Lone survivor of Air India crash reveals flickering cabin lights before impact, offering crucial clues in the investigation into the deaths of 52 Brits.

India would not allow a UN investigator to join a probe of a crashed Air India jet that some safety experts had criticized for delays in analysis of crucial black box data, two senior sources familiar with the matter told Reuters.

Investigators have begun analyzing data from the black boxes recovered from the Air India Boeing 787 jet that crashed earlier this month, killing 270 people.