Very interesting. I guess I had supposed that most pilots on instrument approach would follow the prescribed approach cards, though I guess that Asiana flight really proves that isn't always the case, as well as inclement weather, etc.

You mention that most traffic has ADS-B out. Are you listening to non ADS-B Mode S transmissions, or any logging of Mode A/C transmissions? From a single monitoring point, I know that Mode A/C/S transmissions are far less interesting than ADS-B, however I was wonder where your "majority" claim came from. I suppose if you are near a commercial/passenger airport (as opposed to private/GA airport), this will probably be true.

I'd be happy to support your efforts if theres anything I can do (I come from an Embedded/Avionics background, including TCAS/Transponder development, as well as some data processing experience), though I can help more with Avionics theory than I can with statistics :). Feel free to send me a PM if you would like to discuss.

Best of luck to your efforts, it definitely seems like a cool project!