The black boxes, which are actually bright orange in colour, are critical in aircraft accident investigations as they provide data on numerous parameters and aircraft systems, helping the investigators identify the most likely causes of an accident.

Investigators probing the deadly Air India crash on June 12 have confirmed that sabotage has not been ruled out. Some 274 victims were killed when the Boeing 787-8 Dreamliner plunged into a building, shortly after it took off from Ahmedabad Airport in India on its journey to London Gatwick in the United Kingdom.

Investigators have downloaded flight recorder data from an Air India crash this month that killed 260 people, India's civil aviation ministry said on Thursday, a long-awaited step towards understanding the world's worst aviation disaster in a decade.