Hi,
well as far as I know the maps API will find the closes address to the given location. I guess you would have to do a 2-phase seach.
1. Get the nearest address to the current location (
http://code.google.com/intl/de-DE/apis/maps/documentation/javascript/v2/services.html#ReverseGeocoding)
2. use google maps to search for "{zip} airport" and in my case I allways found the airport.