In the recent threads it was often mentioned that IFR flights are started without a clearance on the ground and/or from uncontrolled airports. Being an IR noobie I don’t know about that possibility and how it is handled. I always thought one has to get an IFR clearance on the ground, either by an SID or a clearance in the type of "climb straight ahead, at 3000ft turn left heading 300, climb further, etc. and if this was not available the only other option was to file a Z flight plan.
Can someone elaborate on how such flights commence (or are even completely flown from point A to point B if not entering CAS)? How do you plan the routing and altitudes? Is there a difference between flying such a flight vs flying VFR if both are without a flight plan, except that if flying IFR the weather can be worse than VMC?
Automatically generate highly optimised IFR routes in the Eurocontrol system.