Originally Posted by Rock Sexton
Again, in the movie they tell you why that is. The assistant in Stark's ship says they can't find a trace of the energy from the cube anywhere else so they had no other beacon to finding him. Although Stark says, "keep looking" .... we also see that the wing is sinking deeply into the ice.
Right. They were able to trace the Cube's energy. They expected to find the Cube with the plane. That's why it was significant that the Cube fell out so long before the plane actually crashed.
No satellites to help pinpoint the crash location, in the 40s. Even with satellites today, and other advanced technology, there are a surprising number of plane crashes on land that aren't located for a very, very long time.
At the start of the movie, they also lampshade this -- I think one of the arriving SHIELD agents (if that's who they are) says something like, "Why wasn't this found before?", and the guy who was there to greet them responds with, "this landscape is changing all the time".
Not only did the ending show the Wing settling/melting into the ice, but snowstorms would have soon covered all of the wreckage and the scars of the crash.