Not all areas have Banshees that can be hijacked (such as the ones in Winter Contingency, where the Banshees don't have pilots). Good areas to achieve this are past the EMP barrier and before the spire in Tip of the Spear and within the caverns in The Package.
This achievement is glitched, in that one can get it by boarding a Falcon. First, betray allies such that they become hostile. Then go to an ally on a Falcon and board the Falcon. Boarding it will award the player the achievement. A good spot to perform this action is during Exodus, in the beginning of the final chapter, I Should Have Become A Watchmaker.