To give the pilot the benefit of doubt:

There was a series of fires that blew out all transponders and comm. The fire suffocates all crew and passengers. But the pilot is able to somehow survive the smoke and lack of air as he has special masks and hood. He is miraculously able to glide and land the plane on the ocean surface without any physical breakup of the plane.. Assuming somehow the landing was rough enough to physically knock out the pilot but not break up the plane. So no one is conscious.

How long would the plane float? Would any emergency beacons go off?
If the plane sinks intact to the bottom of ocean, would any beacons go off even if the FDR is not exposed to water? And if no beacon and the plane is intact, could not one of the Navy ships or submarines be able to identify it through a big hunk of metal using sonar profile?

And let's assume someone is conscious once the plane is floating on the water.. How difficult would it be to open one of the doors? Would it be a challenging task if one was weak...??

I ask these questions to see if we can eliminate a possible scenerio, not meant to speculate or anything as such.. Thanks for the insputs