India's aviation safety watchdog said on Tuesday surveillance conducted on Air India's Boeing 787 fleet did not reveal any major safety concerns, days after one of its jets crashed, killing at least 271 people.

Over the years, numerous improvements in aircraft design, maintenance and operational procedures have resulted from crash investigations. Each incident, especially a fatal one such as the Air India Boeing 787 crash, offers valuable lessons that can drive further enhancements in aviation safety.

An Air India crash Thursday involved a Boeing 787-8 Dreamliner, which the aircraft manufacturer first delivered 14 years ago.

Boeing was generating optimism. Then on Thursday a 787 crashed, raising the specter of fresh problems for Boeing and altering the message it planned to send.

Air India and Boeing are in the midst of significant turnarounds, but knowing the cause of the crash of Flight 171 will take a lengthy investigation.

The Air India flight fell from the sky on Thursday and killed at least 270 people in Gujarat state, officials said Saturday.