New York State Plane Crash May Have Been Caused By Icy Weather

US air accident investigators are expected to examine the role played by freezing weather conditions as they begin the task of trying to find out what caused flight 3407 to crash in Buffalo, New York, last night.

It has emerged that there were safety fears over the model of plane involved in the crash. The propeller-powered Q400 built by the Canadian engineering firm Bombardier was temporarily withdrawn from service by the Scandinavian airline SAS in 2007 after a crash-landing in Copenhagen. It is the first fatal accident involving the Dash 8 Q400 series, which came into service in 2000 with an estimated 215 in use around the world.

However, the aircraft safety expert David Learmount, a former turbo-prop pilot, said there were no serious safety concerns over the Q400 and the problems with the SAS fleet were largely related to maintenance issues.

Learmount, a Flight International magazine editor, said the freezing conditions at the time of the crash, and the fact that it happened at night, would be investigated by officials from the US National Transportation Safety Board.

"It was cold, snowing and dark but these planes are designed to fly in icy conditions," Learmount said. "However, those conditions can be very fickle and if ice builds up on a plane it can be very difficult.

"At this time of year, when a pilot crashes approaching an airport that they will know well, the first thing you look at is the weather."

The 74-seat plane was being operated by Colgan Air on behalf of Continental Airlines. It was flying from Newark Liberty International airport, in New Jersey, to Buffalo Niagara International airport in light snow, fog and 17mph (27kph) winds.

The Bombardier Q400 series has a de-icing system on the tips of its wings that pumps air through the wing edges, creating a vibrating surface that prevents ice from building up. Learmount said any failure in this system would destabilise the aircraft rapidly.

"If ice forms on the wings, the wings change shape and the plane simply stops flying."

He said that when a plane succumbed to ice, one engine normally stalled first, causing a single wing to dip. According to one eyewitness, "the left wing was a little low" shortly before the crash.

On a recording of Buffalo air traffic control's radio messages just before the accident, the voice of a female pilot on flight 3407 can be heard communicating with air traffic controllers and does not appear to register any concern as she is asked to fly at 2,300ft (700 meters). A minute later, the controller tries to contact the plane but receives no response.

"Whatever happened, happened quite suddenly," Learmount said.

The investigation is likely to be complicated by the fact that any ice that may have contributed to the crash will have melted on impact, leaving investigators with the task of identifying the cause by a process of elimination if ice was the main factor.