On the evening of February 12, 2009, Colgan Air Flight 3407 was on final approach to Runway 23 at the Buffalo Niagara International Airport in Buffalo, New York. It was dark, it was snowing, it was windy and the pilots had noted the accumulation of ice on the wings and windshield of the 78-seat regional airliner. Still, the pilots were not under undue stress as the cockpit voice recorders indicated a casual, unhurried atmosphere, there was even some unrelated chit-chat on the flight deck. Then, just moments before landing, air traffic controllers noticed the plane was no longer on their radar screens. Flight 3407 was down for reasons unknown.In the post-crash investigation, the most likely cause of the crash – the weather (including the snow, the wind and the ice) was quickly dismissed. If not the weather, then what happened to Colgan AIr Flight 3407 that caused it to fall out of the night sky and claim the lives of all on board and one on the ground?