well, if it helps, pilots like Sara have probably been part of the Genesis project for a while, but weren't directly assigned to specific arks until a month or so ago- keeping some thousand good pilots sitting on standby for years at a time sounds like a waste of hours, where they could be pilotting supply shuttles to ferry supplies for building, or protecting supply lines like Sara was.

Edit: I did a thing! I also made several assumptions about the Ark's hangar and air-corps. No one else is really a part of the air-corp, other than perhaps Anderson- but he's a different sort of pilot, so I felt I could make some assumptions and world building.

Edit 2: the EVA harnesses I keep referring too is the bulky looking armor Sara is wearing in her picture, it is essentially a mini jetpack that lets pilots move while in vacuum, so they don't drift aimlessly away if they are out of their craft. It's armored enough to resist some small arms fire, but not to the degree of military armor, and it has enough air for about 6 hours of EVA. But chances are, if youre out there that long, there's a bigger problem at hand.