first tgt lead?

How do I kill this guy. I've closed in,with dfm and shot him for like ten minutes. Huge chunks of wing fly off, and I've hit him with sustained gunfire ten seconds,straight on more than one occasion, but no matter how much I hit him he just won't die. I'm pretty sure I've landed some close range missile strikes, too.

I feel silly asking, but have I missed something?

Haha, nevermind. It was a bug. I loaded the checkpoint and tried it again and took him down immediately. I think the game messed up when it tried to load the second piece the tutorial, and he has infinite health until the game shows you that message about close range missile locks.