If there is a second surface below this surface (e.g. top of base, inside base), you can recover the player and try again if they get knocked out of the map.
Pillars, portals, and other objects can make great surfaces.
Get in a Banshee and reverse until you are just above the player. You'll have to know this indirectly, without looking at them.
Drop your banshee on top of the player. You need to squeeze the player into the middle part of the tail portion of the Banshee. The Banshee should be angled so the tail of the Banshee is just about parallel with the ground.
Hold reverse to fly with the player inside of your Banshee. Aim down to ascend into the sky, avoiding objects near the ground.