Descending through a snowy mist toward Buffalo Niagara International Airport on Thursday evening, the crew of a Continental commuter flight noticed ice buildup on the windshield and wings of the airplane, despite having turned on the craft’s de-icer.
Then after the pilot put the wing flaps down in preparation for landing, the plane lurched into “a series of severe pitch and roll” movements and plunged to the ground, said National Transportation Safety Board spokesman Steve Chealander on Friday.
The 74-seat Q400 Bombardier aircraft, a turboprop also known as a Dash 8, crashed on the roof of a home in the quiet Buffalo suburb of Clarence Center, killing all 49 people aboard and one on the ground.
On board the flight from Newark, N.J., were 45 passengers, including the winner of a MacArthur “genius grant,” the widow of a 9/11 victim, two members of a prominent jazz band and the cantor of a Jewish congregation. The flight had a crew of four.
Federal authorities said it was premature to speculate on the cause of the crash.
“We’re not ruling anything in or anything out at this point,” Chealander said.
But his remarks made it clear the investigation would focus on whether Continental Connections Flight 3407 was brought down by the destabilizing effect of ice on the wings.
Remarkably, destruction from the crash was almost entirely limited to the modest parcel where the plane came down, obliterating the house, which was instantly engulfed in a ball of fire, but leaving surrounding houses in the rolling, wooded area about six miles northeast of the airport virtually untouched.
The plane that crashed Thursday was only 8 months old, according to the Federal Aviation Administration. Since 2004, aircraft of its type have not been involved in any accident caused by mechanical failure, NTSB records show.
At the NTSB briefing, Chealander described the final minutes of the flight, based on data and conversations preserved on the plane’s two “black box” recorders.
He said the crew discussed the snowy, misty weather, with visibility reduced to three miles.
“That’s icy conditions,” Chealander said.
At an altitude of 16,000 feet, they commented on how hazy it was and asked to descend to 12,000 feet. They were cleared to descend to 11,000 feet.
The crew discussed the ice buildup on the windshield and the leading edge of the wings, which Chealander said could be “an aerodynamic impediment.” The flight data recorder indicated that the de-icer was turned on, though the NTSB hasn’t yet determined whether it was functioning properly.
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One minute before the end of the recording, the crew put down the landing gear; 20 seconds later, they adjusted the flaps in preparation for landing. Within seconds, the plane began to pitch and roll. Immediately before the end of the recording, the crew attempted to raise the landing gear and flaps.
Icing is not unusual for planes flying through inclement weather. Several planes that were behind the Continental flight reported icing but landed safely.
“Ice per se is not much of a concern,” said Hans Weber, an aerospace consultant and former chair of an FAA safety advisory panel. “It’s really about where and how much.”
Early reports suggested the plane banked to the right then continued to turn right almost 180 degrees before disappearing from the radar, Weber said.
That could be a sign of stalling, which could result from icing, Weber said. He added: “But that’s just one possible scenario.”
The aircraft was fitted with electrical de-icing systems, including rubber bladders along the wings’ front edges that expand and break off ice, allowing it to fall away.
Controversy has surrounded these 1920s-era systems since an American Eagle ATR-72 crashed on Oct. 31, 1994, near Roselawn, Ind., after flying for a prolonged period in icy conditions. After the accident, which killed 68, the NTSB recommended that the FAA require manufacturers to test aircraft with these systems to determine whether they were susceptible to ice buildup.
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