You must have heard reference being made to black box whenever any airplane crashes. Immediate efforts are made to recover this black box. When Jumbo Jet Kanishka of Air India crashed, its black box was searched and recovered from the deep sea, by a robot. Do you know, what is this black box and what information it gives regarding the causes of the plane crash? Most of the airplanes on International flights have been using two important instruments since 1960. These instruments are known as digital flight data recorder and cockpit voice recorder. These instruments are enclosed in two steel boxes separately to provide safety. These two enclosed boxes are called ‘black box’. These steel boxes are made of such insulating material, which can withstand a temperature of 1000°C up to half an hour. They are also not affected by shocks. The tape used in these instruments is made of stainless steel, which is not affected by sea water for two days. Flight data recorder is placed in the rear of the plane while cockpit voice recorder is put in the cockpit of the plane. Flight data recorder is a multi-channel recorder. Its tape is made of stainless steel, which is very elastic. Its length is about 6000 feet and it can record the data of a 25 hours flight. It records the temperature of the plane, its velocity and direction of flight, sound of the engine, readings of various instruments, wind velocity etc. This recorder has the capacity to record 64 parameters. These parameters provide a clue about the accident of the plane. It takes several weeks to decode and analyse the data recorded on the tape. Cockpit Voice Recorder is a tape recorder with magnetic tape. This tape records the conversation among the crew members in the cockpit. It also records the sound of explosion. These voices come to the recorder with the help of a microphone fitted in the cockpit. This recorder keeps a record of the events that have occurred during the last half an hour. Prior information is wiped off automatically. In this way this tape is used repeatedly. When an airplane meets with an accident, efforts are made to recover these instruments in order to learn the causes of the accident. Recorded information is analysed and the reasons of accident are established. In fact, this electronic equipment records details of the flight.