Helicopters Magazine

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De-Risking Ditch-Drowning

April 28, 2014  By Rick Adams

"I felt my brain screaming for oxygen.” “The pressure of the water caused a stabbing pain in my eyes and ears.” “Your body is a mass of pain and you know you are dying.”

"I felt my brain screaming for oxygen.” “The pressure of the water caused a stabbing pain in my eyes and ears.” “Your body is a mass of pain and you know you are dying.”

That’s how some near-drowning victims describe the excruciating experience of what is essentially suffocation by submersion in water. Hardly the peaceful “drift into bliss” portrayed in movies such as Titanic.

In an offshore helicopter accident, if the crash does not kill you, the sea may finish the job. Drowning is the leading cause of death following a helicopter ditching.

Stig Severinsen, free-diving world champion from Denmark, has held his breath underwater for 22 minutes, but for most of us the typical breath-holding time is perhaps 30 to 45 seconds in warm 25-degree Celsius water. When the water temperature drops below 15 degrees, the average breath-hold time decreases rapidly, and in near-freezing water can be as little as 5 to 10 seconds. Considering that it takes 30 to 90 seconds just to escape from a helicopter submerged in the brine, the odds of surviving a water impact are slim indeed.


The water temperatures in the North Atlantic, by the way, average 12 to 14 degrees in summer and a bitter 1 to 2 degrees in winter.

Fully five years after 17 people drowned off the Newfoundland coast when Cougar 491 sank in about 150 metres of water, and more than three years after recommendations by the Transportation Safety Board, Transport Canada (TC) has new safety regulations focused on both preventing and surviving water ditchings.

Two of the new measures focus on crew and passenger survivability – requiring each occupant to wear water immersion survival suits and to have emergency breathing equipment.

The fluorescent orange or yellow survival suits are designed to prevent hypothermia from immersion in cold water, and are therefore made of neoprene rubber, usually with built-in boots, built-in gloves or watertight wrist seals, and a hood.

The underwater emergency breathing apparatus – UEBA (rhymes with SCUBA) – is carried on the suit, and provides an additional capacity of breathable air, enough hopefully to fill the gap of time it takes to escape a submerged aircraft and the time your breath-hold gives out. The offshore oil and gas industry in Canada had already made UEBAs mandatory in 2009.

Transport Canada did not go as far as the U.K. Civil Aviation Authority (CAA), which recently issued a “Safety review of offshore public transport helicopter operations in support of the exploitation of oil and gas.” (jointly with the Norwegian CAA). The review came in the wake of five North Sea accidents in four years. The CAA wants each oil worker being transported to and from offshore oil rigs to be seated next to push-out window emergency exits – which means workers must be small enough (in survival suits?) to fit through the opening. This will both reduce the number of passengers in a helicopter and possibly preclude some larger workers from commuting to their jobs.

The U.K., CAA and TC now prohibit flights when weather and water conditions make ditching in water a high-risk option. Environment Canada says the waters off Newfoundland exceed Sea State 4 (considered “moderate” with wave heights up to 2.5 metres on the Douglas Sea Scale) about half the time year-round, but more than 80 per cent of the time in winter. Sea State 6 (“very rough” with waves up to 6 metres) occurs 8.9 per cent of the time between December and January. The highest is SS9 – waves over 14 metres and with the somewhat understated condition of “phenomenal.”

TC, the U.S. Federal Aviation Administration (FAA), and the European Aviation Safety Agency (EASA) now certify Sikorsky’s S-92 aircraft emergency flotation system (EFS) to Sea State 6 conditions. The EFS is intended to keep the helicopter upright until occupants can escape in life rafts.

Training, of course, can also increase the odds of survival. In addition to UEBAs, Canadian Association of Petroleum Producers require a five-day program designed to help rig workers react effectively to water emergency situations, plus a safety briefing prior to each flight.

Crews also have access to an enhanced Helicopter Underwater Escape Trainer (HUET) to simulate escape techniques from a submerged or partially submerged helicopter.

Rick Adams is Chief Perspectives Officer of AeroPerspectives, an aviation communications consultancy based in the south of France. He has been writing about technology and training for 30 years.


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