Here we use postcodes

But usairways.com, when finding the closest airport, asks you for either a city or a military base.

This makes more sense when it asks you whether your military base (or, possibly, city) is in the US or Canada. I imagine they're appealing to Army types who are based in a country they can't spell.

As it happens, usairways.com is one of those dread airline sites that decides that the back button must die, and therefore refuses to countenance its existence. So I boycotted it, and found Airtran, which appears to be the low-budget airline I was looking for, and who I saw mentioned on an airline tariff aggregator a while ago, but ignored because the price was in fact artificially inflated (don't know if this is the fault of the aggregator site for being wrong, or for airtran for not wanting to give traffic to a competitor)

If I wasn't acutely aware that the airline industry must be full of shysters and bogus 30-year-old technology, and is already too full of websites, I'd be tempted to barge in and try and sort it out. That, and the fact that I don't have the money to set up a company...