advanced C130 aircraft with special IR and cameras are part of the search.
one article indicates that the plane had survival gear aboard.
as to ELT's...if the plane were out in the open and it was on, they would have heard it
but if he was in a mountain pass...maybe not. terrain is different out here.
many sightings of old wrecks, one copter went out to check on one over a year old.
in the past, airliners didn't require ELT's as long as dispatch and radar were used to keep track of planes. even domestic USA we used to have to send position reports to dispatch a few years ago.
while area 51 is within the range of the plane, it might be unlikely that he went that far...but you never know.
if he was just using pilotage for nav, it would be easy to get lost.