Heres the explanation I got when I got this photo from a friend:

"Too close for comfort I'd say...

This one was really close. Big post flight hose-down. Check out the speed brakes fully deployed on the F-16 on the left! Obviously the timing was off in this maneuver. The lead plane flies a constant airspeed, and the second plane adjusts his airspeed (relative motion) to stay as close possible without having a mid-air. In the photo, the second plane was going too fast and pulled his speed brakes and idled his engine (decreased contrail). He also was changing his altitude, based on the aeronautical law that states that two planes cannot occupy the same airspace at the same time. The altitude change was what saved his butt. I still can't believe they didn't swap paint. This is why people like air shows!!!!!!!!!!!!!!!!!!!!! "