there are certain nouns--I think generally indicating common places--where the definite article is omitted in Italian. I used to work with an Italian guy that could not stand Marianne Esposito's cooking show "Ciao, Italia!", because at the beginning of every show, she would say "Let's go nella cucina...". He said it hurt his ears when she said that, because it's supposed to be "in cucina".
How about these translations: in aeroporto = in the airport; presso or all'aeroporto =at the airport
This seems to be one of the only times when English has an article and Italian doesn't.