Looked intentional to me, OR the fighter pilot did not see the B-17 because its camo paint scheme blended with the ground, OR fighter pilot medical emergency due to be vaxxed.
Apparently the view from that particular fighter is very poor.
A pilot can’t see what is under their plane. No more than a semi driver can see what is behind their dry van trailer. When the much faster fighter plane was told to go ahead of the bomber, they both went into a “curve” and neither pilot saw the other plane. The fighter probably needed to fly that fast simply to avoid a stall/spin/crash?
As has been shown in many crashes, a cockpit pillar or other “partial obstruction” can cause a total blind spot as one aircraft overtakes another in a turn. The pilot may be temporarily blind-spotted while the co-pilot is looking down at other tasks.
If you don’t completely understand what “constant bearing, decreasing range” means, you should NOT be an airplane pilot. CBDR must be on your mind every single minute in the air!
At least in my realm, on the 2D ocean, I have minutes to find and correct a “blind spot” mistake before some ship runs me down. The same mistake in the air at 100s of knots closing speed....people will die.
Cessna vs passenger jet over San Diego.
Commuter plane sight-seeing the Queen Mary off France colliding with a Cessna another well-known and studied case.
https://en.wikipedia.org/wiki/Proteus_Airlines_Flight_706
Proteus Airlines Flight 706 was a scheduled commuter flight from Lyon, France to Lorient, France. On July 30, 1998, the Beechcraft 1900D operating the flight collided in mid-air with a Cessna 177 over Quiberon Bay. This accident was known as Quiberon Bay mid-air collision. Both aircraft crashed in the sea, killing fifteen people.
ALSO:
Brazilian Mid-Air Collision Case
An Embraer business jet and a Gol Airlines Boeing 737 commercial jetliner suffered a mid-air collision over the Brazilian jungle. The Traffic Collision Avoidance System (TCAS) on the Embraer was not operating.
https://www.kreindler.com/news/brazilian-mid-air-collision-case
My comment: The non-operability of collision avoidance tech, known or not known, does NOT get the pilot off the hook. You must ALWAYS be moving your head and eyes, scanning for CBDR contacts. And as much as possible, when he is in his seat, the copilot must share this responsibility to the maximum possible.
The P-63 driver was totally unconscious or deceased and simply flew into the the 17 from the left rear quadrant. Period.