John Brannen may refer to: (wikipedia)
All we can say at this point is that there was not a catastrophic failure.
The destruction of the airplane certainly can hinder the investigation, but even with destruction as we've had with this airplane, there are clues in the wreckage that we can gather.
The video shows it in a near-vertical attitude when it impacted the ground. Obviously the thrust of the investigation is to try to figure out how it got into that attitude.
