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.

The deadly Air India crash last month has renewed a decades-old debate in the aviation industry over installing video cameras monitoring airline pilot actions to complement the cockpit voice and flight data recorders already used by accident investigators.