Opinion Ahmedabad plane crash: Why retrieving black boxes matters in aviation accidents

The London-bound flight crashed soon after taking off from Sardar Vallabhbhai Patel International Airport in Ahmedabad on Thursday afternoon (June 12), with 242 passengers onboard. It could only ascend to less than 600 feet before crashing in the Meghani Nagar area of the city.

The cause of the crash is unclear at this stage. However, as is usual in the aftermath of such incidents, the wreckage will be examined, and black boxes will be retrieved to piece together what happened.

What is a black box?

A black box is simply a flight recorder, with origins in the early 1950s. According to the International Civil Aviation Organisation (ICAO), Australian jet-fuel expert Dr. David Ronald de Mey Warren was recruited to a special team in 1953 to analyse the mid-air explosions being experienced by the world’s first commercial jet aircraft, the de Havilland Comet. It was launched for commercial operations in 1952, but saw major accidents in its initial years.

For example, on May 2, 1953, BOAC Flight 783 departed Kolkata for Delhi, amidst severe rain and thunderstorms, with 43 passengers and crew members. “Six minutes after takeoff, while climbing to 7,500 feet, the plane experienced an in-flight break-up and crashed, killing all on board,” the US Federal Aviation Administration website says.

The UK’s Imperial College’s magazine once reported Warren saying, “I had seen, at a trade fair, a gadget which fascinated me. It was the world’s first miniature recorder to put in your pocket. I put the two ideas together. If a businessman had been using one of these in the plane and we could find it in the wreckage and we played it back, we’d say, ‘We know what caused this’.”

The idea initially drew resistance, including from pilots who worried the recorders would be used to spy on the crew. By 1956, however, Warren created a prototype, named the ARL Flight Memory Unit, which allowed the storage of up to four hours of voice and flight-instrument data.

In 1963, following two fatal aviation disasters, Australia became the first country to make flight recorders a mandatory legal requirement, the magazine noted. In the initial days of the black box, the information was recorded onto a metal strip, which was then upgraded to magnetic drives, succeeded by solid-state memory chips.

Why is it called a ‘black’ box?

The Airbus website notes that even before Warren, French engineer François Hussenot began working on a data recorder in the 1930s. It was equipped with sensors that would optically project around 10 parameters onto a photographic film.

This film ran continuously in a box that was constructed to prevent any light from entering it, lending it the name “black box”. The name has endured, even as the outer box of the recorder has always been orange – a bright colour that makes it easier to identify the metal case.

How do black boxes help understand airplane crashes?

Most aircraft are required to be equipped with two black boxes — the cockpit voice recorder (CVR) and the flight data recorder (FDR) — that record the information about a flight and help reconstruct the events leading to an aircraft accident.

While the CVR records radio transmissions and other sounds in the cockpit, such as conversations between the pilots and engine noises, the flight data recorder records more than 80 different types of information, such as altitude, airspeed, flight heading, vertical acceleration, pitch, roll, autopilot status, etc.

It usually takes at least 10-15 days to analyse the data recovered from the black boxes after a crash.

Where are black boxes placed, and how do they withstand crashes?

The recording devices are stored inside a unit that is generally made out of strong substances such as steel or titanium and are also insulated from factors such as extreme heat, cold or wetness. To protect these black boxes, they are equipped towards the tail end of the aircraft, where the impact of a crash is usually the least.

There have been cases where planes have crashed into water bodies. To make black boxes discoverable in situations where they are underwater, they are equipped with a beacon that sends out ultrasound signals for 30 days. However, in certain cases, like the Malaysian Airlines MH370 flight, the recorders weren’t found.