It seems every one here is using JComboBox as the From/To field. But I'm not going to follow it, I don't think it is an advisable pattern. Just consider following scenario: There are 10,000 flight records in db, but you have to search ALL those records to get (maybe just 20) distinct original/destination airports to fill in the ComboBox, in most cases, you fill in the JComboBox after just connected to the DB, during the long time(let's say) searching, the GUI will be dead there. To my point of view, JTextField is good enough, anyway, the airport code is very easy to be memorized! Does it make sense, anyone ?
I think the JComboBox is kind of inconvenient to use too. The user has to click the mouse two times and scroll down the vertical bar to select unless the desired option is of the top few. However, from the discussions among these forums, I found that canadidates whose use JComboBox usually get higher grade in the GUI section. That's a fact. Perhaps you need to document clearly and don't let the grader just think you only know to use the JTextField! :-)