After a plane crashes, the relevant departments must do everything possible to find the "black box" that has fallen on the plane. Because the black box is the most important and direct evidence for determining the cause of a flight accident. Although called the black box, in fact its color is not black, this is just a common name. Its official name is the flight information recording system. In electronics, instruments that focus only on their input and output signals but do not focus on their internal conditions are collectively referred to as black boxes. The flight information recording system is a typical black box type instrument. For convenience, people in the industry call it a black box and spread it to the public. The public only knows that there is a black box on the plane.
The flight information recording system consists of two sets of instruments: one is a cockpit voice recorder, which is actually a tape recorder. Since the start of the flight, it has continuously recorded all the sounds in the cockpit, such as conversations, announcements and other sounds. However, it can only retain the sound within 30 minutes before the recording is stopped. The second part is the flight data recorder, which records all kinds of data on the aircraft immediately on the tape. Early loggers can only record more than 20 kinds of data, and now the recorded data can reach more than 60 kinds. Of these, 16 are important data that must be recorded, such as the aircraft's acceleration, attitude, thrust, fuel, and the position of the control surface. The recorded time range is the most recent 25 hours. Records 25 hours ago are erased.
With these two recorders, after a certain period of flight, the personnel concerned replayed the records to reproduce the mistakes or malfunctions that have been discovered. Maintenance personnel can use it to easily find the location of the fault; the flight crew can use it to check aircraft flight performance and operational deficiencies, and improve flight technology. Once the plane crashes, this record system becomes the most direct basis for accident analysis. In order to ensure the authenticity and objectivity of the records, the driver can only refer to the contents of the records and cannot control the work of the recorder or change the contents of the records. In order to ensure that the recorder can be preserved even after a plane crash, it must be placed on the safest part of the aircraft. According to statistics, it is known that the tail under the tail of the aircraft is the safest place on the plane, so the "black box" is installed here. The black box is placed in a (or two) heat-resistant, shock-resistant container made of special steel. The container is spherical or rectangular. It can withstand 1000 times its own gravity, withstand high temperatures of 11,000°C for 30 minutes without being damaged. Soak in seawater for 30 days without water. In order to make it easier to find traces of it, ICAO stipulates that the container should be painted in bold orange instead of black or other colors. In its interior is equipped with automatic signal generator can emit radio signals to facilitate air search; also equipped with ultrasonic underwater positioning beacon, when the black box into the water can automatically send ultrasonic signals for 30 days. With these technical measures in place, no matter whether it is a violently blown, fire-ridden, or darkened black box, most of them can be found after a plane crash. According to its records, the aviation accident analysis business has taken a big step forward. The black box is an indispensable part in protecting flight safety, improving aircraft design, and promoting aviation technological progress.