The black box has been found! All aircraft are required to install it. What important information can it provide?

The crash of China Eastern Airlines flight MU5735 on March 21st has touched the hearts of people across the country. There were 123 passengers and 9 crew members on board. At present, all relevant functional departments are still carrying out intensive search and rescue work. What is worrying is that the relevant personnel of the Civil Aviation Administration reported that as of the early morning of the 22nd, the search and rescue work had not found any survivors, but in the afternoon of the 23rd, one of the black boxes on the plane had been found!

Source: Weibo screenshot

In aviation accidents, the process of analyzing the cause of the plane crash and reconstructing the accident is complex and systematic. We often hear in the news that to investigate the cause of the accident, we first need to find the "black box" of the aircraft. So, what is a "black box"?

What is a “black box”?

The official name of the black box is the flight information recording system or flight recorder. It is a device installed on aircraft for accident investigation, maintenance and flight testing. The black box is generally two rectangular blocks about 40 cm long, 20 cm wide and 20 cm high, each weighing about 20 kg to 30 kg. It is usually placed at the tail of the aircraft, where it is usually easier to be preserved intact in the event of an air crash.

Source: News screenshot

The flight information recording system includes two sets of instruments: one is the cockpit voice recorder (CVR), which is actually a tape recorder. The four tracks on the instrument record the conversation between the pilot and the air traffic control, the conversation between the pilot and the co-pilot, the crew's broadcast to the passengers, and various sounds in the cockpit (engine sound, alarm sound). From the beginning of the flight, the black box keeps recording all kinds of sounds in the cockpit, such as conversations, radio transmissions and other sounds. But it can only retain the sound within a certain period of time before stopping recording (maybe 30 minutes to 2 hours).

The second part is the Flight Data Recorder (FDR), which can record various data on the aircraft on magnetic tape in real time, including the aircraft's system working conditions and engine working parameters and other flight parameters. Early recorders could only record more than 20 types of data, but now they can record more than 60 types of data. Among them, 16 types are important data that must be recorded, such as the aircraft's acceleration, attitude, thrust, fuel volume, and the position of the control surfaces.

The black box is not black

The current black box is not actually black, its outer shell is bright orange-red. The name "black box" dates back to 1954, when people first proposed the idea of ​​installing a voice recorder in the cockpit. At that time, all the electronic instruments in the aircraft were placed in black square boxes of uniform size and shape. The voice recorder was placed in the strongest black square box. Although the black box is no longer black, the name "black box" has been retained.

Black Box

Source: Wikipedia

Most of the current black boxes are bright and eye-catching orange-red, which allows search and rescue personnel to quickly find the location of the black box. At present, all black boxes are equipped with a wireless beacon system that can continuously transmit fixed pulse signals, which will provide accident investigators with a basic signal foundation and increase the probability of the black box being found.

After an accident, the black box can continuously transmit radio signals to the outside world for 30 days. In addition to its bright colors, the black box can also withstand explosions, high-temperature combustion, and water immersion. According to relevant regulations, the black box needs to be able to withstand impacts exceeding 3,400 times its own gravity and temperatures exceeding 1,000°C.

With the guarantee of the above technical measures, most of the black boxes, whether they have been hit hard, burned by fire, dropped into the deep sea, or experienced explosions, can be found after the plane crashes, so that the relevant data can be recorded and saved after the air crash, so that people can analyze the cause of the accident and reduce the possibility of the accident happening again.

The invention of the black box

The inventor of the black box is Australian scientist David Warren. The idea of ​​inventing the black box first came from the crash of a Comet jet airliner in 1954.

Comet

Source: Wikipedia

Two years later, Warren and his colleagues tested a black box prototype that could store four hours of voice and flight data, but this black box did not receive support from the Australian aviation community because the Royal Australian Air Force at the time believed that "this type of equipment is not very useful and does not help explain the cause of the accident."

David Warren

Source: Wikipedia

In 1958, a British aviation official saw Warren's invention and agreed to fund him to produce the device in the UK. The black box was then equipped with an earthquake-resistant and fire-proof casing and began to be sold worldwide. Australia, which had previously rejected the black box, became the first country in the world to require all military and civilian aircraft to be equipped with black boxes after an air crash in 1960.

In the following decades, black boxes were promoted in the aviation field around the world and gradually became standard equipment on all civil aviation and most military aircraft in the world. The invention and application of black boxes has made a great step forward in the field of aviation accident analysis.

The accident site of this plane crash is still under search and rescue. We hope that a miracle will happen and that the disaster will not happen again.

This article is compiled from: China News Network, CCTV News, Civil Aviation Administration of China, Wikipedia, public account Global Times, etc.