Kerry county airport (also called Farranfore) is situated a a dozen or so miles away, roughly halfway to Killarney. It might be one of the world's most scenic places to land, but the range of flights is very limited. Presently Aer Arann will get you to Dublin (Ryanair gave up on that one) whilst Ryanair connect to Stansted (UK), Hahn (Germany), as well as some flights for Spain and Portugal. Cork and Shannon are both within reasonable driving distances (less than 2 hours).
Regular buses connect Tralee to the terminal.
Kerry international airport is about 40-60 mins away from Tralee in a little place called Farranfore. It mainly has flights to Dublin and London.
Otherwise you can fly to Shannon Airport and drive via Limerick to get to Tralee