DAVID LEARMOUNT / LONDON
Dire weather and difficult conditions for helicopter oil-support operations in the North Sea have taken their toll over the years. But new safety equipment, technology and operating techniques have been developed - and are still being developed - that have improved helicopter safety and oil-support operations all over the world.
Between 1976 and 1992 the UK Civil Aviation Authority recorded eight fatal helicopter accidents, classifying four of them as "non-survivable". Three of those were attributed to serious mechanical failure, one to operational causes. Since 1992 there has been one fatal event in the North Sea - in July this year - and several non-fatal accidents or incidents; so not only has the fatal accident risk reduced, the survivability rate has also improved. The accident in July was non-survivable and followed a main rotor blade separation. The accident investigators' interim bulletin suggests it may have been due to undetected damage believed to have been caused by a lightning strike several years ago.
The hard lessons of the North Sea have produced the now globally accepted health and usage monitoring system (HUMS) for identifying component faults and stresses before they fail. In 1976 it was not a standard requirement, as it is now, for passengers flying to and from North Sea rigs to wear immersion suits.
A March 1992 crash at the Cormorant Alpha platform in high winds became a turning point for offshore helicopter operations safety. Recommendations from the UK Air Accident Investigation Branch following the accident, in which 11 people died on what would have been a 2min flight between neighbouring rigs, spawned the CAA's Review of Helicopter Offshore Safety and Survival (RHOSS) research programme. First published in 1995, there have been two subsequent editions. The horror of Cormorant Alpha was that the helicopter's impact with the sea was survivable, but five passengers died through failure to escape from the helicopter, and six died from hypothermia in the sea despite immersion suits and lifejackets, and despite their proximity to the two rigs. The RHOSS said of Cormorant Alpha and the other accidents studied: "The 19 fatalities in survivable accidents gave a general indication of the scope for saving lives through improvements to the safety and survival system."
The CAA is sponsoring research on rig helideck design and the dangers specific to flying in the vicinity of rigs on approach or departure.
Source: Flight International
