Nepal Flight Crash: How Does an Aircraft's Black Box Work?

At least 68 people have been confirmed dead in the Yeti Airlines aircraft crash in Nayagaun in Nepal on Sunday, 15 January. While the cause for the crash is yet to be determined, what will be instrumental in narrowing this down is the black box on board the 72-seater ATR aircraft. The black box, an on-board data recorder, is instrumental in identifying the reason behind the aircraft crash, and what could have potentially led to it.What does a black box contain? What information can it provide investigators? How is it designed to survive a crash that can destroy an aircraft? Keep reading.A black box refers to two pieces of equipment together – the Cockpit Voice Recorder (CVR) and the Flight Data Recorder (FDR). Together, they provide investigators the data needed to identify what led to a flight crash. Usually, when an aircraft crash happens, like the Nepal flight crash, there's little information on what led to the crash. This is where the two parts of the black box come into action.Flight Data Recorder: The electronic flight data recorder (FDR), also called the Accident Data Recorder, contains information about altitude, flight speed, fuel, turbulence, wind speed, and over a thousand other types of information that can help narrow down a flight's path and what may have gone wrong in its last moments. Modern FDRs are made of titanium or stainless steel and can withstand extreme temperatures. They also have a beacon that can survive for up to 30 days underwater, while transmitting a location signal.FDRs are also made to survive depths over 6,000 metres underwater, while still relaying signals.Cockpit Voice Recorder: A Cockpit Voice Recorder (CVR) is the second half of the black box. It's a device used to record audio of everything that happens on the flight deck, and helps investigators in the event of an accident or incident. The CVR stores audio from the pilots' headsets, microphones, and even the cockpit, via an area microphone.Together, they form – the black box.Every commercial and/or corporate aircraft is mandated by law to carry at least two black boxes on board.Photos: Nepal Plane With 72 On Board, Including 5 Indians, Crashes in Pokhara In terms of science, the term 'black box' is used to refer to a device or a system whose inputs and outputs you can see (in this case the information and audio), but whose internal workings you can't see.While some sources say the term 'black box' originated from the Britain during World War II, others attribute its origin to Wilhelm Cauer, a German scientist. During World War II, the term was also used to refer to the secretive radar and electronic navigational aids used in British aircraft, which were painted in a non-reflective black.However, in modern aircraft the 'black box', i.e., the electronic flight data recorder isn't black. In fact, it's the furthest thing from black, because black tends to be hard to distinguish and pick out from the debris of a crash. Instead, black boxes are painted a bright colour called International Orange, to make them easily distinguishable from crash debris.Most modern black boxes house both units - the FDR and the CVR, inside one box. These black boxes are built of super-strong material like titanium or stainless steel, wrapped with fire and heat-resistant insulation to protect from extreme temperatures. Black boxes can withstand temperatures exceeding 1,100°C for up to one hour, and temperatures of 260°C for 11 hours.Black boxes are equipped with an Underwater Locator Beacon (ULB) which sends out a ping every second for 30 days, if the aircraft crashes into water.ULBs have a battery life of over six years, and can be traced by sonar and audio equipment up to depths of 14,000 feet, and in some cases, 20,000 feet. However, if the crash occurs on land, the ULB does not trigger, indicating that investigators need to scour the area near the crash site for the black box.Before being put into use, black boxes are subjected to extreme stress tests including impact tests(of impacts at speeds exceeding 750 km/h), load tests (of carrying static loads upwards of two tonnes), and heat tests.Additionally, black boxes are also stored at the back of the aircraft, statistically the safest place on the aircraft, to minimise the damage from a crash or an incident.However, as sturdy as they are, coming to a conclusion about what caused a crash, from the data a black box provides, can still take weeks and even months.While black boxes have been used since the 1960s, modern black boxes have advanced significantly, tracking several hundred and even a thousand data parameters simultaneously. However, industry experts have said that there has been stagnation in implementing newer black box technologies, even though they exist.They added that the future of black box technology is likely to include a constant live-stream of data to the air control rooms from the aircraft, rather than a physical black box flight data recorder.But, as of now, like their durable and sturdy design indicates, black boxes are here to stay and are the key to piecing together the last moments of an aircraft disaster.Nepal Plane Crash: All 22 Bodies Recovered From Site, Black Box Retrieved

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Nepal Flight Crash: How Does an Aircraft's Black Box Work?

Information from the black box will help investigators identify the cause of the tragic aircraft crash.