'Major fault' to blame for North Sea air crash

Air accident investigators are focusing on the theory that "catastrophic mechanical failure" caused a helicopter carrying oil-rig workers to crash into the North Sea, killing 11 men.

Air accident investigators are focusing on the theory that "catastrophic mechanical failure" caused a helicopter carrying oil-rig workers to crash into the North Sea, killing 11 men.

A specialist salvage vessel carrying divers and remote-controlled submarines will start work today at the scene of Tuesday night's tragedy to search for the bodies of six victims believed to have remained trapped in the Sikorsky S-76, sitting in 30 metres of water about 45 miles off the Norfolk coast.

The 12-hour overnight rescue mission to find survivors from the helicopter, which was on a routine flight to shuttle workers between rigs operated by the oil giant Shell, was called off at 7am yesterday as the coastguard confirmed that no one had withstood the impact.

A support vessel carrying the bodies of five victims found on the surface within two hours of the crash docked in Great Yarmouth at 5am amid sombre scenes as colleagues stood in an informal guard of honour.

As Air Accident Investigation Branch (AAIB) experts began their enquiry, rescuers revealed that the twin-engined Sikorsky, the workhorse of the offshore drilling industry, had simply fallen from the sky at 7.45pm in fine weather as it made its approach to the Santa Fe Monarch exploration rig towards the end of a 90 minute journey.

Colin White of Great Yarmouth Coastguard, which received the first SOS signal from the Santa Fe Monarch, said: "It seems that it just dropped into the sea. Investigators are at the scene – it seems to have been a catastrophic mechanical failure."

The owners of the S-76, aviation firm Bristow, which is one of Britain's biggest helicopter operators, said the crashed aircraft was 21 years old and was being flown by two of its most experienced pilots.

Air safety experts said that a sudden failure, possibly of a tail rotor blade or gearbox, was the most likely explanation adding that the fact that no distress signal was received meant the crash had happened in seconds. The S-76 is designed to be able to glide to an emergency landing in the event of engine failure and is equipped with inflatable flotation bags to allow passengers and crew time to evacuate when ditching in water.

David Learmount, Safety editor of Flight International magazine, said: "There is only one reason why this aircraft could have come down without everybody surviving and that's because it must have been totally out of control.

"This is one of those accidents that should not have happened. It did not take place at the most dangerous time, take off or landing; it happened when it was cruising and there was no reason for anything to go wrong."

The helicopter, YHBH1, which had taken off from Bristow's base at Norwich airport at around 6.30pm, was on the penultimate leg of a journey which took it around four Shell gas and oil platforms. It was one of several trips already completed that day by the aircraft. It had just picked up eight passengers from the Clipper gas platform.

Clive Mather, chairman of Shell UK, said the firm had suspended all flying operations in the southern North Sea until the cause of the tragedy was pinpointed.

One of the victims was named as Angus MacAthur, 38, of the Isle of Lewis, Ross-shire. He left behind a wife and two young sons. Norfolk police said the names of the remaining dead would not be released until tomorrow. They include six men from Norfolk, two from Teesside and one each from Lancashire and Suffolk.