Given the continuing absence of any evidence for more esoteric/sinister theories 11 days after the disappearance of FL370, this account seems increasingly plausible:
The left turn is the key here. Zaharie Ahmad Shah1 was a very experienced senior captain with 18,000 hours of flight time. We old pilots were drilled to know what is the closest airport of safe harbor while in cruise. Airports behind us, airports abeam us, and airports ahead of us. They’re always in our head. Always. If something happens, you don’t want to be thinking about what are you going to do–you already know what you are going to do. When I saw that left turn with a direct heading, I instinctively knew he was heading for an airport. He was taking a direct route to Palau Langkawi, a 13,000-foot airstrip with an approach over water and no obstacles. The captain did not turn back to Kuala Lampur because he knew he had 8,000-foot ridges to cross. He knew the terrain was friendlier toward Langkawi, which also was closer.
Take a look at this airport on Google Earth. The pilot did all the right things. He was confronted by some major event onboard that made him make an immediate turn to the closest, safest airport.
For me, the loss of transponders and communications makes perfect sense in a fire. And there most likely was an electrical fire. In the case of a fire, the first response is to pull the main busses and restore circuits one by one until you have isolated the bad one. If they pulled the busses, the plane would go silent. It probably was a serious event and the flight crew was occupied with controlling the plane and trying to fight the fire. Aviate, navigate, and lastly, communicate is the mantra in such situations.
There are two types of fires. An electrical fire might not be as fast and furious, and there may or may not be incapacitating smoke. However there is the possibility, given the timeline, that there was an overheat on one of the front landing gear tires, it blew on takeoff and started slowly burning. Yes, this happens with underinflated tires. Remember: Heavy plane, hot night, sea level, long-run takeoff. There was a well known accident in Nigeria of a DC8 that had a landing gear fire on takeoff. Once going, a tire fire would produce horrific, incapacitating smoke. Yes, pilots have access to oxygen masks, but this is a no-no with fire. Most have access to a smoke hood with a filter, but this will last only a few minutes depending on the smoke level. (I used to carry one in my flight bag, and I still carry one in my briefcase when I fly.)
What I think happened is the flight crew was overcome by smoke and the plane continued on the heading, probably on George (autopilot), until it ran out of fuel or the fire destroyed the control surfaces and it crashed. You will find it along that route–looking elsewhere is pointless.
If this theory is correct, it seems unlikely that the plane and its flight data recorder will ever be found. The search for Air France 447 suggests that it’s basically impossible to find the fuselage of a plane in the deep ocean unless searchers know almost exactly where the plane went down (Flight 447 was found 6.5 miles from its last known location two years later, after three previous failed searches). Any debris spotted at this point will be hundreds of miles from the crash site. Reconstructing the path of such debris along ocean currents might confirm or dis-confirm the autopilot theory, however.