The investigation report says Air India did not carry out those inspections - prompting speculation that the accident could have been caused by faulty switches being flipped by accident. However, in an internal note seen by the BBC, the FAA has since reiterated its belief that the issue did not compromise safety.

An official report on the world’s deadliest aviation accident in a decade, seen by CNN, has answered one key question – but raised others.

The Air India airliner carrying 230 passengers and 12 crew members was on its way to the United Kingdom when it crashed into a building shortly after takeoff on June 12, killing all aboard, except for one survivor, and several people on the ground, according to authorities.