There have been a number of accidents where aircraft have impacted the water in an uncontrolled manner, the flotation equipment has survived the impact but has not been manually activated by the crew. Research carried out by Westland Helicopters in the UK and independently in the USA on behalf of the FAA has identified drowning to be the major cause of loss of life. Aircraft occupants having survived the initial impact then failed to safely escape from the hull.
In March 1992, an AS332L crashed into Sea State 7 conditions during an offshore night flight. Only 6 of the 17 occupants survived. Although the impact was severe, post crash investigation indicated that the flotation system may have survived and been at least partially available, had it been activated. The crew did not have time to manually activate it and there was no automatic means. The accident investigators considered that inflated flotation bags would have prevented the hull from rapidly sinking and assisted passenger evacuation from the inverted cabin by allowing it to float higher in the water.
In September 1996, an AS350B1 was carrying out low level overwater filming with 2 persons on board. For reasons unknown, but suspected to be inadvertent closure of the fuel control lever, rotor rpm dropped and the aircraft descended into the sea. Although the pilot attempted to, he did not have enough time to manually activate the emergency flotation equipment. The helicopter impacted the sea, inverted with the subsequent loss of the passenger.
Provision of a means to automatically inflate both ditching and emergency floatation equipment could have prevented loss of life in the above accidents.
Most helicopters working offshore in the North Sea now have automatic inflation of floats.