Let’s say it was a FOD incident. What would have a one-second-prior-to-impact window gained the P-63? You also mention a pitch-down moment - let’s say that happened and was the cause of the collision. Back up that one second and remove the supposed FOD and pitch-down chain: by how much would the P-63 have cleared the B-17? A few feet? Would it still have been belly-up to the B-17? Would it have had to perform an evasive maneuver in that one second to safely clear the B-17? Would that maneuver have been part of the plan? I don’t think giving back that one second buys enough time to not make this a safety issue. The separation bubble was still violated and it doesn’t answer the sightline problem. If this was truly the case, it was still questionable planning and a hell of a lot of bad luck.