Even at 20 years amortization a builder might be able to do okay in some markets >if< these hangars could be built in a cost-effective way. But in most cases they can't. The airport (FAA? State aviation authority?) will require 8000 PSI concrete 10" thick and a rebar schedule sufficient to support a Saturn V, every scrap of labor will be union and the contractors approved by the county (cha-Ching!), the plans and work will need to be inspected at every step by the county engineer (who probably has zero experience in building airport structures, so he'll need to get a nod from a hired consultant, etc). I wonder if it would be easier to get a "through the gate" setup with the airport: Buy a few acres abutting the airport, build a good gate with the same type of access control used by the airport, and build the hangars on private land. It would still be a >giant< headache, but once the trail had been blazed and there was a standard package to use, and some (undetermined method I can't imagine) way to show the airport managers and authorities that doing this is good for them, then maybe it would work. But I believe the trend on these "through the fence" agreements was turning the other way, at least as-of a few years ago.