From publisher blurb:
In this product you will find details on the Ace profession tree. An Ace is someone with an exceptional ability to push a vehicle (and himself) beyond its normal boundaries, squeezing nigh-preternatural performance out of their machines. They can endeavor to attain new heights of speed, keep their vehicle together when it should be shaking apart, and force it to achieve feats of daring that should be impossible.
In order to allow for character specialization, many Edges of the Ace profession tree have been broken down into three variations on the same effect, separating the mechanics between aircraft, ground vehicles, and watercraft. However, by all means combine the Edges into a single version of the end result if you think a more generalized approach better suits your game.