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Ice caused BA jet crash

The BA plane that crashed at Heathrow in January was probably brought down by ice in its fuel system, an accident report says.

The pilots of the Boeing 777 managed to land so that the 136 passengers and 16 crew escaped without serious injury.

The Air Accident Investigation Branch believes the flow of fuel dropped causing the engines to lose power less than a minute before touchdown.

But investigators say they still do not know how the ice could have formed.

Water is naturally present in aviation fuel and the investigators believe there may have been as much as five litres within this aircraft's fuel load.

But the report says levels of water found in fuel recovered after the 17 January crash were very low for a Boeing 777.
How accident unfolded

They dismissed the suggestion that the fuel itself froze or became "waxy" as icing occurred.

The report says the plane flew through unusually cold air over Siberia while en route from Beijing to Heathrow.

The fuel temperature fell to -34C (-29F). But jet fuel should not freeze until it is at less than -57C (-70F), and the report says the temperatures involved were not "unique".

The investigation into the crash of flight BA38 continues with testing at Rolls-Royce in Derby, and Seattle in the US, the home of Boeing.

Following Thursday's report, a spokesman for the US Federal Aviation Administration said it would be issuing an air-worthiness directive to US carriers operating Boeing 777 aircraft.

This was likely to be about "changes in procedures for pilots to follow in certain cold weather conditions" as well as "changes in certain fuel procedures on the ground", he said.

While it would not be an emergency directive, it was likely to be issued within 24 hours and would have immediate effect.

Fuel and water

Water in aviation fuel can be dissolved at the molecular level, or simply float as free water, suspended in the fuel. As the fuel gets colder tiny droplets can form and freeze.

The mystery facing investigators is why this might have happened on an apparently fully functioning aircraft.

Water in the fuel is controlled by draining it regularly out of the fuel tanks - and on the Boeing 777 a so-called "scavenge system" pumps it out.

Ice can form when the fuel temperature drops to around -1C (30.2F) to -3C (26.6F) Generally the ice crystals simply float and drift in the fuel without causing harm. The BA plane that crashed at Heathrow in January was probably brought down by ice in its fuel system, an accident report says. ... more

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