for the design, substantiation, certification and operational approval of TCAS II and Mode S transponders. Sections prescribing requirements for these types of systems are listed below. Order copies of 14 CFR Parts 21, 23, 25, 27, 29, 43, 91, 121, and 135 from the Superintendent of Documents, Government Printing Office, Washington, D.C. 20402-9325, telephone (202) 512-1800, fax
(202) 512-2250. You can also get copies from the Government Printing Office (GPO), electronic CFR Internet website at http://www.gpoaccess.gov/cfr/.
14 CFR § 25.301 Loads.
14 CFR § 25.303 Factor of safety.
14 CFR § 25.305 Strength and deformation.
14 CFR § 25.561 General.
14 CFR § 25.603 Materials.
14 CFR § 25.609 Protection of structure.
14 CFR § 25.629 Aeroelastic stability requirements.
14 CFR § 25.869 Fire protection: systems.
14 CFR § 25.1301 Function and installation.
14 CFR § 25.1303 Flight and navigation instruments.
14 CFR § 25.1307 Miscellaneous equipment.
14 CFR § 25.1309 Equipment, systems, and installations.
14 CFR § 25.1316 System Lightning Protection.
14 CFR § 25.1317 High-intensity Radiated Field (HIRF) Protection.
14 CFR § 25.1321 Arrangement and visibility.
14 CFR § 25.1322 Warning, caution, and advisory lights.
14 CFR § 25.1331 Instruments using a power supply.
14 CFR § 25.1333 Instrument systems.
14 CFR § 25.1335 Flight director systems.
14 CFR § 25.1351 Electrical Systems and Equipment: General.
14 CFR § 25.1353 Electrical equipment and installations.
14 CFR § 25.1355 Distribution system.
14 CFR § 25.1357 Circuit protective devices.
14 CFR § 25.1381 Instrument lights.
Appendix D D-2 14 CFR § 25.1431 Electronic equipment.
14 CFR § 25.1541 Markings and Placards: General.
14 CFR § 25.1581 Airplane Flight Manual: General.
14 CFR § 25.1585 Operating procedures.
Note: References to 14 CFR part 25 are appropriate when installing TCAS II on transport category airplanes. When TCAS II is to be certified for non-transport category airplanes, use the equivalents to the above 14 CFR part 25 sections in other parts of the regulations.
2. FAA ACs. You will find a current list of advisory circulars on the FAA Internet website http://www.faa.gov/regulations_policies/advisory_circulars/.
AC 20-131A, Airworthiness Approval of Traffic Alert and Collision Avoidance Systems (TCAS II) and associated Mode S Transponders.
AC 20-115, Radio Technical Commission on Aeronautics (RTCA) Document DO-178B.
AC 25.1309-1 System Design and Analysis.
AC 25-11A, Electronic Flight Deck Displays.
AC 120-55B, Air Carrier Operational Approval and Use of TCAS II.
3. FAA Technical Standard Orders. You will find a current list of TSOs on the FAA Internet website Regulatory and Guidance Library at http://rgl.faa.gov. You will also find the TSO Index of Articles at the same site.
TSO-C112c, Air Traffic Control Radar Beacon System/Mode Select (ATCRBS/Mode S) Airborne Equipment.
TSO-C119c, Traffic Alert and Collision Avoidance System (TCAS) Airborne Equipment, TCAS II.
4. Industry Publications. Order RTCA documents from RTCA, Inc., 1828 L Street N.W.
Suite 805, Washington D.C. 20036 or order online at www.rtca.org.
RTCA/DO-160F, Environmental Conditions and Test Procedures for Airborne Equipment, dated December 6, 2007.
RTCA/DO-178B, Software Considerations in Airborne Systems and Equipment Certifications, dated December 1, 1992.
Appendix D D-3 RTCA/DO-181C (or later revision), Minimum Operational Performance Standards for Air Traffic Control Radar Beacon System/Mode Select (ATCRBS/Mode S) Airborne Equipment, dated June 12, 2001 .
RTCA/DO-185A, Minimum Operational Performance Standards for Traffic Alert and Collision Avoidance Systems II (TCAS II), dated December 16, 1997.
RTCA/DO-185B, Minimum Operational Performance Standards for Traffic Alert and Collision Avoidance Systems II (TCAS II), dated June 19, 2008.
RTCA/DO-300, Minimum Operational Performance Standards for Traffic Alert and Collision Avoidance System II (TCAS II) Hybrid Surveillance, dated December 13, 2006.
5. SAE International. Order SAE documents from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, telephone (724) 776-4970, fax (724) 776-0790. Also, order copies online at www.sae.org.
ARP 926B, Fault/Failure Analysis Procedure, dated June 11, 1997.
ARP 1834A, Fault/Failure Analysis for Digital Systems and Equipment, dated June 1, 1997.
ARP 4102/7, Electronic Displays, dated July 1, 1988.
ARP 4102/8, Flight Deck Head-Up Displays, dated November 1, 1998.
ARP 4754, Certification Considerations for Highly Integrated or Complex Aircraft Systems, dated November 1, 1996.
ARP 4761, Guidelines and Methods for Conducting the Safety Assessment Process on Civil Airborne Systems and Equipment, dated December 1, 1996.
6. AERONAUTICAL RADIO, INC. (ARINC). Publications are available from ARINC, 2551 Riva Road, Annapolis, Maryland 21401; telephone 1-800-633-6882 or online at www.arinc.com.
ARINC 718, Mark 3 Air Traffic Control Transponder (ATCRBS/MODE S), dated December 1989.
ARINC 735, Mark 2 Traffic Alert And Collision Avoidance System (TCAS), dated January 2003.
Appendix D D-4
7. International Civil Aviation Organization (ICAO). Publications are available from ICAO, Attention: Customer Service unit, 999 University Street, Montreal, Quebec, Canada H3C5H7; telephone +1 514-954-8022, facsimile: 514-954-6769, sitatex YULCAYA, email:
sales@icao.int or on line at http://www.icao.int.
Airborne Collision Avoidance System (ACAS) Manual document 9863, First Edition dated 2006.
8. JAA. JAA documents are available from the Information Handling Services (IHS).
Information on prices, where and how to order is available on both the JAA web site:
www.jaa.nl and the IHS web site: www.avdataworks.com. JAA documents transposed to publications of the European Aviation Safety Agency (EASA) are available on the EASA web site at www.easa.eu.int.
JAA Temporary Guidance Leaflet (TGL) 13 Revision 1.
9. EASA. Publications are available on the EASA web site at www.easa.eu.int.
AMC 20-13 Certification of Mode S Transponder Systems for Enhanced Surveillance.
Appendix E
E-1
Appendix E. Definitions and Acronyms.
1. Definitions.
a. Active surveillance. Using TCAS interrogations and subsequent replies to update or acquire a TCAS track.
b. Advisory. Message given to alert the flight crew of converging aircraft and/or a potential collision.
c. Air traffic control radar beacon system (ATCRBS). Secondary surveillance radar system with ground based interrogators and airborne transponders capable of operation on Modes A and C.
d. Alert. Indication (aural or visual) that informs the flight crew in a timely manner about converging aircraft or potential collision.
e. Automatic dependent surveillance broadcast (ADS-B). A function on an aircraft or vehicle that automatically broadcasts its own aircraft's identity, state vector (horizontal and vertical position and velocity), associated quality and performance parameters (accuracy and integrity) and other information. Broadcast links include the 1090 MHz extended squitter (ES) and the universal asynchronous transceiver (UAT) broadcast on 978MHz.
f. Coast. Condition which occurs when TCAS II does not receive a reply to an interrogation from an intruder for which it has established a track, resulting in the logic continuing the track based on previous track characteristics.
g. Corrective resolution advisory (RA). Advises the pilot to either deviate from current vertical speed, such as CLIMB when the aircraft is level, or to maintain an existing climb or descent rate.
Note: In TCAS II Version 7.0 and V7.1, a “Maintain Rate RA” is classified as a corrective RA solely to provide a green fly-to arc or zone on a vertical speed indicator.
h. Discrete. Separate, complete and distinct signal.
i. Failure. Inability of a system, subsystem, unit, or part to perform within previously specified limits.
j. False advisory. Advisory caused by a false track or TCAS II malfunction.
k. Fruit. Intruder replies corrupted by the receipt of undesired transponder replies elicited by ground interrogators and other TCAS II interrogators.
Appendix E
E-2
l. Hybrid Surveillance. Combined use of active and passive surveillance to update a TCAS track.
m. Incorrect resolution advisory (RA). RA occurring when a threat is present, but, because of a failure of the installed TCAS II, Mode S transponder, or associated sensors, commands a maneuver that reduces separation to the threat.
n. Intruder. Aircraft satisfying the TCAS II traffic advisory detection criteria.
o. Mode A. Type of secondary surveillance radar (SSR) equipment or mode of operation that replies by selected 4096 code (nonaltitude) when interrogated.
p. Mode C. Type of secondary surveillance radar (SSR) equipment or mode of operation that replies with aircraft altitude information when interrogated.
q. Mode S. Type of secondary surveillance radar (SSR) equipment that replies to Mode A and Mode C ground interrogations, a discrete address, and other aircraft information in response to interrogations from the ground or air.
r. Other traffic. Aircraft more than ±1200 feet vertical or 6 nautical miles (NM) from own aircraft that are neither RA nor TA.
s. Passive surveillance. The use of airborne position messages to update a TCAS track.
t. Preventive resolution advisory. Requires a pilot to avoid certain deviations from current vertical rate (for example, a Do Not Climb RA when the aircraft is level).
u. Proximate traffic. Aircraft within 6 NM in range and within ±1,200 feet vertically from own aircraft, but does not meet the TCAS II thresholds of a TA or RA.
v. Resolution advisory (RA). Aural voice and display information provided by TCAS II to a flight crew, advising that a particular maneuver should, or should not, be performed to attain or maintain minimum safe vertical separation from an intruder.
w. Resolution display. Shows vertical guidance depicting areas to “fly to” and/or avoid above or below the TCAS II equipped aircraft.
x. Sense. A direction that an RA may take (either Climb or Descend) relative to the existing flight path of own aircraft.
y. Threat. An intruder that satisfies the threat detection logic and thus requires an RA.
z. Track. Estimated position and velocity of a single aircraft based on correlated surveillance data reports.
Appendix E
E-3
aa. Traffic. Aircraft with an operating transponder capable of being tracked and displayed by a TCAS-equipped aircraft.
bb. Traffic advisory (TA). Aural voice and display information from TCAS II to a flight crew, identifying the location of nearby traffic meeting certain minimum separation criteria.
cc. Traffic display. Horizontal position of transponder-equipped aircraft relative to the TCAS II equipped aircraft.
2. Acronyms.
Table E-1 Acronyms.
Acronym Definition 14 CFR Title 14 of the Code of Federal Regulations ACARS Aircraft communications a ddressing and reporting system ADS-B Automatic dependent surveillance - broadcast AFM Airplane flight manual AFMS Airplane flight manual supplement AGL Above ground level ASR Airport surveillance radar ATA Air Transport Association ATC Amended type certificate ATC Air traffic control ATCRBS Air traffic cont rol radar beacon system CAS Collision avoidance algorithm , or CAS logic CRS CAS requirements specification dB Decibel DRVSM Domestic reduced ver tical separation minimum EADI Electronic attitude display indicator EFIS Electronic flight instrument system EHSI Electronic horizontal situation indicators EMI Electromagnetic interference FAA Federal Aviation Administration FD Flight director FHA Functional hazard assessment FL Flight level
Appendix E
E-4
Table E-2 Acronyms. (continued)
FMEA Failure modes and effects analysis FPM Feet Per Minute GPS Global positioning system GPWS/TAWS Ground proximity warning system /terrain awareness warning system HUD Heads-up device ICAO International Civ il Aviation Organization IVSI Instantaneous vert ical speed indicators MHz Megahertz NAS National Aerospace System ND Navigation display NM Nautical mile PFD Primary flight display RA Resolution advisory SARP Standards and Recommended Practices STC Supplemental type certificate TA Traffic advisory TC Type certificate TCAS II Traffic alert and collision avoidance system TSO Technical standard order TTP TCAS transition program Vmo Maximum operating limit speed