APU-related fuel explosion as source of IR heat event?
I find this fuel explosion hypothesis a credible possibility purely by elimination, so technically informed readers may be able to contradict it definitively. The absence of plausible acknowledgement by Daesh /Al Q'aeda and the apparent irrelevance of missile involvement moves the focus to the heat flash as the most plausible published evidence of a bomb. The UK seem to have plumped for the bomb theory on a safety-first basis, and have pretty well admitted that the overall case is not overwhelming.