[rosswilson]

Read about Nigeria Airways Flight 2120 (http://en.wikipedia.org/wiki/Nigeria_Airways_Flight_2120).

An under-inflated tyre caught fire during take-off, the plane took off unaware of the fire, when the landing gear was retracted the fire spread burning through electrical and hydraulic lines.

A fire "outside of the pressurised part of the fuselage" doesn't mean the same didn't happen here.

[VolatileVoid]

Sure, although the NationAir DC-8 tragedy was a different jet. The 777 is significantly more advanced and I believe has some sort of fire detection in the wheel well; they would have known very shortly after takeoff if there was smoke. Unless we're saying that the fire immediately disabled the ability to communicate the fact that there WAS a fire to the pilots...

...but that seems unlikely too, because I imagine the 777 has backup systems that would alert pilots in case a system as critical as the fire detection equipment in the wheel assembly was not responding.

I'm not saying the fire scenario is impossible; I'm still erring on the side of this being a tragic systems failure, and not a malicious act. I just think it might be entirely unlike anything we've seen in the past.