ordered to keep their seatbelts fastened at all times during the flight.

The new ruling comes after a passenger, travelling on another airline between the US and Far East, was killed earlier this year when the aircraft hit heavy turbulence in mid flight.

Delta Airlines chief operating officer Maurice Worth said: "For decades Delta has recommended that its passengers keep their seatbelts fastened while seated during the flight.

"This simple procedure greatly reduces the chances of a passenger being injured if the flight encounters undetected turbulence.

"We are now taking that recommendation a step further and will this summer begin requiring our passengers to keep their belts fastened.

"We believe our customers will respond positively to our decision and we are of the opinion that this should be a uniform requirement throughout the airline industry.''