标题: Traffic Alert and Collision Avoidance System 空中交通警戒与防撞系统 [打印本页] 作者: 航空 时间: 2011-9-19 13:17:04 标题: Traffic Alert and Collision Avoidance System 空中交通警戒与防撞系统
作者: 航空 时间: 2011-9-19 13:21:01
1 NBAA 2003 2 NBAA 2003 Civil Aviation Flight University of China Traffic Alert and Collision Avoidance System 空中交通警戒与防撞系统 TrraaffffiiccAlleerrtt aanndd CoolllliissiioonnAvvooiiddaannccee SSyysstteem((TCASS)) 3 NBAA 2003 Civil Aviation Flight University of China The TCAS, short for traffic-alert and collision avoidance system, is an independent system; it can perform its functions completely without the assistance of any ground system. Such independence is necessary in oceanic and other non-radar airspace. TCAS is an advisory system designed to alert the flight crew to potential conflicts with other transponder-equipped airplanes flying in the same area. If these other airplanes which are usually called intruders, are equipped with an air traffic control radar beacon system ATCRBS or mode S transponder, they will be interrogated and tracked by TCAS. Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) 4 NBAA 2003 Civil Aviation Flight University of China Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) Currently, there are three versions of the TCAS system in use or in some stage of development; TCAS I, II, and VI. TCAS II provides TAs as well as RAs，but only involves vertical evasive movement. In addition, the TCAS II system exchanges data with other TCAS II or higher level systems to coordinate resolution advisories. This is to prevent two TCAS equipped aircraft from executing the same evasive maneuver. TCAS I is a similar system to TCAS II but it is intended for smaller airplanes and does not provide vertical corrective information. TCAS IV provides TAs and RAs involving both vertical and horizontal maneuvers. 5 NBAA 2003 Civil Aviation Flight University of China Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) TCAS II is the most common system and provides the necessary vertical manoeuvre advice. In accordance with the Joint Airworthiness Requirements, as of the year 2000, all commercial aeroplanes over 15 000 kg, and with a seating capacity of 30 or more passengers, when operating in European airspace, must carry TCAS II. 6 NBAA 2003 Civil Aviation Flight University of China The TCAS system consists of an ATC/TCAS control panel, a TCAS computer and directional antennae. The system requires that an operating mode S transponder be installed in the TCAS airplane. The TCAS system interfaces with other navigation systems and uses EFIS displays for visual advisories and the digital audio control system for aural advisories. Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) TCAS II system Display ATC/TCAS Control Panel Mode S XPDR TCAS Computer Directional Antenna Omni-directional Antenna Omni-directional Antenna Other Navigation Systems Omni-directional Antenna Figure 7.1 7 NBAA 2003 8 NBAA 2003 Civil Aviation Flight University of China TCAS Computer The TCAS computer contains a receiver, a transmitter and processors required to determine if nearby airplanes (intruders) will intersect the flight path of the TCAS equipped airplane (own airplane). The TCAS computer interrogates airplanes in the airspace around its own airplane on a frequency of 1,030 MHz, and the computer receives responses to its interrogations on a frequency of 1,090 MHz. The computer uses these responses to track intruders and display the intruder’s bearing and range, and to require vertical avoidance maneuver of the flight crew. Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) Display ATC/TCAS Control Panel Mode S XPDR TCAS Computer Directional Antenna Omni-directional Antenna Omni-directional Antenna Other Navigation Systems Omni-directional Antenna Figure 7.1 9 NBAA 2003 Civil Aviation Flight University of China Antenna TCAS-II installations require top and bottom antennae. The top antenna must be directional and have direction finding capability. The bottom antenna may be either omni-directional or directional. The associated Mode-S transponders installations also require top and bottom antennae. The Mode-S transponder has two complete receivers, one per antenna. Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) Display ATC/TCAS Control Panel Mode S XPDR TCAS Computer Directional Antenna Omni-directional Antenna Omni-directional Antenna Other Navigation Systems Omni-directional Antenna Figure 7.1 10 NBAA 2003 Civil Aviation Flight University of China ATC Transponder The ATC transponder receives pulse-coded signals from air traffic control ground stations and TCAS equipped airplanes. These signals are interrogations. The transponder responds to the interrogations with pulse-coded signals. Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) Display ATC/TCAS Control Panel Mode S XPDR TCAS Computer Directional Antenna Omni-directional Antenna Omni-directional Antenna Other Navigation Systems Omni-directional Antenna Figure 7.1 11 NBAA 2003 Civil Aviation Flight University of China ATC/TCAS Control Panel The ATC/TCAS control panel controls both the ATC and TCAS systems. The control panel is directly connected to the ATC transponder. The mode S transponder sends control information to the TCAS computer. Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) Display ATC/TCAS Control Panel Mode S XPDR TCAS Computer Directional Antenna Omni-directional Antenna Omni-directional Antenna Other Navigation Systems Omni-directional Antenna Figure 7.1 12 NBAA 2003 Civil Aviation Flight University of China Display All information from the TCAS computer concerning responding aircraft transponders is displayed on an electronic vertical speed indicator (VSI) or on the EFIS display. TCAS audio TCAS audio is sent to the digital audio control system to be heard in the flight compartment. Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) Display ATC/TCAS Control Panel Mode S XPDR TCAS Computer Directional Antenna Omni-directional Antenna Omni-directional Antenna Other Navigation Systems Omni-directional Antenna Figure 7.1 13 NBAA 2003 14 NBAA 2003 15 NBAA 2003 Civil Aviation Flight University of China Basic Principles of TCAS The TCAS computer forms a protected area around own airplane. This protected area represents the time until the intruder will be at closest point of approach to own airplane. This “time to endanger” is called TAU. The protected area is called the TAU area. Traffic advisory TAU (TA TAU) defines an area around the TCAS airplane. If this area is penetrated by intruder and the intruder meets the relative altitude restrictions, the TCAS would issue a traffic advisory alert. Resolution advisory TAU is established for RA warning in a similar manner. Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) TCAS II principle of operation Figure 7.2 TA RA 20～48s 15～35s CPA 20～48s 15～35s CPA Resolution Advisory TAU Traffic Advisory TAU 16 NBAA 2003 Civil Aviation Flight University of China Basic Principles of TCAS A TA is normally issued 5 to 20 seconds in advance of the resolution advisory (RA). The RA is issued when time to closest point of approach (CPA) is between 15 and 35 seconds. It is rare, but possible, for a RA to be issued without being preceded by a TA. Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) TCAS II principle of operation Figure 7.2 TA RA 20～48s 15～35s CPA 20～48s 15～35s CPA Resolution Advisory TAU Traffic Advisory TAU 17 NBAA 2003 18 NBAA 2003 19 NBAA 2003 20 NBAA 2003 Civil Aviation Flight University of China Basic Principles of TCAS TCAS performs interrogations of intruder airplane transponders and computes the intruder’s range to own airplane and the rate of change of the range (closure rate). If the intruder is reporting its altitude, the TCAS computer computes the relative altitude and the rate of change of altitude of the intruder. Using replies received by the TCAS directional antenna, the TCAS computer determines the bearing to the intruder. From these data TCAS tracks and continuously evaluates the threat potential of intruders to its own airplane. TCAS provides Traffic Advisories (TA) and Resolution Advisories (RA) to the flight crew. Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) TCAS II principle of operation 21 NBAA 2003 Civil Aviation Flight University of China TCAS Advisories A traffic advisory informs the flight crew of the relative position (distance and usually bearing) of intruders. In addition to relative position, the traffic advisory display shows the intruder’s relative altitude. When appropriate, TCAS provides resolution advisory. The resolution advisory only prescribes maneuvers in the vertical plane. Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) TCAS II principle of operation 22 NBAA 2003 Civil Aviation Flight University of China TCAS Transmission/Reception The TCAS computer exhibits the characteristics similar to an ATCRBS/mode S ground station. It uses interrogation and reply signals from transponders to detect and track intruders. TCAS transmits and receives signals on a top and a bottom directional antenna. Interrogation of transponders is performed on 1,030 MHz and reception of return signals is accomplished on 1,090 MHz. Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) TCAS II principle of operation 23 NBAA 2003 Civil Aviation Flight University of China TCAS Detection TCAS only detects the presence of intruders equipped with operating transponders. Resolution advisories are issued only concerning intruders with active altitude reporting. Intruders with active transponders but not reporting their altitude will be tracked and processed for traffic advisories only. Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) TCAS II principle of operation 24 NBAA 2003 Civil Aviation Flight University of China TCAS Detection Mode S transponders announce their presence by transmitting a downlink message containing the airplane’s mode S, 24 bit address approximately once every second. This transmission is called squitter. TCAS determines the mode S address of mode S intruders by listening for the squitter transmissions or by listening for mode S replies to all call interrogations from ground stations. TCAS will add the intruder to its roll call and interrogate and track the intruder using mode S interrogations. TCAS actively searches for ATCRBS mode C transponder equipped intruders using an ATCRBS only all call. Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) TCAS II principle of operation 25 NBAA 2003 Civil Aviation Flight University of China TCAS Detection If the intruder aircraft is equipped with TCAS II, the two TCAS computers are able to coordinate the resolution advisories in each aircraft to achieve optimum separation, with the least disruption to either. This is designed to ensure that both flight crews do not take the same avoiding action and worsen the danger of collision. Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) TCAS II principle of operation 26 NBAA 2003 Civil Aviation Flight University of China Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) All information from the TCAS computer concerning responding aircraft transponders is displayed on an electronic vertical speed indicator (VSI) or on the EFIS display. TCAS Displays 1 2 4 6 4 1 2 .5 0 .5 -03 -05 +12 TA2.0+02 RNG 10 6 Other Traffic Target Proximate Traffic Target TATarget RATarget Green Arc Red Arc No Bearing Own Airplane Symbol 2 NM Range Ring Figure 7.3 TCAS Displays on Electronic VSI 27 NBAA 2003 28 NBAA 2003 Civil Aviation Flight University of China Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) There are four alternative intruder symbols, indicating the threat potential presented and the vertical movement of the intruder. 1 2 4 6 4 1 2 .5 0 .5 -03 -05 +12 TA2.0+02 RNG 10 6 Other Traffic Target Proximate Traffic Target TATarget RATarget Green Arc Red Arc No Bearing Own Airplane Symbol 2 NM Range Ring 29 NBAA 2003 Civil Aviation Flight University of China Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) • An open diamond symbol in white or cyan. Traffic beyond 6 nm range or more than 1200 ft vertical separation. It is called other traffic target. • A solid diamond symbol in white or cyan. Traffic within 6 nm range, but not computed to present a threat. It is called proximate traffic target. • A solid circle in amber. It is called traffic advisory target. • A solid square in red. It is called resolution advisory target. 1 2 4 6 4 1 2 .5 0 .5 -03 -05 +12 TA2.0+02 RNG 10 6 Other Traffic Target Proximate Traffic Target TATarget RATarget Green Arc Red Arc No Bearing Own Airplane Symbol 2 NM Range Ring 30 NBAA 2003 Civil Aviation Flight University of China Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) Provided that the intruder aircraft is responding with SSR mode C or S, the symbol will show the relative altitude numerically in hundreds of feet. If the intruder is above or below the interrogating aircraft, the numeric annotation will be preceded by a plus or minus sign. If the relative altitude of the intruder is changing by more the 500 ft per minute, it is emphasized by an accompanying arrow pointing up or down, as appropriate. 1 2 4 6 4 1 2 .5 0 .5 -03 -05 +12 TA2.0+02 RNG 10 6 Other Traffic Target Proximate Traffic Target TATarget RATarget Green Arc Red Arc No Bearing Own Airplane Symbol 2 NM Range Ring 31 NBAA 2003 Civil Aviation Flight University of China Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) The circular scale has colored arcs superimposed upon it to indicate safe and unsafe climb and descent rate areas when a resolution advisory exists. Unsafe areas are indicated by a narrow red arc; the advised rate of change of altitude by a broad green arc. 1 2 4 6 4 1 2 .5 0 .5 -03 -05 +12 TA2.0+02 RNG 10 6 Other Traffic Target Proximate Traffic Target TATarget RATarget Green Arc Red Arc No Bearing Own Airplane Symbol 2 NM Range Ring TCAS Displays on Electronic VSI 32 NBAA 2003 Civil Aviation Flight University of China Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) There are two types of RAs, Corrective and preventive. Corrective RAs instruct the pilot to climb or descend at a predetermined rate to avoid a conflict. Preventive RAs instruct the pilot not to change altitude or heading to avoid a potential conflict. 1 2 4 6 4 1 2 .5 0 .5 -05 1 2 4 6 4 1 2 .5 0 .5 +05 6 6 1 2 4 6 4 1 2 .5 0 .5 +03 6 1 2 4 6 4 1 2 .5 0 .5 -03 6 Figure 7.4 TCAS Displays on Electronic VSI 33 NBAA 2003 34 NBAA 2003 Civil Aviation Flight University of China Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) 1 2 4 6 4 1 2 .5 0 .5 +06 1 2 4 6 4 1 2 .5 0 .5 -04 6 6 1 2 4 6 4 1 2 .5 0 .5 -03 6 1 2 4 6 4 1 2 .5 0 .5 +05 6 1 2 4 6 4 1 2 .5 0 .5 -04 6 1 2 4 6 4 1 2 .5 0 .5 +05 6 -08 +08 Figure 7.5 35 NBAA 2003 36 NBAA 2003 Civil Aviation Flight University of China Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) TCAS Displays on EFIS In EFIS equipped aircraft the intruder symbols are displayed on the EHSI and the RA avoidance maneuver is shown by the command bars on the EADI. 11:55 180 RNG 10 2810 / GS 262 TAS 300 300 /20 CRL 5 Advisory (red) Resolution 10 10 10 10 Figure 7.6 37 NBAA 2003 Civil Aviation Flight University of China Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) 10 10 10 10 20 20 10 10 10 10 20 20 10 10 10 10 20 20 20 20 10 10 10 10 Figure 7.7 38 NBAA 2003 39 NBAA 2003 Civil Aviation Flight University of China Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) 10 10 10 10 20 20 10 10 10 10 20 20 10 10 10 10 20 20 20 20 10 10 10 10 Figure 7.8 40 NBAA 2003 41 NBAA 2003 Civil Aviation Flight University of China Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) TCAS Aural Messages Traffic Alert Aural Message “TRAFFIC, TRAFFIC” is announced at the time each traffic advisory is issued. This announcement directs the flight crew to monitor TCAS display as an aid to visually acquiring the intruder. The traffic advisory may be a new intruder or a other or proximity intruder which has been upgraded to a traffic advisory. Normally a traffic advisory will precede a resolution advisory by 15 seconds. 42 NBAA 2003 43 NBAA 2003 Civil Aviation Flight University of China Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) TCAS Aural Messages Resolution Advisory Aural Messages • Preventive Resolution Advisory Aural Message When the EADI airplane symbol is not inside the resolution advisory pitch command, the advisory is preventative. This advisory requires no flight crew action other than ensuring that the airplane symbol does not cross the resolution advisory pitch command. The aural command, “MONITOR VERTICAL SPEED, MONITOR VERTICAL SPEED”, tells the flight crew to maintain the current vertical rate. 44 NBAA 2003 45 NBAA 2003 Civil Aviation Flight University of China Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) TCAS Aural Messages • Corrective Resolution Advisory Aural Message (initial action) When the EADI airplane symbol is inside the resolution advisory pitch command, the advisory is corrective. The aural command “CLIMB, CLIMB, CLIMB” (or DESCEND”) requires a maneuver at the rate indicated by the pitch command, nominally 1500 feet per minute. “CLIMB, CROSSING CLIMB—CLIMB, CROSSING CLIMB”(or “DESCEND”) indicates that own airplane flight path will cross the intruder flight path when performing the maneuver. The aural command “REDUCE CLIMB—REDUCE CLIMB” (or “DESCENT”) tells the flight crew to reduce the rate of vertical speed to that shown on the EADI. 46 NBAA 2003 47 NBAA 2003 48 NBAA 2003 Civil Aviation Flight University of China Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) TCAS Aural Messages • Corrective Resolution Advisory Aural Messages (increased action) Increased action, corrective resolution advisory commands are changes from initial action corrective resolution advisory commands. These commands require flight crew action immediately. The aural command “CLIMB, CLIMB NOW—CLIMB, CLIMB NOW” (or “DESCEND”) follows a descend (climb) advisory and it has been determined by the TCAS computer that a reversal of vertical speed is necessary to provide adequate airplane separation. The aural “INCREASE CLIMB—INCREASE CLIMB” (or “DESCENT”) tells the flight crew to increase the vertical maneuver to the pitch command indicated on the EADI, nominally 2500 feet per minute. 49 NBAA 2003 50 NBAA 2003 51 NBAA 2003 Civil Aviation Flight University of China Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) TCAS Aural Messages End of Threat Aural Message The announcement “CLEAR OF CONFLICT” indicates that the TCAS encounter has ended and the intruder range has started to increase. At this time the flight crew should return to the previous clearance. Self-Test Aural Messages At the end of a TCAS self-test, the TCAS computer announces “TCAS SYSTEM TEST OK” if the TCAS system has passed the BITE test, “TCAS SYSTEM FAIL” if the TCAS computer has failed, or “TCAS SYSTEM TEST FAIL” if an input to the TCAS computer has failed. 52 NBAA 2003 53 NBAA 2003 54 NBAA 2003 协调反向 后方 200节的接近率 后方 400节的接近率Dallllllasss起飞干扰 功能测试 模式 无方位无高度报告 迎面 400节的接近率 迎面 600节的接近率 迎面 1000节的接近率 55 NBAA 2003 Civil Aviation Flight University of China Figure 7.9 Control Panel Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) Control for the TCAS II system is normally provided on a combined ATC/TCAS controller. 2034 ALT SOURCE IDENT 1 2 TCAS TEST 1 2 XPDR STBY XPDR TA TA /RA XPDR FAIL ON A T C T C A S 56 NBAA 2003 57 NBAA 2003 Civil Aviation Flight University of China Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) 2034 ALT SOURCE IDENT 1 2 TCAS TEST 1 2 XPDR STBY XPDR TA TA /RA XPDR FAIL ON A T C T C A S The four-position mode selector switch allows selection of STBY, XPDR, TA ONLY, and TA/RA. The TEST button starts a self-test of the control panel, the ATC, and the TCAS system. The status of the control panel (PASS or FAIL) will be shown in the display window. STBY inhibits the transponder from replying. 58 NBAA 2003 Civil Aviation Flight University of China Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) 2034 ALT SOURCE IDENT 1 2 TCAS TEST 1 2 XPDR STBY XPDR TA TA /RA XPDR FAIL ON A T C T C A S The two-position XPDR select switch selects which transponder shall be active. The two identification code select switches are comprised of inner and outer controls and are used to select the four digit identification code. The four digit octal code ranges from 0000 to 7777 and appeals in the liquid crystal display window along with ATC 1 or ATC 2 (whichever is selected as the active transponder). 59 NBAA 2003 Civil Aviation Flight University of China Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) 2034 ALT SOURCE IDENT 1 2 TCAS TEST 1 2 XPDR STBY XPDR TA TA /RA XPDR FAIL ON A T C T C A S The two position of ALT SOURSE switch allows selection of ADC 1 or ADC 2 as the source for altitude for mode C replies. The amber XPDR fail light comes on for a failed ATC system. Pressing IDENT button turns on a special pulse to be added to the transponder replies for approximately 18 seconds that aids the ground station in identifying the airplane. 60 NBAA 2003 Civil Aviation Flight University of China Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) Crew Response For TCAS II to be effective, the pilot: • must not maneuver on the basis of the Traffic Display or Traffic Advisory; • must not maneuver horizontally; • must obey all TCAS RAs and RA changes including sense reversals; • must initiate the first maneuver required by a RA within 5 seconds of the RA being given; • must initiate any subsequent maneuvers required by RA changes within 2.5 seconds of the RA change; and • conduct all maneuvers so as to generate a vertical acceleration of one quarter of 1 g (0.25 g). 61 NBAA 2003 Civil Aviation Flight University of China Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) Crew Response If the aircraft is under Air Traffic control when a TCAS resolution advisory is received, the pilot is required to obey the TCAS command and inform ATC ‘TCAS climb/descent’ as appropriate. Upon receipt of the TCAS message ‘clear of conflict’, the aircraft must be returned to the ATC assigned flight level. Should a maneuver instruction be received from both TCAS and ATC simultaneously, the pilot is required to obey the TCAS instruction and advise ATC accordingly. 62 NBAA 2003 Civil Aviation Flight University of China Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) Crew Response At radio altitudes of less than 1000 ft the TCAS will not give a resolution advisory involving a descent, and below 1500 ft AGL it will not recommend an increased rate of descent. All resolution advisories are inhibited at radio altitudes of less than 500 ft, and traffic advisories at less than 400 ft. It is usual for GPWS alerts and warnings to take precedence over TCAS, and a windshear warning will be awarded the highest priority. 63 NBAA 2003 64 NBAA 2003 65 NBAA 2003 66 NBAA 2003 67 NBAA 2003 68 NBAA 2003 Civil Aviation Flight University of China Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) The Use of TCAS • TCAS provides no protection against aircraft which either do not have a transponder or the transponder is not switched on. • To maximize the effectiveness of TCAS, all aircraft should be equipped with a transponder and the transponder should be used whenever the aircraft is in flight. • A Mode A/C transponder with pressure altitude encoder is sufficient to provide maximum protection in an encounter with a TCAS I/II equipped aircraft. • TCAS can only display the relative altitude of a threat aircraft and TCAS II can only generate RAs if the threat aircraft is replying Pressure Altitude. 69 NBAA 2003 Civil Aviation Flight University of China Traffic Alert and Collision Avvooiiddaannccee SSyysstteem((TCASS)) The Use of TCAS • Transponder control panels have provision to switch off pressure altitude reporting. This provision is used to allow pilots to disable pressure altitude reporting when the pressure altitude data is known to be erroneous. • To maximize the effectiveness of TCAS, all aircraft should operate at all times with their transponder on and altitude reporting enabled. • Altitude reporting accuracy is verified by ATC. Should this validation fail, the pilot is instructed to disable altitude reporting, the transponder should remain on. The failure should be recorded in the maintenance log. 70 NBAA 2003 TCAS作者: liu5031 时间: 2012-3-10 09:59:01