Credit to the pilots and crew. Credit to the people that trained them.

Now for some theories... some more speculative than others!

1. Contaminated fuel from Beijing. Underpaid ground staff and procurement officials in Beijing run a profitable side-line in substituting low-grade or diluted fuel. The engines have an assisted start and the high engine rpm during take off thrust and cruise was enough to maintain engine function throughout the flight. During landing the decreasing rpm dropped below a sustainable threshold and engines basically stalled. Insufficient time available to use the onboard emergency backup power to re-start the engines.

2. Dropping below 1000ft the 777 is within range of a large number of RF transmitters - local radio, PMR, pirate stations, taxi companies. Interference or spikes on the wired control system maybe caused a switch to a major power/fuel system, or maybe an emergency software/hardware re-set - taking 10's of seconds to re-boot - which is more than suficient to screw up a landing.

3. Software Bomb - hacked firmware in Beijing, or at last scheduled maintenance. Basically hack any software function executed as part of landing software suite. Not necessary to be a catstrophic software "bomb". As above - a simple sub-system re-set below 1000ft is pretty much guaranteed to precipitate a desperate glide over heavily populated areas.

4. The 777 was originally due to land, turn-around and head back to China carrying Gordon Brown. The fault was due to occur later in the day, somewhere over Siberia. Blame who you like - Al Qaeda (payback for UK "plausible denial" over extraordinary rendition via Prestwich?), FSB (pesky British Council being all "colonialy" and stuff?), or CIA (fill in your own conspiracy here - after all, they are the folks that have easy access to the 777 firmware!)

One thing is for sure, if there is any hint of a security loophole in Boeing's software of hardware, we won't get to hear about it. "National Security" will trump any public interest. So ignore all of the above - expect reports of avian impact or pilot error - much easier to report and most people will swallow it!

After all, if we happily accept that the Pentagon was hit by an aircraft that had no wings or engines and evaporated on impact - it should be simple to hide a firmware hack.

— Specul8