A REVIEW of offshore helicopter operations in the North Sea is being launched in the wake of the latest fatal crash, with experts set to compare the UK's safety record against Norway.

The Civil Aviation Authority said it was taking the step because "considerable effort" by regulators, operators and the offshore industry to minimise the risks had failed to prevent five helicopter ditchings in the last four years, two of which were fatal.

However, critics have warned that the review - which is set to report its findings early in the new year - will lack detail.

An inquiry by the Air Accidents Investigation Branch (AAIB) into the most recent Super Puma crash off Shetland on August 23 is still ongoing.

An interim report published earlier this month said there was no evidence that the incident, where a Super Puma L2 suddenly dropped out of the sky during a routine flight from the Borgsten Dolphin platform to Shetland, was caused by a mechanical failure. It was carrying 16 people and two crew at the time, and four of the passengers were killed.

The incident came four years after another tragedy involving a Super Puma L2 which crashed in the North Sea off Aberdeenshire in April 2009 after its gearbox suffered a "catastrophic failure". All 16 on board were killed.

The CAA review will be led by its head of flight operations, Captain Bob Jones, in conjunction with independent experts, the Norwegian CAA and the European Aviation Safety Agency.

It will include a comparison study of UK operations against those of Norway amid concerns UK safety is lagging behind.

Statistics show Norwegian and UK offshore helicopters had similar fatality rates between the 1960s and 1990s, but in the last decade the UK's record has worsened while Norway's has improved. The last fatal offshore helicopter accident in Norway was in 1997.

The review will also focus on operators' decision-making and internal management, protection of passengers and crew, pilot training and helicopter airworthiness.

Mark Swan, director of the CAA's Safety and Airspace Regulation Group, said: "The recent accidents have understandably given rise to concerns, particularly with offshore workers who rely so heavily on these flights.

"We are committed to ensuring operations are as safe as possible. The review we are announcing today will thoroughly examine the risks and hazards of operating in the North Sea and how these can be managed most effectively."

However, Unite Scottish ­Secretary Pat Rafferty said workers needed a forensic analysis of offshore health and safety.

He added: "It's getting more difficult to take the industry seriously over its approach to safety reform. Already Super Puma L2 types are starting to return to commercial service in the North Sea and they do so without any changes to capacity, configuration or changes to life-saving contingency plans. This is unacceptable.

"If Oil & Gas UK and key ­stakeholders, including the CAA, are serious about reforming offshore health and safety then they must meaningfully engage with the industry's workers."

Bob Crow, general secretary of RMT, said it was demanding "an investigation into North Sea safety which extends beyond just the use of helicopters but which covers every aspect of the offshore working environment".

Frank Doran, MP for Aberdeen North, said: "A public inquiry is urgent and necessary."

A Department for Transport spokeswoman said: "This review will be conducted in parallel to the Air Accidents Investigation Branch's ongoing investigation into the recent Super Puma incident, which will report independently it has have concluded its investigations."