It wasnt a single engine plane. His uncle was a passenger, not a pilot. It wasnt shot down, it developed engine trouble, a mechanical failure. The pilot tried to attempt a crash landing in the water. Only one man, the engineer, survived (picked out of the water by a barge).
https://pows.jiaponline.org/2021/05/remembering-president-bidens-uncle.html
https://pacificwrecks.com/aircraft/a-20/42-86768.html
The plane wreckage was never found though recently its believed the location of the wreckage has been discovered.
well- he was close LOL