Short fantasy/sci-fi story in an anthology aimed at young readers in the late 70s/early 80s - I seem to remember reading it in late elementary school, though it could have been middle school. Story was about an Air Force pilot who lost a friend to a dragon in a storm cloud, but no one believed him, so he stole a plane and went back up to kill the dragon. He was catatonic and white-haired when the plane landed, and everyone thought he was just crazy, until they watched his gun-camera footage of his attack runs on the dragon.