I found interesting site while I was looking for airport ringtones.
This site collecting various sound data file that can be distributed as creative commons. All data are posted by registered users. You can find many sound data files of an announce at airport, in a airplane, etc.
These are links for example.
You can preview sound by click on playing button which you can find at 'Waveform & Preview'. If you want download data, you have to register. Enjoy!