I know how to enter the flight plan per se. It’s simple enough in any of the Garmins.
This is typically fine when I’m flying the TBM or Longitude. The issue I have is when I’m using a small GA aircraft, ATC will then tell me to climb to something stupid like FL390 when I’m in a C172. Of course, there’s no way to tell ATC this. I can’t even request a lower altitude from them, as they’ll deny it because I haven’t climbed to the altitude they assigned to me first. And eventually they’ll cancel my IFR because I can’t comply with their direction. Of course, if I re-file in flight, it’s the same story all over again.
Is there something I’m missing here or am I stuck just entering my flight plan from the world map?