start-ups prior to EOBT
I'm in business aviation and fly within Europe and of course, sometimes our passengers turn up early and luckily ATC approves an early start-up (unless a slot applies of course), even if it is 30-40 minutes prior to the EOBT. I found the information that if start-up is requested prior to the EOBT mentioned in the flight plan, a new flight plan would have to be filed. However, until now, we never had to do that. I'm somehow surprised about that. How much flexibility is there for earlier than expected departures, are there any "unofficial" rules? Also, I read that a new flight plan has to be filed if the EOBT is exceeded by more than 11 minutes (if the FPL is subject to ATFM, which I suppose most flights are) or a "delay message" could be sent. How come ATC is flexible with early start-ups but not with late start-ups? Furthermore, I have never encountered the use of the "delay message" in real life so far. Is that still applied (my information source is my flight planning ATP folder dated 2002)?