Wreckage of Air India's Boeing 787-8 aircraft, which was operating flight AI 171 from Ahmedabad to London, placed under tight security, seen a month after the tragedy, in Ahmedabad. The Aircraft Accident Investigation Bureau (AAIB) published its preliminary report on the crash on Saturday.

The crash site of Air India's Boeing 787-8 aircraft, which was operating flight AI 171 from Ahmedabad to London, seen a month after the tragedy, in Ahmedabad.

Police personnel near the crash site of Air India's Boeing 787-8 aircraft, which was operating flight AI 171 from Ahmedabad to London, seen a month after the tragedy, in Ahmedabad.

The crash site of Air India's Boeing 787-8 aircraft, which was operating flight AI 171 from Ahmedabad to London, seen a month after the tragedy, in Ahmedabad.

In this file photo, wreckage of the crashed Air India plane, which crashed into a medical hostel and its canteen complex moments after taking off from the Sardar Vallabhbhai Patel International Airport, being lifted through a crane, in Ahmedabad, Gujarat.

A view of Air India plane crash site in Ahmedabad on the eve of one Month after Air India Plane Crash in Ahmedabad.

In this file photo, charred remains of the Air India plane, that crashed into a medical hostel and its canteen complex moments after taking off from the Sardar Vallabhbhai Patel International Airport, lies on the ground, in Ahmedabad.

In this file photo via PMO, Prime Minister Narendra Modi visits the site of the Air India plane crash, in Ahmedabad. Both switches feeding fuel to the two engines of Air India flight 171 were cut off followed by pilot confusion before the plane crashed in Ahmedabad, seconds after taking off, the first investigation report into the crash has revealed.