i4dnf - Those look like interesting options to make the radio comms sounds more realistic - I'll need to take a look!
durk - I've had a look in more detail at what we have already. At present we use festival externally to put together all the words used in ATIS (including airport names) individually into an indexed .wav file that's checked into (IIRC) fgdata. With a limited AI/ATC vocabulary we might be able to do the same for the AI comms.
-Stuart