The crew of a commuter plane that fell out of the sky, killing all 49 people aboard and one person on the ground, noticed significant ice buildup on the wings and windshield just before the plane began pitching and rolling violently, investigators said Friday.
Officials stopped short of saying the ice buildup caused Thursday night's crash and stressed that nothing has been ruled out. But ice on a plane's wings can interfere catastrophically with an aircraft's handling and has been blamed for a number of major air disasters over the years.
It was the nation's first deadly crash of a commercial airliner in more than two years.
The twin turboprop aircraft -- Continental Connection Flight 3407 from Newark, N.J. -- was coming in for a landing when it went down in light snow and fog around 10:20 p.m. Thursday about five miles short of the Buffalo Niagara International Airport.
Flames Visible For Miles
Witnesses heard the plane sputtering before it plunged squarely through the roof of the house, its tail section visible through flames shooting at least 50 feet high.
"The whole sky was lit up orange," said Bob Dworak, who lives less than a mile away. "All the sudden, there was a big bang, and the house shook."
Two others in the house escaped with minor injuries. The plane was carrying a four-member crew and an off-duty pilot. Among the 44 passengers killed was a woman whose husband died in the World Trade Center attacks of Sept. 11, 2001.
Federal investigators found the black box recorders in the plane's tail that could shed light on what went wrong, but they said the smoldering debris was still too hot to remove bodies. The recorders were on their way to Washington for examination.
No Evidence Of A Mayday Call
No mayday call came from the pilot before the crash, according to a recording of air traffic control's radio messages captured by the Web site LiveATC.net. Neither the controller nor the pilot showed concern that anything was out of the ordinary as the airplane was asked to fly at 2,300 feet.
A minute later, the controller tried to contact the plane but heard no response. After a pause, he tried to contact the plane again.
Eventually he told an unidentified listener to contact authorities on the ground in the Clarence, N.Y., area.
Erie County Emergency Coordinator David Bissonette said it appeared the plane "dove directly on top of the house."
"It was a direct hit," Bissonette said. "It's remarkable that it only took one house. As devastating as that is, it could have wiped out the entire neighborhood."
The 74-seat Q400 Bombardier aircraft, also known as the Dash 8, in Thursday's disaster was operated by Colgan Air, based in Manassas, Va. Colgan's parent company, Pinnacle Airlines of Memphis, Tenn., said the plane was new and had a clean safety record.
Cause Not Yet Determined
The nearly vertical drop of the plane suggests a sudden loss of control, said William Voss, a former official of the Federal Aviation Administration and current president of the Flight Safety Foundation, a nonprofit advocacy group.
Voss suggested that icing or a mechanical failure, such as wing flaps deploying asymmetrically or the two engines putting out different thrust, might have caused the crash, he said.
After the crash, at least two pilots were heard on air-traffic control messages saying they had been picking up ice on their wings.
"We've been getting ice since 20 miles south of the airport," one said.
Ice on the wings of a plane can alter aerodynamics and interfere with lift and handling. The danger is well known among pilots.
In general, smaller planes like the Dash 8, which use a system of pneumatic de-icing boots, are more susceptible to icing problems than larger commuter planes that use a system to warm the wings.
The boots, a rubber membrane stretched over the surface, are filled with compressed air to crack any ice that builds up.
A similar turboprop jet crash 15 years ago in Indiana was caused by icing, and after that the NTSB issued icing recommendations to more aggressively use the plane's system of pneumatic de-icing boots. But the FAA hasn't adopted it. It remains part of the NTSB's most-wanted safety improvements list.
The National Transportation Safety Board sent a team of investigators to Buffalo. The Department of Homeland Security said there was no indication of terrorism.
Neighbor Hears "Tremendous Explosion"
While residents of the neighborhood were used to planes rumbling overhead, witnesses said it sounded louder than usual, sputtered and made odd noises.
David Luce said he and his wife were working on their computers when they heard the plane come in low.
"It didn't sound normal," he said. "We heard it for a few seconds, then it stopped, then a couple of seconds later was this tremendous explosion."
Dworak drove to the site, and "all we were seeing was 50- to 100-foot flames and a pile of rubble on the ground. It looked like the house just got destroyed the instant it got hit."
One person in the home was killed, and two others inside, Karen Wielinski, 57, and her 22-year-old daughter, Jill, escaped with minor injuries.
Karen Wielinski told WBEN-AM in Buffalo that she was watching TV in the family room in the back of the house when she heard a noise.
Woman In House: "The Ceiling Was On Me"
"Planes do go over our house, but this one just sounded really different, louder, and I thought to myself, 'If that's a plane, it's going to hit something,'" she told the station. "The next thing I knew the ceiling was on me."
She said her husband, Doug, was killed.
The plane was carrying 5,000 pounds of fuel and apparently exploded on impact, Erie County Executive Chris Collins said.
The 9/11 widow on board was identified as Beverly Eckert. She was heading to Buffalo for a celebration of what would have been her husband's 58th birthday, said Mary Fetchet, a 9/11 family activist.
Clarence is a growing eastern suburb of Buffalo, largely residential but with rural stretches. The crash site is on a street of older, single-family homes about 20 to 25 feet apart that back up to a wooded area.
Other Recent Crashes
It was the first fatal crash of a commercial airliner in the United States since Aug. 27, 2006, when 49 people were killed after a Comair jetliner mistakenly took off from a Lexington, Ky., runway that was too short.
The crash came less than a month after a US Airways pilot guided his crippled plane to a landing in the Hudson River in New York City, saving the lives of all 155 people aboard. Birds had apparently disabled both its engines.
On Dec. 20, a Continental Airlines plane veered off a runway and slid into a snowy field at the Denver airport, injuring 38 people.
Continental said relatives and friends of those on Flight 3407 who want to give or receive information about those on board can call a special family assistance number: (800) 621-3263.
Contributing to this report were Associated Press writers Carolyn Thompson in Buffalo, Linda Franklin in Dallas, Daniel Yee in Atlanta, Ron Powers in Washington, and Cristian Salazar and Jennifer Peltz in New York.