The last deadly minutes of AI 171: Timeline of fatal Ahmedabad Air India crash

At 1.44pm on June 12, the air traffic control (ATC) officer at Ahmedabad airport’s control tower heard the word every air traffic controller dreads, and always pray he never has to hear:

‘MAYDAY, MAYDAY, MAYDAY’

What he did not know then was the worst nightmares of many, including their own, was by then already coming true. According to the preliminary report submitted by the Aircraft Accidents Investigation Board (AAIB) to the government this week, ATCO’s immediate reaction was to ask for the plane’s callsign.

That went unanswered.

Here is a timeline of what transpired, as per the AAIB report (timings changed to Indian Standard Time from Universal Time)

1.26pm: Air India AI 171, a Boeing Dreamliner 787-8 aircraft bound for London Gatwick, starts moving out from Bay 34 at Ahmedabad SVP Airport.

11 minutes later: Take-off permission given. The plane starts rolling down the runaway 4 seconds later.

1 minute later: The plane crosses V1 or the take-off decision speed, the point after which the plane is at such a speed that it HAS to take-off.

Six seconds later: The plane takes off.

Three seconds later: The plane achieves its maximum recorded speed. Immediately thereafter, the fuel cut-off switches of BOTH the engines are switched from RUN to CUT-OFF position — with a time gap of just one second. Both engines begin slowing down as fuel supply is cut down, like a car running out of petrol would suddenly stall.

(Same time) The plane starts losing speed even before crossing the perimeter wall of the airport, as both engines fall below minimum idle speed. Immediately, the RAT hydraulic pump, which is an emergency system to power critical systems in the plane in the event of such an engine failure, comes out and starts supplying hydraulic power.

Within roughly the next 1 minute, one pilot asks the other, “Why did you cut-off?

The other one replies, “I did not do so!”

13 seconds after take-off: The fuel switch moves back from CUTOFF to RUN again. The engines' slow down stops, and tries to recover.

18 seconds later: Pilot transmits “MAYDAY MAYDAY MAYDAY”

6 seconds later, at 1.39.11pm: Black boxes stop recording, indicating the plane had crashed.

India