Published on August 11, 2009 easy to do on map vahalla
or there are two places in campain you can do it
1st is on the part right after you take out the first wraith on the mission covenant simply save som lazer ammmo and lazer one of the banshees
or on the storm mission durring the scarab battle use the mounted missle pods and wait for a banshe to come close and lock on and destroy it