Is there an airport near Kalamata with regular flights to Athens, or is it just as easy to go by bus into Athens and then get the train out to the airport.
Just don't take any photos while you're there. It's where the British plane spotting group got arrested and thrown into jail for taking pics of military planes. They protested their innocence, but must have fallen over any number of signs saying "don't take photos" in every language, apart from the fact that, as plane spotters, they'd be only too aware of when you can and when you can't!