The NTSB head said that Boeing's safety checks suggested that a smoke event would occur less than once every 10 million flight hours.

BBC: Boeing gets permission for Dreamliner test flights

The team checked the responses of seal mothers by recording the number of pup checks made (where the mother raises her head off the ground and moves it in the direction of her young to check their well-being) during a specific time period.

BBC: Seal pup

Diplomats have routinely expressed concern about the safety of Burma's domestic airlines, which have been unable to modernise their fleets because of sanctions, and whose safety checks are not published, the BBC's south-east Asia correspondent Jonathan Head reports.

BBC: Burma Air Bagan emergency landing kills two at Heho