高考英语最新热点课件：飞机黑匣子是什么？为何叫黑匣子？.pptxVIP

外刊精读课件;Airplane fatalities (死亡) are statistically rare. When they do happen, however, they are often fatal (致命的) and people want answers as to why their loved ones lost their lives, and that is where black boxes come into play.;What is a black box? A black box is an electronic recording device placed in an aircraft for to facilitate (使便利) the investigation of aviation (飞行) accidents and incidents. Black boxes are actually known as flight recorders.;There are two different flight recorder devices: the flight data recorder (FDR) preserves the recent history of the flight through the recording of dozens of parameters (范围) collected several times per second; the cockpit (驾驶舱) voice recorder (CVR) preserves the recent history of the sounds in the cockpit, including the conversation of the pilots. The two devices may be combined in a single unit. A black box is the size of a shoe box.;What does a black box do? The flight data recorder and cockpit voice recorder are compulsory on every commercial flight or corporate jet, and are usually kept in the tail of an aircraft, where they are more likely to survive a crash.;FDRs record things like airspeed, altitude, vertical acceleration and fuel flow and has about 25 hours of recording storage. Together, the FDR and CVR objectively document the aircraft’s flight history, which may assist in any later investigation.;The CVR records the conversation between the pilots as well as with the air traffic control tower. The sounds of switches and engine are also recorded by the device.;However, a cockpit video recorder can store only two hours of cockpit voice recording. The CVRs store the crew’s interactions with each other and air traffic control, but also background noise that can give vital clues to investigators in case of a crash.;How is a black box traced? Equipped with an underwater locator beacon (ULB), if an aircraft crashes into water, the beacon sends out an ultrasonic pulse (超声波脉冲) that is detectable by sonar (声呐) and audio