Wreckage crews have recovered both Pratt & Whitney PW150 engines of the Colgan Air Q400 that crashed outside Buffalo last Thursday, and preliminary inspection shows a condition “consistent with high-powered flight” when the airplane hit the ground, according to NTSB member Steven Chealander. Meanwhile, Chealander said the NTSB will send questionnaires to “every pilot that flew that night” in the Buffalo area to try to find conditions that could have led to such a violent upset. That, he added, would take several weeks, and the investigation, in total, up to a year.
Operating as Continental Connection flight 3407 from Newark, N.J., to Buffalo Niagra International Airport, the 74-seat turboprop carried 45 passengers and four on-duty crewmembers when, after the airplane descended to about 2,300 feet, air traffic control lost contact with the pilots. FDR data shows that the Q400 pitched up at an angle of 31 degrees, then down to 45 degrees, followed by a 46-degree roll to the left, then a 105 degree roll to the right. The airplane fell the last 800 feet in five seconds, before crashing virtually flat onto a single house in the suburban town of Clarence Center, N.Y., killing one of the residents. Two other residents escaped with minor injuries.
The crew observed “significant” ice accretion on the aircraft’s windows and wings prior to the eventual upset that led to the crash. The airplane’s flight data recorder indicates that the airplane’s autopilot did not disengage until the stick shaker activated, however, and airmets for the Buffalo area indicated no worse than moderate icing. In fact, only 27 minutes after the accident another Colgan Q400 flew to Buffalo from Newark on virtually the same flight path, said Chealander.
Apart from airmets for light and moderate icing, the National Weather Service issued a sigmet for turbulence that night in the Buffalo area, said Chealander. He also noted that a pirep indicated severe icing over Dunkirk, N.Y., some 50 miles southwest of Buffalo.
Along with a recommendation that pilots turn on leading-edge deicing boots as soon as they encounter icing, a December 18, 2008 safety alert issued by the NTSB said they should “turn off or limit the use of the autopilot in order to better ‘feel’ changes in the handling qualities of the airplane.” Chealander wouldn’t characterize the pilots’ failure to disengage the autopilot as necessarily improper, however. In fact, only when the airplane encounters “severe” icing must flight crew disengage the autopilot, according to the Bombardier Q400 Aircraft Flight Manual (AFM).
The flight’s captain, Marvin Renslow, had flown more than 3,379 hours in his career, but only 110 hours on the Q400. First Officer Rebecca Shaw had accumulated 2,244 hours, 774 hours of which she flew on the Q400 for Colgan.