How the black boxes may help reconstruct events leading to Baramati air crash

Weeks after the Learjet 45 aircraft carrying then Maharashtra Deputy Chief Minister Ajit Pawar and four others crashed on January 28, the Aircraft Accident Investigation Bureau (AAIB) said Tuesday (February 17) that both flight recorders or “black boxes” had sustained fire damage. While data was successfully retrieved from one recorder, the agency has sought foreign technical assistance for the rest. “Both recorders were exposed to intense heat for a prolonged period during the accident and sustained fire damage. The Digital Flight Data Recorder (DFDR), manufactured by L3-Communications, has been successfully downloaded at the AAIB Flight Recorder Laboratory. The Cockpit Voice Recorder (CVR), manufactured by Honeywell, is undergoing detailed technical examination. Assistance has been sought from the Accredited Representative of the State of Manufacture for specialised support in data retrieval,” the AAIB said. The Honeywell flight recorders are primarily manufactured in the US, with the US National Transportation Safety Board (NTSB) serving as the accredited representative for official investigation and regulatory reasons. Initial information from the crash site indicated that low visibility conditions in the area might have played a role in the accident. The data from the recorders, along with the wreckage, are expected to help reconstruct the events leading up to the crash. ## What are black boxes? The black box, or aircraft flight recorder, has been around in some form since the 1930s, when French engineer François Hussenot originated a data recorder equipped with sensors that would optically project around 10 parameters onto a photographic film. The film ran continuously in a box constructed to prevent any light from entering it, lending it the name “black box”. The name has endured ever since, even though the external metal casing has always been orange, to help its speedy identification and retrieval. The invention of the box, however, is credited to Australian jet fuel expert David Ronald de Mey Warren, who was reportedly inspired by a miniature recorder he had seen at a trade fair. While analysing the mid-air explosion of the world’s first commercial jet aircraft, the British de Havilland Comet jetliners in 1953, he concluded that in-flight recordings could help analyse the events leading to the crash. Despite limited success and heavy resistance from pilots who feared increased surveillance, in 1956, he created a prototype he called the ARL Flight Memory Unit, which could store up to four hours of voice and flight instrument data. ## How do black boxes help understand plane crashes? Most aircraft today are mandatorily equipped with two black boxes, the cockpit voice recorder (CVR) and the flight data recorder (FDR). The CVR records radio transmissions and other sounds in the cockpit, including the conversations between the pilots and the engine noises. The FDR, on the other hand, records numerous technical details pertaining to the flight itself, such as altitude, airspeed, vertical acceleration, autopilot status, etc. The FDR data helps investigators to reconstruct the flight by generating a video simulation. This helps them visualise the aircraft’s altitude, power settings, instrument readings and other flight characteristics. It typically takes 10-15 days to analyse the data recovered from the black boxes after a crash. How do black boxes withstand crashes? The recorders are stored inside a unit made of a strong material such as steel or titanium, and are insulated from extreme heat, cold, and wetness. These boxes are equipped towards the tail end of the aircraft, which usually sustains the least impact from a crash. These recorders are equipped with a beacon that can send out ultrasound signals for 30 days, which becomes handy when planes crash into water bodies. However, in some cases, like the Malaysian Airlines MH370 flight, the recorders weren’t found.