“Many were in the 1940s-1950s period and were in the general area near military bases where advanced radar and microwave technology was under development.”
My theory is the UFO crash was the cover story. Remember we snuck von Braun and the other Nazi rocket scientists in through Mexico. We were testing V-2 rockets at White Sands. Maybe it was a V-2 that crashed. Imagine the outrage at that time if it was learned we let those Nazis into the country like that. People were still cheesed off at the Germans then. Our Germans only became the good guys because of the Cold War.
“My theory is the UFO crash was the cover story.”
The problem with that is that the crashes were all hidden from the public except for the brief newspaper story in Roswell in 1947.
Read the manual—these are standard metrics followed by governments all over the world:
https://cdn.preterhuman.net/texts/wars_and_weapons/Majestic_12-UFO_Official_Manual.pdf