Pilot

A Pilot is a generic terms for anyone operating a vehicles; however when most commanders referenced them they were referring to Pilots who survived destroyed US vehicles. US vehicles had titanium plated cock pits and flying US vehicles had their pilots equipped with parachutes giving them a good chance to survive. Having already been through a life or death experience they were deemed valuable asset. If they could be escorted to another vehicle they could show it's crew what they have learned on the battle field making the crew more efficient overall.

Counters
Being unarmed any attack would likely kill them. Quad Cannons and Gattling Tanks could easily chase down and slaughter Pilots before they had a chance of getting to another vehicle.