You miss the projectile, or maybe you hit it and just had no effect. Either way, the projectile gets closer and closer to you until it evades at the last second, instead colliding with the one chasing you. Their payloads combine and create a tremendous kaboom behind you that sets off all sorts of warnings on your HUD.
"Pilot, this is control, Sat-track is showing a massive explosion at your location. Are you still airborne?"