AIR accident investigators said last night that the crew of the plane that crashed in New York state killing 50 people had noticed "significant ice build-up" on the wings and windshield before the tragedy.
Steve Chealander, spokesman for the National Transportation Safety Board, also said initial analysis of conversation from the plane's cockpit voice recorder revealed the crew went through a "severe pitch and roll problem" as the aircraft began its approach to Buffalo airport.
• Click here to listen to a recording of the conversation between air traffic control and the pilot of Flight 3407
The crew had reported that snow and mist were affecting visibility at 16,000ft and requested permission to drop to 12,000ft and then 11,000ft.
One of the cockpit crew was heard saying: "We've been getting ice since 20 miles south of the airport."
The plane's cockpit voice recorder containing two hours of conversation and the data recorder were both said to be in "excellent" condition and were sent for analysis to a lab in Washington.
Mr Chealander said that the FBI were appealing for more information and that investigators were "not ruling anything in or anything out at this stage."
Eyewitnesses described a "mini-earthquake" as Continental Connection Flight 3407 nose-dived into the house in a small upstate town near Buffalo minutes before it was due to land.
The explosion, which sent flames 100 feet into the night sky, killed all 44 passengers, four crew and an off-duty pilot.
Douglas Wielinkski, 61, who was in the house when the aircraft came through the roof, also died. His wife, Karen, 57, and their daughter, Jill, 22, escaped with minor injuries.
Among the passenger victims was Beverly Eckert, whose husband died in the 9/11 attacks on the World Trade Centre.
The Department of Homeland Security said there was no reason to believe the crash, which took place at about 10:20pm on Thursday local time, was linked to terrorism.
Coming less than a month after New York narrowly avoided tragedy when a US Airways jet was forced to ditch in the Hudson river, this was the first fatal incident involving a commercial airliner in the US for two-and-a-half years.
The 74-seater plane crashed in Clarence, which one resident described as "small town USA" – about five miles from Buffalo Niagara airport.
Police said it was "amazing" that only one house was damaged, and firemen said the crash could have wiped out an entire neighbourhood.
Air traffic controllers received no mayday or warning that the flight from Newark, New Jersey, to Buffalo, which had been cleared for landing, was experiencing difficulties. The twin turboprop plane, operated by Continental Connection's regional partner, Colgan Air, disappeared from radar at an altitude of 2,300ft in light snow and fog before plummeting into the roof of the house.
Clarence residents reported hearing unusual noises from the plane before it went down, including "loud spluttering". Tony Tatro,who was driving home when the plane passed about 75 feet overhead, said its nose pitched lower than normal and its wings tilted. It crashed moments later, he said.
"I know what a normal plane sounds like and this didn't sound normal."
There have been safety concerns about the model, the Bombardier Dash 8 Q400, in recent years. Scandinavian Airlines withdrew its fleet after there had been three crash landings.
David Learmount, a former turboprop pilot and an expert on aircraft safety, said the Q400 has a de-icing system but added: "If ice forms on the wings, the wings change shape, and the plane simply stops flying. Whatever happened, happened quite suddenly."
Kieran Daly, editor of the aviation news website Air Transport Intelligence, said turboprop planes were as safe as jets, but faced disadvantages in icy conditions. He said: "Pilots cope by increasing altitude – icing mainly occurs at lower levels – but because propeller-driven planes are slower, they take longer to reach high altitude and spend longer in the icy conditions."
Barack Obama, the US president, expressed his condolences, saying: "Our hearts go out to the families and friends who lost loved ones."
Crash victim was widow of man who died on 9/11
ONE of the victims of the New York plane crash was the widow of a man who died in the terrorist attacks on 11 September, 2001.
Beverly Eckert, 57, was flying to Clarence for a celebration of what would have been the 58th birthday of her husband, Sean Rooney, and was to go to the presentation of a scholarship in his name at Canisus High School, where they met.
Only last week, she had been at the White House as part of a delegation of families of victims of the attacks to discuss terrorism policies. Barack Obama, the US president, said yesterday she was "an inspiration to me and so many others".
Carie Lemack, whose mother died on one of the hijacked planes, said: "I'm in shock, I just can't believe it. Beverly had a can-do attitude about everything, and she never gave up."
Mr Rooney was working in the World Trade Centre in Manhattan when terrorists flew two planes into it. The couple spoke by phone just before he died. Mrs Eckert later recalled: "I said: 'It doesn't look to me like they're going to be able to rescue you.' I said: 'Sean, we need to say goodbye', and we did.
"He was still breathing and saying: 'I love you', and coughing. I heard an explosion and a whoosh. I walked into the TV room and saw the building collapse. I knew he was gone."
Flybe to carry on with Q400 fleet despite crash
FLYBE, the British airline which has the world's largest fleet of the type aircraft involved in the New York crash, said yesterday it would be operating the planes as normal.
Flybe has 49 of the Bombardier Dash 8 Q400 aircraft, which it uses for domestic and short-haul routes, including flights out of Edinburgh, Glasgow and Aberdeen. In a statement, the company said: "We have been in contact with the Civil Aviation Authority during the course of the day, who are completely satisfied with the Flybe Q400 fleet which we continue to operate as normal.
"Flybe can confirm that its Q400 fleet has flown more than a third of a million flights without any serious incident."
In recent years, increasing numbers of regional airlines operating shorter routes of 500 miles or less have replaced jets with propeller-driven aircraft such as the Q400, which fly almost as fast as jets. They use around 30 per cent less fuel.
The Q400 had its first flight in 1998 and entered commercial service in February 2000.