Air India Crash: What is a black box? How does it aid the investigation?

Air India Crash: The authorities have found one of the two black boxes, which will help in revealing what triggered the tragic crash of the Air India plane that killed over 240 people on 12 June.

The Black Box in the rear of the aircraft has been found and safely guarded. The Black Box was found on the rooftop of the building on which the Air India plane crashed. A team of the Aircraft Accident Investigation Bureau (AAIB) assisted by 40 personnel from the Gujarat government found the Black Box. The Directorate General of Civil Aviation will collect the equipment to analyse the recordings.

The second Black Box, fixed in the aircraft's front portion, is yet to be found, according to Civil Aviation Munistry officials. 

What is a Black Box?

A Black Box is a small machine that records information about an aircraft during its flight. It is basically a flight recorder, with origins in the early 1950s. This bright orange or yellow rectangular box is crafted to withstand explosions, fire, water pressure, and high-speed crashes.

Invented by Australian scientist David Ronald de Mey Warren, the box is useful in revealing the cause of an aeroplane crash. Warren died in 2010.

The Black Box has two recorders, a cockpit voice recorder for pilot voices and cockpit sounds, and a separate flight data recorder.

How does a Black Box withstand crashes?

The Black Box is made of strong substances such as steel or titanium and is insulated from factors such as extreme heat and cold. It is purposely placed towards the tail end of the aircraft, where the impact of a crash is usually the least.

How does it help in an investigation?

The two black boxes of any aircraft are the cockpit voice recorder (CVR) and the flight data recorder (FDR). These two basically record the information about a flight and help reconstruct the events leading to an aircraft crash.

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

Usually, it takes 10-15 days to analyse the data recovered from the black boxes after a crash.

The black box is an important tool to know what led to the tragic Air India plane crash moments after take-off from Ahmedabad airport on Thursday afternoon. It basically will reveal the underlying reason or responses of the MAYDAY call, or any warnings received by the aircraft.

The Air India B787 Aircraft gave a MAYDAY call to the Air Traffic Control (ATC) immediately after take-off. It, however, did not respond after that to calls made by the ATC to the aircraft, according to a statement from the Directorate General of Civil Aviation (DGCA).

So the last communication from the crew of the ill-fated plane was ‘MAYDAY, MAYDAY…’ followed by radio silence.

What is inside a black box?

A black box comprises four main parts, which are:

-An interface designed to fix the device and facilitate recording and playback

-An underwater locator beacon.

-A 'Crash Survivable Memory Unit' made of stainless steel or titanium, which is designed to withstand a force equivalent to 3,400 times the force of gravity

-The recording chip is on a circuit board.

Investigations in the past?

The investigation of the 2020 Kozhikode plane crash of the Air India Express Flight 1344 was dependent on the aircraft's black box recordings, which revealed that it was due to a pilot error.

The 2015 Germanwings crash was another incident which was investigated using the plane's black box recordings.

History of Black Box

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, according to the International Civil Aviation Organisation (ICAO). The flight was launched for commercial operations in 1952, but saw major accidents in its initial years.

The idea met with initial resistance, including from pilots who argued that the recorders would be used to spy on the crew. By 1956, 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, after two fatal aviation accidents, Australia became the first country to make flight recorders a mandatory legal requirement.

Why is it called a Black Box?

According to the Airbus website, before Warren, French engineer François Hussenot began working on a data recorder in the 1930s. This equipment had 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’.