I got this on "Tip of the Spear" at Mission point Charlie (least I hope it's Charlie as I've been playing the Campaign straight through on Legendary on a solo run), where you've just crashed and have to make it to the spire to blow it up.
First, grab a jet pack (and some health if you wish), just in case.
Second, kill the enemies as you go; i prefer sniping them with the DMR. Grab a Plasma Pistol off of a Grunt, and swap the DMR for a Needler Rifle when your ammo gets low.
Third, after you get close enough to the Spire (after killing an Elite manning a Plasma Turret) one or two Banshees will dive at you while firing their weapons on you. Avoid the shots and hit the Banshee with a charged-up up Plasma Pistol shot to disable it and make it crash (make sure you're NOT in its path when it does); rush up and hold
(or whichever button you've set the Action Command for) to hijack the Banshee. After a few seconds of flying it, the achievement will pop.
Side note: If you want to hold off on getting this achievement, I suggest doing it in the chapter "New Alexandira" and following x1001x Puppys's guide for