Statistics uncovered by the Sunday Herald 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 greatly improved.
The UK offshore sector has now suffered four crashes since 2002, with 38 fatalities. The accident off Shetland on August 23 claimed the lives of Duncan Munro, 46, from Bishop Auckland, County Durham; George Allison, 57, from Winchester, Hampshire; Sarah Darnley, 45, from Elgin, Moray; and 59-year-old Gary McCrossan, from Inverness.
The last fatal offshore helicopter accident in Norway was in 1997, in which 12 people died.
John Taylor, regional industrial organiser with Unite, said a meeting of operators, trades unions and regulators held last week had agreed to hold a review to look at all aspects of the ditching.
"It will compare data from the Norwegian sections and the British sections, it will look at the design of helicopters, the seating and the escape procedure of helicopters," he said.
"There are questions and that is why we are going to compare the data - look at Norway, compare what happens here and try and get to not just the cause of the accident, but any root cause behind that cause."
A detailed analysis by Norwegian-based Sintef, the largest independent research organisation in Scandinavia, shows marked differences in how the UK has performed over the last five decades compared to Norway. Between 1966 to 1989, the fatality rate was 4.1 for the Norwegian sector and 3.7 for the UK sector per million person flight hours.
The UK rate remained lower between 1990-98 - at 1.6 compared to 2.3 for Norway. But between 1999 and 2009, the fatality rate for the UK sector shot up to 5.6 - while Norway, with no fatal accidents, recorded a rate of nil.
The crash off Shetland was the fifth incident involving UK Super Pumas in the North Sea since 2009. Three involved ditchings of the EC225 model, with no fatalities. This led to the grounding of this type of the aircraft, which was given the go-ahead to resume flying earlier this month.
The Super Puma that had been carrying 16 passengers and two crew from the Borgsten Dolphin oil rig to Sumburgh airport in Shetland was a AS332 L2 operated by CHC Scotia, which used to be registered in Norway. The AS332 L2 model was also involved in a crash in the North Sea in April 2009 that killed all 14 passengers and two crew.
The differences in the safety record of the two countries operating in the North Sea were highlighted by the British Airline Pilots Association (Balpa) in a statement issued last week.
The union said its members remained confident in the Super Puma family of aircraft, but called for a review of the five incidents since 2009 involving the aircraft to find out what can be done to improve safety.
The Balpa statement added: "Such an investigation might usefully take a comparative view on the approaches of our Norwegian colleagues, who do things in the same geographic operating area yet with an apparently better safety record."
Andrew Watterson, professor of health effectiveness at Stirling University, pointed to occupational health and safety structure and laws that have been developed in Norway since 2000.
"One Norwegian researcher suggested that improvements in offshore safety in Norway at that time were not due simply to some internal control system but included the introduction of the stringent Norwegian Work Environment Act that gave union representatives the right to stop work when they felt safety was jeopardised," he said.
"This was linked to the maintenance of strong offshore unions with a comprehensive network of trades union-appointed safety representatives."
Watterson added: "The UK trade unions have pressed strongly for improvements and regulatory enforcement in North Sea oil health and safety. With powers similar to those of Norway including rights to stop work, UK workers may be better served than by reliance on vague 'safety cultures' , workforce 'involvement' and far from perfect 'safety cases'."
Henrik Solvorn Fjeldsbo, national officer for health and safety specialising in helicopter safety with Norwegian oil union Industri Energi (IE), said the right to stop work had been used many times.
He said: "That is a basic right that safety delegates have in the working environment act. If something is dangerous or considered dangerous to immediate life or health, they can just lay down the work and no-one - the employers or any other employee - can start work until the problem is fixed. Of course we don't misuse it; it has to be really serious before you take this step."
He described oil companies in Norway as being "very proactive" about safety.
"One thing that has to be taken into
consideration is that there are different sets of rules and regulations in helicopter flying in Norway and the UK sector," Fjeldsbo said. "We believe our way and our regulations are better."
Fjeldsbo also pointed to statistics from the Sintef study that show 11 out of 12 offshore helicopter accidents in the North Sea between 2001-09 involved the UK sector.
"I think it would be naive to say that is a coincidence when the numbers are so big," he added,
The confidence is reflected in the decision by the Norwegian authorities to resume using Super Pumas - which were grounded after the Shetland crash - a day ahead of the UK sector. The Helicopter Safety Steering Group (HSSG) recommended that they should be cleared to fly on Thursday, but the AS332 L2 model will not initially carry passengers.
A statement issued by the Norwegian Cooperation Forum for Helicopter Safety about its decision referred to "key factors" that distinguish Norwegian and UK operations - including different regulations and inspections in Norway.
The investigation into the crash is still ongoing and the UK offshore industry now faces a battle to restore confidence in helicopter operations.
Jake Molloy, regional organiser for the RMT union, said the review to be carried out was part of that process.
"It is part of a parcel of measures to try and rebuild the confidence in the helicopter fleet in the UK," he said.
A spokeswoman for industry body Oil & Gas UK said the HSSG had requested it set up an independent review of UK helicopter operations.
She said it would "certainly involve comparison with other countries".
The spokeswoman added: "Terms of reference will be developed in partnership with all stakeholders, including the trades unions.
"As part of that process, the group conducting that investigation will pursue current and future offshore helicopter safety initiatives and research projects, taking into account research such as the helicopter safety study produced by Sintef Technology and Society Safety Research in Norway."
A spokesman for the Civil Aviation Authority, the UK's aviation regulator, said the fatal accident rate for the UK and Norway was around the same over a long period and "incredibly low". On the issue of the Sintef data, he added: "Very low numbers of incidents mean a very low rate for both countries which is obviously very good for operators and passengers.
"One thing to remember is one incident will change those (figures) significantly - it is always an issue when you deal with such low numbers."