Since 1993, the safety record of helicopter operations on the UK Continental Shelf (UKCS) has been first class, but can this good performance be sustained?

Since the early 1960s, travelers to offshore facilities and vessels on the UKCS have been almost entirely dependent on helicopters to reach their destinations. The scale of this vital activity is clearly illustrated by the more than 44 million passengers who have been transported by helicopter to and from offshore installations and vessels. This level of flying activity has involved more than 6 million flight stages taking about 2.75 million flying hours.
About 400 active helidecks exist on the UKCS, with about half that number on fixed installations. The rest are on floating structures and vessels, presenting a constant challenge to flight crews, particularly when helideck motions near the upper limits of operability.
The helicopters
Five types of helicopters serve the UKCS: the Bell 214ST, AS332 Super Puma and Sikorsky S61N, which are twin-engine heavies, and the AS365 Dauphin and Sikorsky S76, which are medium twins.
As a general rule, heavy twins operate out of Aberdeen, Scotland, and fly sectors (flight stages) with long flight times (in excess of 60 minutes). Medium twins fly mainly out of the regional heliports (Blackpool, North Denes, Norwich and Humberside). They record a high number of sectors and shorter flight times (less than 30 minutes).
Safety performance
During the past 30 years or so, nine fatal helicopter accidents on the UKCS have involved offshore workers. These accidents have accounted for the lives of seven flight crew members, two helicopter landing officers (HLOs) and 71 members of the offshore workforce.
With 45 fatalities, a Chinook accident on the approach to Sumburgh Airport in 1986 is the largest loss of life for a single helicopter in the United Kingdom. The loss in 1981of a Westland Wessex due to a catastrophic component failure caused 13 deaths. A Sikorsky S61 accident at Brent spar in 1990 and Super Puma accident at North Cormorant in 1992 accounted for a further 17 lives lost. Six other fatalities occurred in five separate accidents, including two HLOs killed while supervising operations on helidecks in 1992.
Since 1992 helicopter activity has averaged 203,000 sectors flown with more than 1.5 million passengers carried each year.
Prior to 1993, more than 40 nonfatal reportable accidents occurred. Half were attributed to aircraft component or system failures and defects, 10 to human factors and others due to defective maintenance, weather, excessive vessel motions or helideck turbulence.
Since 1993, nonfatal reportable accidents have dropped to a fairly low level, averaging about one a year. In recent years the causes have been two aircraft component failures (one airframe and one undercarriage), three lightning strikes, a poorly located helideck severely affected by hot turbine exhaust plumes from an adjacent installation and a rollover on a vessel helideck due to excessive motions.
Safety initiatives
UKCS oil and gas industry associations and UK regulators are working to reduce the risks of helicopter operations as much as reasonably practicable. Gaining tangible results for continuous offshore flight safety improvement requires attention to safety initiatives and research programs that enhance performance and efficiency.
The key to making improvements is to jointly develop industry standards and then encourage better communication with full participation from all industry associations and regulators.
The large-scale introduction of health and usage monitoring systems (HUMS). Publication of the Helicopter Airworthiness Review Panel (HARP) report by the Civil Aviation Authority (CAA) in 1984 triggered HUMS development. This led to the formation of the joint CAA/Industry Helicopter Health Monitoring Working Group and in-service trials in the late 1980s. Voluntary introduction of operational HUMS on aircraft started in the early 1990s, and UK operators bore the US $39 million (£25 million) cost of implementation.
HUMS has been highly successful and is mandated by CAA for all UKCS offshore helicopters. It significantly reduced the opportunities for catastrophic component failure by providing information on operating limitations and early detection of potential problems.
Improved standard of helidecks. In the early 1990s a series of helideck surveys by CAA on behalf of the Health and Safety Executive (HSE) led to the introduction of a formal helideck inspection regime administered by British Helicopter Advisory Board (BHAB).
Improved helideck operating standards. The UK Offshore Operators Association (UKOOA) Aircraft Committee led preparation of joint industry guidelines for the management of offshore helidecks in the early 1990s. First published in 1993, these guidelines are widely accepted as the UK industry standard and have been revised twice to embody the latest industry thinking.
Offshore flights restricted in poor weather conditions. Following the fatal accident at Cormorant Alpha in 1992, industry introduced operating policies to improve the management of helicopter operations in adverse weather conditions.
Helideck crews more competent. Training and competence of the helideck crews was challenged in the early 1990s, leading to industry jointly developing competence-based training requirements.
Focus on safe helidecks and helicopter operations. Since the early 1990s, HSE and CAA have turned greater focus toward offshore helicopter operations. An offshore helideck is a collection of systems, some of which are safety-critical. Owners and operators are required to list the safety-critical elements, subject them to independent review and develop a scheme for verification of their performance throughout the installation's lifecycle.
Since 1998, HSE has commissioned several studies into various aspects of offshore helicopter operations safety.
The introduction of crew resource management (CRM). Helicopter operators, in conjunction with CAA, have developed and introduced systems to improve CRM.
Progressively, since the late 1980s, multicrewing (all-instrument rated) has been introduced on UK offshore flights.
Ongoing activity
Some of these initiatives have been part of ongoing research into improving offshore helicopter flight safety, instigated by the HARP report and, subsequently, CAA's Review of Helicopter Offshore Safety and Survival report published in 1995. Other research projects have contributed to improving offshore helicopter flight safety.
Helideck motions on floating structures and vessels. Since 1992 CAA has commissioned a significant amount of research into the effects of the motion of floating platform and vessel helidecks on helicopters. With about half the offshore helidecks on the UKCS on moving structures and vessels, this routinely brings into focus the demands on pilot skills.
A new motion severity index (MSI) will better establish whether a helicopter can safely remain on a moving helideck. Work on establishing MSI-based operating limits for helicopters is nearing completion. Also, a joint industry group led by the International Marine Contractors Association and BHAB is revisiting motion limits for landing on moving helidecks set more than 20 years ago. The objective is to establish validity and look for a more scientifically based method of defining the parameters and limits that should be applied for landing in conjunction with the MSI limit.
Aerodynamic hazards around offshore platforms. A major research project funded by CAA and HSE reported in 1999 the nature and extent of environmental hazards around offshore helidecks, installations and vessels. Further work to establish better aerodynamic criteria for designing platform topsides layouts, setting appropriate helicopter operating limits and monitoring operations is nearing completion.
Helideck lighting. On an approach to an offshore helideck, the surrounding light pollution can make identification and acquisition of visual cues for landing very difficult. A new helideck lighting system is being refined in preparation for in-service trials.
Helicopter emergency flotation. This project is directed at practical improvements in the crashworthiness of flotation equipment to enhance post-crash and ditching survivability. The majority of fatalities in crashes onto water are due to drowning. From analysis of accident data, the ability of the helicopter to remain afloat at or near the surface has been determined to be the major factor in increasing occupant survivability. In an associated project, investigations into improving the stability of ditched helicopters has led to the concept of side-floating helicopters. In the event of capsize, the helicopter floats on its side rather than completely inverting. With this scheme an airspace retained within the cabin removes the time pressure for escape and ensures that some of the doors and windows that form escape routes remain above the water level, making it easier to get out. By fortunate coincidence, the additional flotation devices required for the side-floating scheme are a practical way of improving the crashworthiness of the system, providing increased flotation unit redundancy.
Preparation of a comprehensive helideck design manual. The Health & Safety Commission's Oil Industry Advisory Committee's Helicopter Liaison Group is spearheading this project. Sponsors and industry groups invited to participate include nine industry organizations and three regulators with interests in UKCS offshore helidecks. The manual is scheduled for publication in 2002.
Flight operations monitoring. Flight operations monitoring is a mature and well-established practice among several UK commercial airlines, with widely acknowledged safety benefits. Applied to offshore helicopters, it allows operators to identify and correct operational failures (for example, shortfalls in training or procedures) and obtain better information on operational difficulties caused by environmental factors such as weather and thereby minimize risks. Helicopter Operations Monitoring Programme trials were started in 1999, and up to September 2001, five offshore helicopters had been fitted with the system. The trials were so successful that, led by a UKOOA initiative, the industry voluntarily committed to full-scale implementation.
The future
Despite the reduction of offshore helicopter fatalities in recent years, there is no room for complacency. Nonfatal reportable accidents continue to occur on the UKCS, occasionally with serious injury inflicted. This highlights the real value to the oil and gas industry of continuing to pursue safety initiatives and research projects that will improve the safety of offshore helicopter operations. The key to maximizing payback is to ensure that each piece of work undertaken is based on sound operational need and is well executed.
Editor's note: At press time, Shell had suspended all flights with Sikorsky S76 helicopters while the company investigated how a routine crew-change flight resulted in a fatal crash July 16. Carrying 11 personnel, the Bristows-operated helicopter was flying between Shell's Clipper gas platform in the Leman gas field area and the Monarch. Shell has begun an inquiry into the cause alongside the CAA's Air Accident Investigation branch.

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