Gulf War I, being in the desert under clear blue skies, I could see from my position Iraqi forces massing in the distance. . .well over 5 miles away. Could see individual movement.
You eye catches movement and while he likely could not “see” the individual person, he did see movement (dropping) of the bodies as they jumped.
Seems to me that a body falling from that height, with the tremendous velocity would be detectable from miles away.