Nearest near-miss?

I was "shot down" by a B-17! The B-17 was operating from ALB, about 20 miles away from our gliding home plate, Saratoga County Airport, NY (5B2). The B-17 was taking well heeled passengers, who were willing to shell out several hundred bucks, for a ride. I was recently licensed in gliders and was struggling in a weak thermal near 5B2 at 2200'. The B-17 came on the CTAF and and announced he was doing a pass over 5B2 at 2000'. Before I could respond on the radio, someone else replied and told the B-17 "gliders in the area". The B-17 replied "glider in sight, no factor". I thought I was safe, but apparently the B-17 had another glider in sight and passed directly below me. The roar of those four big radials was deafening, and I remember looking right into the eyes of the passenger riding in the top turret. The close encounter had me so shook that I lost my thermal and ended up having to land soon thereafter - thus the "shoot down". I now have a transponder in my newer glider.

Cruising down the ridge in central Pa. late afternoon in the fall and looking into the lowering sun. It wasn't blinding yet but still a factor. Suddenly, there was a another glider coming at me head-on and quite near my altitude. I instinctively buried the stick. There was no thinking involved. He passed over me with maybe 50'(or less) separating us vertically. There was no lateral separation. Had we been at the same altitude our wings would have hit, maybe even striking each other fuselages. I don't know who it was and no one reported anything like this once all were back on the ground. Either he never saw me or maybe was flying from another field. It scared the crap out of me. That we didn't collide was simply a matter of luck.

1981, during PPL training (I already had a GPL) at a military base in Canada that also did commercial and GA traffic.

ATC had given me clearance to land and I was about 50' above the tarmac in a C-152 when ATC called and said, "You are being overtaken by a Douglas 9, many knots". Looked out the back window to see that I was about to become a hood ornament. Instructor took over, firewalled the throttle and shifted to the side of the runway while trying to climb away. The DC-9 passed us about 10 seconds later on his rollout.