Kill Cairne Achievement w/o being in TB [clarify?]

[chaose]

So I joined a raid group to kill the enemy faction leaders. Since my hearth was down and the group were already in the barrens, I had to make my sweet way across the world. That being said, when the raid group killed Cairne, I was still in the barrens. however, I got the achievement none the less.

However, from what other people said, for cities such as ogrimmar, you need to be in the room when thrall is killed to get the achievement. So I'm not sure if to get the Kill Cairne achievement w/o being in TB is for carine only or some kind of bug. If someone can confirm it would be great.

[Diabloss39]

I know when my group downed Cairne several people got it while not in the city, and I think the same was for Orgrimmar, as some people died and ran back.

[Meredy]

[NO QUESTIONS HERE]
this is no exploit and no bug

the achievments have been changed

[Facist]

You just have to be in the raid group to get the achievement.

[kickasskid54]

no i was in a raid group to kill darnassus queen and i was unable to make it in time so therfore couldnt get it. it might just be the case than you have to be in the same 'instance' as the target - Big instances include Azeroth Vanilla area, silvermoon area, darnassus area, exodar area, outlands and northrend