I wonder if this plane was converted to one of those new fangled lithium battery packs that tend to overheat and catch fire on the trip 7.
https://en.wikipedia.org/wiki/Boeing_787_Dreamliner_battery_problems
Or someone’s iPad or iPhone or other personal electronic device using said battery-type.
The plane was sent going to Egypt filled with a bunch of people from the region. Even if the plan was transporting a bunch of highly unstable explosives in a bumpy wind-storm, my bet would still be on terrorism.