[bigtoona]

I think this was an incendiary device that was lit and stuck in the bathroom waste can next to the cockpit. I think burning wires would have given more warning. This had to be a low level explosion

[who_would_fardels_bear]

Another possibility is that the passengers were trying everything possible to break into the cockpit so they could fly the plane to where it was supposed to go.

Solving one problem (keeping terrorists out of the cockpit with stronger doors) leads to another problem (getting through the stronger door if the terrorist is already in the cockpit.)

[JohnBrowdie]

so the plane flew on for hours after an explosion and while it was more than likely on fire . . .