Half a century after Northwest Airlines Flight 4422 slammed into the side of 4,950-meter Mount Sanford in eastern Alaska's Wrangell Mountains, killing all 30 men on board, commercial pilots Kevin McGregor and Marc Millican found the wreckage embedded in a glacier.

The debris had been quickly covered by snow and ice at the time and so had never been recovered. McGregor and Millican studied maps and historical accounts to calculate where on one of several glaciers they thought the impact had occurred. Then they estimated how far the debris field might have traveled as the glacier moved down the mountain. Because their searches from the air revealed nothing, they undertook several dangerous treks up onto the glacier to see if they could find what was left of the plane.

On one of their visits to the site after locating the wreckage, they found a severed human arm complete with its hand embedded in the ice. View this audio slide show to hear McGregor talk about the quest while viewing photos taken during the climbs to find the wreckage of NW 4422.

» Watch the audio slide show