Flight data, voice recording: How black box will help unravel Ahmedabad crash

The Air India Ahmedabad-London flight crash in Ahmedabad, one of the deadliest in India's aviation history, has claimed at least 265 lives. In a big breakthrough in the investigation into the crash, the black box of the flight has been recovered from the rooftop of a building the flight hit during the crash.

The black box, an orange-coloured crash-proof device, designed to remain secure at the time of a crash, is crucial in getting to the bottom of an air disaster.

Located near the tail of the plane, the device contains a Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR), both very essential tools in investigating the cause of the accident. While the FDR records all technical data related to the aircraft, the CVR records the cockpit conversation between two pilots until the last minute.

HOW BLACK BOX RECOVERY COULD HELP

The black box is located near the tail of the plane, because usually, an aircraft crashes on the side of the nose. Hence, locating the black box close to the tail could help the investigation team locate it faster.

The FDR in this black box records all the technical data related to the aircraft. Two types of parameters are recorded -- continuous and event-based.

Continuous parameters include engine RPM, throttle position, jet pipe temperature, altitude, airspeed, and switch positions—these are monitored constantly. Event-based parameters, on the other hand, capture sudden or critical events such as oil pressure drops, engine failures, fire warnings, and other emergency signals.

Since the data is not kept in the black box for a long time, it is saved elsewhere, a process called data milking.

The investigation team will match the aircraft's data with its old FDR records and try to see if there were any changes to the parameters in the old data. Even the minutest of changes will be noticed.

COCKPIT VOICE DATA

Before the Air India flight, a Boeing 787-8 Dreamliner, crashed, the pilots gave a mayday call to the Air Traffic Control (ATC). Since the Cockpit Voice Recorder (CVR) in the black box captures the pilots' conversations, especially in the moments leading up to an incident, the audio in this case could reveal what problems the pilots were discussing before the emergency call.

Combined with communication logs from the ATC and signals transmitted by the pilots, this information plays a crucial role in reconstructing events and understanding the cause of the incident.

WHAT MAY HAVE CAUSED CRASH

The exact reason why the Air India flight crashed not even a minute after take-off from the runway is yet to be found out. There could be many reasons, both technical and operational.

A bird strike leading to engine failure, simultaneous failure of both engines (though extremely rare), or a malfunction in the aircraft’s flap system, which plays a critical role in generating lift during takeoff, could be some of the reasons.

According to aviation experts analysing the final footage of the Boeing 787 Dreamliner, it appears the aircraft's flaps may not have been deployed. The video shows the aircraft’s nose pitched upward, suggesting the pilot was attempting to recover control.

The footage also shows the aircraft appearing to sink shortly after becoming airborne, something that is a once-in-a-million likelihood event for one of the world’s most advanced commercial jets, according to experts. However, when multiple failures or anomalies occur simultaneously, the risk of an accident increases significantly.

The Aircraft Accident Investigation Bureau (AAIB) is now examining all possible scenarios. The account of Viswash Kumar Ramesh, the only survivor of the deadly crash, will also be examined. Besides, the probe team will go through all videos of the crash.

The investigation, experts say, could take several weeks or even months.