An Air force major, a B47 pilot, whom I knew very well, told me he saw a UFO silver shiny saucer in a vertical dive, buzz a B47 flying north in 1957 at low altitude, execute a 90 degree turn over the tail, fly from tail to over the canopy, and exit at 3000+ mph due north at 500 feet off the ground. He said the saucer was flying at a ~30 degree angle, not level, when it exited the area of view. He had binoculars on it all the way. He said it never slowed down from the dive.
He told me the saucer was about 30 feet wide and 4 feet thick in the middle and the thick middle part was not a smooth surface but rough, mottled. He was trained Air Force bomber pilot. He knew how to memorize details of any aircraft he saw.