A Cockpit Voice Recorder (CVR) and Flight Data Recorder (FDR) that saves all the performance parameter of flight together constitute the Black box.
Black box is orange in color and situated at the rear end of the airplane, which is the safest area in the aircraft. It is made of stainless steel material that can survive 2000° F for 30 minutes. The CVR can store only the last 30 minutes of conversation. If the crash is unable to stop the recorder in the CVR within 30 minutes, all the important conversation recorded before crash will be destroyed. FDR helps in analyzing engine pressure, location, malfunctioning of any aircraft part and airplane speed.
Black box is considered as the most important tool for aircraft maintenance and for investigation after airplane accident. It proved its importance in an unfortunate airplane accident that took place in the Atlantic Ocean in 2009.
A device known as ULB (Underwater Locator Beacon) sends out ultrasonic waves that help in detecting black box. This device goes down with the airplane if an accident occurs in water. As a result, its detection takes time.
To solve this problem, we need a black box that can float on water. It's used as a data recovery tool as after an accident, the investigating team can take this device and recover the data in it.
Installing a Black box in cars helps insurance companies to recover information such as speed, brake status, the status of the driver seat belt as well as the airbag. All this data helps them to calculate the insurance rate and whether the claim is feasible or not.
Police officers use the information provided by this device for the investigation of car accidents and then try to reconstruct the accident.