Industrial accidents in the UK's offshore oil and gas industry are at record lows, but a series of helicopter losses this year with 33 fatalities has ensured that air safety in the sector is enduring a degree of scrutiny rarely seen before.
The fact that one of the accidents occurred in Canadian offshore operations is of little consolation since it could just as easily have happened in the North Sea and, like the others, involved a state-of-the-art machine.
Even the one non-fatal aircraft loss among them served only to intensify workers' fears when the subsequent rescue operation encountered unexpected difficulties despite the benign conditions.
One major consequence has been the creation by the Oil & Gas UK industry body of a Helicopter Task Group (HTG), while another has been the exposure of strains in its relationship with the British Air Line Pilots' Association (BALPA) which represents most of the aviators in the sector.
The HTG chairman is Bob Keiller, the high-profile chief executive of energy services company Production Services Network which lost one of its own staff in the second of the North Sea accidents.
He says: "Companies involved in the April accident went through a very traumatic time. They have all been involved in press conferences and meetings and it was then we began to realise collectively that this was an area where it was our responsibility as leaders in these companies where we could do more and could do better.
"The confidence in the underlying safety of the helicopter fleet still remains high - but people have been sensitised to any helicopter issues much more than before and they want to know what was the issue and what is being done about it in terms of safety?"
HTG members include exploration and services companies, helicopter operators, trade unions, police and regulators. Relations with BALPA, which is a member, are fractious however, and the union's leadership accuses O&GUK of "interfering" in safety matters where it is "unqualified".
Nevertheless, the group has been highly influential in driving the aviation safety agenda and particularly in selecting issues for prioritisation.
Keiller says: "We have put a high degree of priority on anything that has the potential to reduce the likelihood of an accident ahead of anything that improves the response."
The overwhelming priority was to implement the EASA airworthiness directives on the Eurocopter Super Pumas that are the backbone of the North Sea fleet and which required their brief grounding. In concert with that came action to try to improve the analysis of magnetic chip detector and health and usage monitoring system (HUMS) data pending introduction of newly developed software which was already under trial by the UK Civil Aviation Authority and Bristow Helicopters.
Two infrastructural development programmes nearing completion have also been given renewed impetus - the VHF voice rebroadcasting upgrade to improve controller-pilot communications, and more importantly, the multilateration surveillance system which will provide coverage of most of the North Sea operating area when it enters service next June (see panel).
Keiller says: "We have given a renewal of focus and urgency. We have removed any barriers to its successful completion. There were significant risks that further delays might have occurred had we not had everybody making sure that it didn't happen."
Ironically, however, the issue that has dominated much of the group's time relates to unsuspected problems with the use of locator beacons which were highlighted in the non-fatal Super Puma accident in the North Sea in February. Even though it involved a modern aircraft ditching within sight of a rig in calm conditions, it was nearly two hours before the last survivor was rescued.
An interim Air Accidents Investigation Board (AAIB) report revealed that non-certificated - though legal - wristwatch personal locator beacons (PLB) routinely carried by oil workers caused the higher-powered, more capable electronic locator transmitters (ELT) carried by the pilots and on the dinghies to shut down.
This was due to a "smart" system in the ELTs designed to select a "master" beacon when they are in close proximity and to suppress the signal from the others in order to avoid confusing homing devices and save battery power. The result in the accident was that only the much weaker PLB signal was transmitted and no voice communications were available.
Furthermore, the AAIB discovered that neither the pilots nor passengers realised they should extend the telescopic aerials of the ELTs to provide the maximum range.
Keiller comments: "There are a lot of things that have come out that surprised me that were assumed to be common knowledge."
The result, to the unhappiness of many offshore workers, was that the PLBs were immediately banned from being carried in standby mode in case they accidentally start transmitting, and the HTG has been working energetically to have them reinstated. At the same time the smart capability of the ELTs is being disabled.
BALPA is also unhappy and wants only properly certified PLBs to be allowed, and for the ELT smart functionality to be restored. Paul Cook, BALPA national executive council member and an experienced North Sea pilot says: "You get passengers turning PLBs on in the aircraft and people taking spare ones in their bags. It is very much an electronic placebo but it will not save you and it may kill you.
"On a nice sunny day the aircraft will find the electronic noise and find the casualties with the mark one eyeball but what about on a stormy night?"
More generally BALPA believes that the CAA and Health & Safety Executive are insufficiently rigorous in their regulation of the offshore world and too inclined to bow to industry.Cook says: "We want the regulator to take back his job. The CAA is weak and ineffectual. We cannot allow the tail to wag the dog anymore."
The union's other concern is the use of a ship-mounted recovery device called the Dacon Scoop - a type of net which literally scoops casualties out of the sea but which is promoted as being usable in high sea conditions when other forms of rescue might be unavailable.
Cook says the union has concluded that the device is not safe in the sort of conditions in which it would probably be used and it has a formal policy that pilots should not fly when Dacon is the only or primary envisaged means of rescue, he says. That covers about 5% of North Sea flying and in practice some pilots follow the policy and some do not.
O&GUK says it is "generally in support" of the device but adds: "In the HTG it is something that needs to be discussed, so it is an open issue which we have shelved for a few weeks. We will talk about it and our position might change."
But it may be that the single most important near-term step to be taken is the implementation of the new HUMS analysis software that has been trialled over the past two years at Bristow Helicopters. The system, produced by General Electric Aviation, will take the proportion of faults detectable from the currently estimated 69% to about 86% using artificial intelligence techniques to identify anomalies.
CAA research manager David Howson says: "Currently you look at each gear parameter individually and try to make sense of it but it doesn't always pick up everything.
"Now we put all the data in one pot and do multivar analysis using computers that can cope with as many dimensions as you like.
"Previously you could not make it more sensitive without getting more false alarms and there were a lot of those already. Now you get more sensitivity and get fewer false alarms. Everybody who has seen the results speaks very highly indeed of it."
It is hoped to have about 30% of the UK offshore fleet covered this year and the rest during 2010.
"There are a lot of things
that have come out that
were assumed to be
Chairman, O&G UK Helicopter Task Group