航空电子设备-增强型近地警告系统PPT课件.ppt

Civil Aviation Flight University of China,Enhanced Ground Proximity Warning System,增强型近地警告系统,Enhanced Ground Proximity Warning System(EGPWS),Civil Aviation Flight University of China,The GPWS used today has limitations that may contribute to the “Late warning or improper pilot response” and “No warning” categories. Current GPWS alerting functions reply on radio altimeters that cannot sense terrain ahead of the airplane. The result can be very short warning times for flight into quickly rising terrain. Additionally, when on approach at a normal descent rate with gear and flaps in the landing configuration, no terrain warnings are provided, because the GPWS assumes the airplane will land at an airplane. A new generation of GPWS the Enhanced GPWS (EGPWS) is designed to complement the current functions of the GPWS and provide terrain warnings in situations where the current system does not.,Enhanced Ground Proximity Warning System(EGPWS),事故一,1995年12月20日，美利坚航空公司的一架B757飞机（965航班）坠毁于南美哥伦比亚的卡利（Cali）。

飞机撞山前11秒GPWS发出了地形警告，然后坠毁于机场北38海里的12000英尺高的山上，离山顶200英尺处事故二,1996年4月，美国空军的一架CT-43A运输机坠毁于克罗地亚（Croatia）事故处于襟翼和起落架都放下的正常进近中，GPWS已解出了工作Civil Aviation Flight University of China,Enhanced Ground Proximity Warning System(EGPWS),Enhanced GPWS Features,In addition to retaining current GPWS alerting functions, the EGPWS offers two new major features : Look-ahead terrain alerting. Terrain display.,Civil Aviation Flight University of China,Figure 9.1,Enhanced Ground Proximity Warning System(EGPWS), Look-ahead terrain alerting. Terrain display.,Civil Aviation Flight University of China,Enhanced Ground Proximity Warning System(EGPWS),Look-ahead Terrain Alerting,The EGPWS provides caution-andwarning-level alerts to the flight crew about potential terrain conflicts earlier than is possible with the basic GPWS. The alerts are based primarily on the airplane position and barometric altitude information passed to the EGPWS. Either a flight management system (FMS) or global positioning system (GPS) can provide airplane position (latitude and longitude) to the EGPWS.,Figure 9.2,Civil Aviation Flight University of China,Enhanced Ground Proximity Warning System(EGPWS),The barometric altitude referenced to Mean Sea Level (QNH) is provided by the airplane air data system. The EGPWS uses additional air data inputs to determine the airplane flight path and orient the alerting envelopes appropriately. The terrain alerting algorithms continuously computer terrain clearance envelopes ahead of the airplane, which are vertically aligned with the airplane flight path and laterally aligned with the airplane ground track. If these envelopes conflict with data in the terrain database, alerts are activated. The look-ahead caution alert is provided approximately 40 to 60 seconds before a potential terrain conflict, and the look-ahead warning alert is provided approximately 20 to 30 seconds before such a conflict.,Civil Aviation Flight University of China,Figure 9.2,Enhanced Ground Proximity Warning System(EGPWS),Civil Aviation Flight University of China,Enhanced Ground Proximity Warning System(EGPWS),The alerting envelopes are sized by a look-ahead distance in front of the airplane, an altitude offset below the airplane, and a lateral distance on either side of the airplane. The look-ahead distance varies mainly with ground speed. An additional component looks six degrees up to protect against very high terrain. This six-degree component actually looks ahead approximately twice the normal look-ahead distance. The altitude offset is normally 700 feet (213m) below the airplane. The purpose of the offset is to provide terrain alerting when the airplane has less than the normal terrain clearance. The lateral distance is 1/8 nautical mile (0.23km) either side of the airplane ground track and increase gradually out to the look-ahead distance.,Civil Aviation Flight University of China,Enhanced Ground Proximity Warning System(EGPWS),In addition to the look-ahead alerting envelopes, the EGPWS has an additional element of protection, the terrain clearance floor (TCF), which addresses such cases as a barometric altitude error. The TCF is an alerting envelope around each airport based on airplane radio altitude. On a normal three-degree glide path to a runway, the airplane will remain well clear of the TCF alerting envelope. If the airplane penetrates the TCF envelope, it is normally also penetrating the new EGPWS look-ahead alerting envelope, which is based on barometric altitude, so the look-ahead alerts would activate. However, if a barometric altitude error exists, the TCF would provide a radio altitude-based alert.,Civil Aviation Flight University of China,Figure 9.3,Enhanced Ground Proximity Warning System(EGPWS),TCF envelope,TCF envelope,EGPWS的功能,TCF包线,Civil Aviation Flight University of China,Enhanced Ground Proximity Warning System(EGPWS),Terrain Display,The EGPWS terrain display is designed to increase flight crew awareness of the surrounding terrain and to 。