Pilots knocked out by nerve gas

During a landing approach, both the captain and co-pilot of a Braathens airliner were completely incapacitated by a toxic gas on the flight deck.

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(Dagbladet.no:) Flight BU925 between Stockholm and Malmö was saved by the fact that it was still a few thousand feet above ground when Captain Niels Gomer and his co-pilot were completely incapacitated by a mysterious toxic gas. Otherwise the aircraft would probably have crashed with 73 people on board.

“There’s no doubt that this was the worst thing I’ve experienced in my whole life. Once I began to feel ill, things happened extremely quickly. If I hadn’t managed to get my oxygen mask on in 15 seconds, I would never have succeeded in getting it on. I was so ill that I couldn’t even lift an arm,” says Niels Gomer to Dagbladet.

According to the airline captain he was frightened to death every time he flew for a whole year after the accident, and he does not hide the fact that the incident could have had fatal consequences.

Didn’t notice anything
“If we had been closer to the ground when my co-pilot and I became incapacitated, things could have gone seriously wrong. The aircraft could not have landed itself,” says Niels Gomer.

The worst of it for him was that they didn’t know what was happening to them.

“An engine fire, for example, is something specific which we have been trained to handle, but we had never heard of anything like this, and didn’t realise that we were being intoxicated before we were really ill. My first thought was “We’re going to die here – all 73 of us,” says the captain to Dagbladet.

Following a number of alarming incidents in international air traffic since the 1980s related to toxic gasses in cabin air, British and Australian authorities in particular are putting strong pressure on the airline industry (see box).

Contaminated cabin air

The route flown by the Swedish aircraft was operated by Norwegian-owned Braathens Malmö Aviation AB.

It was on the last of three flights between Stockholm and Malmö on Friday 12 November 1999 that Captain Niels Gomer and his co-pilot suddenly became so ill that they no longer had control over the BAe 146 machine.

Within a period of a few seconds, both were struck by severe dizziness and nausea. Although both put on oxygen masks, the captain continued to experience the symptoms.

Fortunately the co-pilot revived quickly enough to get the aircraft, with 73 people aboard, safely down to earth.

The cabin crew of the Swedish aircraft had already noticed that something was wrong with the cabin air during the two earlier flights between Stockholm and Malmö.

Resembled zombies
Both the cabin personnel and the 68 passengers on board were severely affected by the unknown toxic gas after landing. All the passengers were remarkably subdued and some were asleep.

“Several of them were tired and had itchy skin. Others were so deeply asleep that it was difficult to wake them up,” says Captain Gomer.

Olle Lundström, an accident investigator, now retired, investigated the incident with his colleague Henrik Elinder.

“Of course the situation is serious when both pilots are incapacitated at the same time. This represents a safety hazard,” says Elinder, who led the technical investigation of the airliner, to Dagbladet.

“According to the crew, several of the passengers were in a zombie-like condition,” states aircraft accident investigator Olle Lundström.

Oil leak
During the thorough inspection of the aircraft after the near-accident, the Aircraft Accident Investigation Board did not find either mechanical faults or traces of toxic chemicals.

Nevertheless, the Swedish accident investigation board concluded that contaminated cabin air was probably the cause of the near-accident.

The investigators indicate that an unidentified toxic gas was probably formed after an oil leak in an engine and found its way into the cabin air.

Nerve gas

The turbine oil in aero engines contains chemical substances which can develop into compounds resembling nerve gas at high temperature.

Halvor Erikstein, an industrial hygienist in the Norwegian Federation of Oil Workers (OFS), has learned a lot about how dangerous these toxic chemicals can be:

“In the event of strong heating, chemical compounds can be formed which act as nerve gasses similar to those developed for chemical warfare. It is believed that this can have contributed to the poisoning of airline crew members,” says Erikstein to Dagbladet.