akgo01, They could drift only because the ice was melting. And if they could drift, then they could sink. The ice was melting when it was warm.
The plane are made of aluminum and would lose their heat rapidly and would not sink as their temperature match that of the ice. Over the 50 years they would have been buried. Actually they landed on Greenland.
As far as moving,could be, but they didn't have G.P.S. back then and the pilot could have made a navigation error to Lat. Long. position,or the salvage operator .
Extract,http://p38assn.org/glacier-girl.htm
it was decided the squadron should turn back and head for BW-8, the airbase on the western side of Greenland from where this leg of the flight originated.
An hour later, they saw the east coast of Greenland and weather that would prove to be as bad or worse than they flew through earlier.
About 130 miles from the base the B-17s apparently received a message from BW-8 that said "Ceiling twelve hundred feet. Visibility one-eighth mile"
There is a map on this site where they crashed on Greenland, not on some ice flow.
