As an expansion, this doesn't have the sheer page count that the core book does, but it's really efficient. With three pages for altitude, temperature and extreme conditions, it builds a new environment to fly in that can be challenging to brave on its own, four pages for mountain terrain build a new type of land to fear and respect in equal measure and add a bit to regular ground combat, and so on. It punches above its weight, fitting tantalizing snippets of lore in new enemies and a whole variety of new challenges and adventures to take part in.

One thing I would appreciate is a few more planes that are well suited to the high altitudes, or worked out examples of existing planes modified. I'm fine living in the plane builder, but I know other players might prefer not to get into it or play with planes they know have gotten balancing attention.