In a careful worded update today, The National Transportation Safety Board clearly indicated that pilot error, not wing icing, was probably the cause of the crash of Continental Airlines flight 3407, operated by a regional-airliner subcontractor, Colgan Air, in which 50 were killed on February 12.
The crash occurred as the plane, a Bombardier Dash8-Q400 turboprop, went out of control while on approach to the airport in Buffalo that night.
"The circumstances of the crash have raised several issues that go well beyond the widely discussed matter of airframe icing" said the NTSB acting chairman, Mark V. Rosenker. The preliminary investigation shows that while icing conditions may have been present, the aircraft's de-icing system was working properly and that tests show that "icing had a minimal impact on the stall speed of the airplane," he said.
Instead, the plane appears to have spun out of control when whichever of the two pilots had the controls responded incorrectly to a "stick shaker" signal on the yoke by pulling the nose up sharply -- a mistake that put the aircraft out of control. Seconds later, it crashed.