Most NCAAs and/or ANSPs have published reminders over the past few years about the supposed importance of ensuring that the Flight ID transmitted via Mode S matches the flight plan identification.
Does anyone know of any sanctions that have been applied to crews who chooses to deliberately abuse the system ?
Here's a good example of what I mean, courtesy of our Canadian brethren (don't click on the link if you're easily offended):
www.civilaircraftregisters.org/Mode_S_Resources/C-GKFB%20Callsign.gif