Not sure if I'm getting the wording right, but considering no major upgrades are done, what do you think the average age, in years, is of an airport before it gets (or should get) a major make over?
I ask this because I always feel most US airports are in dire need of one. It seems that a lot of the major US airports were built (or had major upgrades) in the 70s and early 80s. Save for a few (SFO, ORD, JFK T4/9, DCA), most US airports seem to be stuck in the past. Poorly lit, cramped, etc.