Although the second article says the crash occurred above the tree line, the local paper here in Calgary published a photograph of the crash site that showed clearly there were a large number of evergreen trees nearby (in fact, the aircraft appears to have collided with a large tree near the end of its run). So a knife or saw would have probably enabled them to build some sort of shelter, and a mag-flint block would have enabled them to get a fire going, which might have saved the life of the third survivor. (I'm betting they laid him on the bare ground instead of ripping down some pine boughs to insulate him.)