You'd imagine that the transponder going out would immediately bring up a fault warning in the cockpit, though, even if the fire itself had somehow not been detected. But I suppose a sufficiently bad bug in the flight systems might be invoked to cover that.

If so, they would probably already have seen other faults as well, and at the very least have a warning about the transponder being disabled. Their last communication made no mention of any problems.

So, is there a publically traded company that makes fireproof transponders? Because I have this hunch...