Me and SEE did this together in identical realistic training games last night while in a party chat. We were trying to get him the achievment. It was rather...frustrating shall we say. All the stunts you need to do are the ones from the encyclopedia, these are barrel roll (really an aileron roll), split S, Imellman, loop, hide in the clouds, spin recovery. All but the spin give you a acnolagement sign pop up if done correctly, so leave the spin till last so you will know if its sucessfull if you get the trophy/achievement.

Now for some reason that we couldn't fathom. I was getting the split S and immelman pop ups allmost every the time even with rather messy attempts ,but now and then after a good clean immelman or split S I would get no pop up. Evangelous on the other hand was doing perfect split S's and Immelmans and not getting any pop ups at all. He did manage to get an immelman in one game but then couldn't get a split S before the game timer ran down. Next he did an unlimited time training, switched his view to real cockpit and did a good few split S's straight away while doing nothing else different than before. For a while we thought we had sussed the problem that some people were having, but then for about half an hour this thime He just could not get the immelman to pop up when in the game before he got it multiple times no problem. He talked me though what he was doing and it was pretty clear he was doing nothing wrong. It was very stange. All this time there was me flying in the same plane same weather, using every different view and still getting it almost every time. Finaly after countless attempts and with SEE about to give up, "immelman" did pop up and he unlocked the achievement. Pheeww.

The only thing we were doing different ly was I was using a pad and he was using a stick. So if you are still unable to get this stunt unlock and are using a stick, try it using the joypad instead and see if that makes a difference.

I use a dualshock 3 wireless for PS3. Its a little busted up, because if you press down hard enough of left stick the up button on the pad triggers.

What I did was fly a Spitfire IX, full sensitivity, 60% power, and just gently pulled back on the stick.