The detected heat flash could have been simply the engine explosion. In addition to a shockwave from a meteor/comet explosion, there is also the possibility of a plasma event. Remember the light flash from the nose of the plane hitting the WTC tower? A plane flying through a charged atmosphere becomes charged itself. If it then suddenly flies into a pocket of atmosphere with the opposite charge, it could discharge suddenly and produce basically it's own lightning. If that were to happen in combination with that oppositely charged air being sucked into a jet engine, I'm just speculating that it could trigger an explosion of the engine.