Hmm..looking by air could they really see footprints from the side of a road then perhaps only a short distance into the trees? Would the snow really be so uniform and pristine that they could see from a helicopter that there were no tracks, even several miles perhaps, down the road? I could see if they were looking for a person from the helicopter but not footprints. Just thinking out loud here.
That's what I was thinking because I was under the impression that the showbanks on the sides of the road were fairly tall.
John Scarinza was involved in investigating this case and Renner interviewed him. There are some details concerning the helicopter search in a posting from January 8 2012.