After talking to a fighter pilot when he was a kid and despite being a wizard, he joined the Osean Air Defense Force and ended up in a copy of Heierlark Air Base completely filled up with wizards and Squibs. Then he proceeded to win a free-for-all deathmatch training fight after his graduation.
After being charged while still on his plane, Thunder 2 tried to escape, but was chased by Agent Sergio Turbo in another F-22. The Stu was ejected from his plane after a successful (and fast, due to Ace Combat game mechanics) lock-on, and plummeted to the ground after Sergio shredded his parachute using the on-board machine gun.
To add insult to the injury, aircrafts aren't supposed to automatically eject the pilots upon lock-on, even during training flights, but had to do this after the Stu stated so. Had he kept his mouth shut, he would have been a tougher challenge for the inexperienced agent.