Capt. Eddie Gordon (William O'Leary) who's Callsign is Black Angel has become fanatically convinced he must nuke Las Vegas in order to cleanse it of sin thereby pleasing the man upstairs. He has rigged it in such away that should he be shot down the device shall detonate.
Col. Matt Ryan, Callsign Ringleader (Peter Strauss), clearly knowing he'll set off said bomb and get caught in the resulting blast wave goads Gordon and his ego prompting him to break off his bombing run to engage Ryan in a dogfight over the skies of the surrounding desert, leading Gordon further and further away from any populated areas. Once both are now out in the middle of nowhere, Ryan manages to lock on to Gordon's bomb and detonate it, vaporizing them both.
The pentagon swiftly covers up this incident, with both pilots just being tragic victims of a tragic nuclear accident.
Thanks ND Woods!