Peterson AFB is about 20 miles from the Academy. It's a popular stopping point for military aircraft (especially during football and skiing seasons). It isn't uncommon for Air Force planes to fly over the Academy during the week as planes approach and depart Peterson. Those Saturday football game flyovers are carefully coordinated and scheduled well in advance to reduce the risk of collisions. When you have a mix of helicopters, trainers, bombers, and fighters flying over the football stadium filled with thousands of fans, well, sightseer and lookie-loos aren't considered welcome. Even during the week, flyovers have to be coordinated with the Academy tower. On any given sunny day, the air over the Academy is filled with skydivers, gliders, and training planes. It's busy airspace.