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Air India's Boeing Dreamliner crash: Inside the cockpit

A court filing revealed that India's air crash investigating body had prepared a cockpit voice recorder transcript, conducted a mental autopsy and moved into the final stages of their investigation into last year's deadly Air India accident. The sequence of events as described by Indian investigators on July 12, last year, is shown below.

Air India Dreamliner VTANB landed at Ahmedabad as AI423 at 05:47 GMT.

07:48 GMT - An aircraft was observed leaving Bay 34 of the airport.

07:55 GMT - Air traffic control granted the taxi clearance to the aircraft. A minute later, the aircraft taxied backwards and positioned itself for takeoff.

08:02 GMT - The aircraft has been transferred from tower to ground control.

08:07 GMT - Take off clearance issued

08:07 GMT - The aircraft started rolling.

Aircraft lifted off at 08:08 GMT. The report stated that "the aircraft air/ground sensor switched to air mode in accordance with liftoff."

08:08 GMT - The aircraft reached its maximum airspeed of 180 knots. "Immediately after, the Engine 1 fuel cutoff switch and Engine 2 fuel shut off switch transitioned one by one from RUN to CUTOFF with a time interval of 1 sec."

The Engine N1 and N2 started to degrade from their takeoff values when the fuel supply was cut off.

In the cockpit recording, one pilot is heard asking another why he cut off.

"The other pilot replied that he didn't do it."

The airport CCTV footage showed Ram Air Turbines (RATs) being deployed immediately after take-off.

The aircraft began to lose height before crossing the perimeter wall of the airport.

The RAT hydraulic pump started supplying power at 08:08 GMT. Both engines "passed the minimum idle speed" and both engines were below it.

The fuel cutoff switch for Engine 1 has been changed from CUTOFF to RUN.

The fuel cutoff switch for Engine 2 has also been changed from CUTOFF (stop) to RUN (run).

When fuel control switches from CUTOFF are changed to "RUN" while the aircraft in flight, each engine's full authority dual-engine control (FADEC), automatically manages a relighting and thrust recovery sequence for ignition and fuel introduction.

Engine 1's core speed deceleration stopped and reversed. It then started to recover. Engine 2 could relight, but it couldn't stop core speed deceleration. It was then re-fuelled repeatedly to increase core acceleration and recovery.

The pilot who sent "MAYDAY Mayday Mayday" at 08:09 GMT.

08:09 GMT - Data recording has stopped.

The Crash Fire tender has left the airport grounds for firefighting and rescue. Reporting by Aditya KALA, Abhijith GANAPAVARAM; Editing by Jamie Freed & Kate Mayberry

(source: Reuters)