1. Why no "MAYDAY" call? Perhaps it was given and no one heard it?
2. I think pilots in the cockpit have emergency oxygen masks with bottled oxygen that would allow them to operate even with smoke in the cockpit.
3. If the pilots were incapacitated and the plan on autopilot, why did it climb to 45,000 feet and then dive? It should've continued on the same path and altitude.
Oh well, this has given the 0bama regime some cover for their foreign policy blunders (Ukraine and Venezuela - when was the last time you heard about Venezuela?), but American's attention spans are growing shorter, so it's time to move on.
...if the fire began in the communication circuits they could have burnt up and unable to transmit.
My guess is that the transponder may have gone dark on the instrument panel as the first hint of problems. By now the circuits are frying and radio is inop. First is realized and flight is neglected as an attempt to fight the fire. The plane climbs and stalls, plunging to lower altitude where control is regained and plane is turned around for emergency landing. Autopilot is set to continue battling fire. In short order, crew and passengers overcome by toxic fumes. Aircraft continues flying on autopilot, maybe even losing altitude the entire time until it descends into the Indian ocean.