IMC in open FIR - classification?
Scenario:
You take off from airfield A, in uncontrolled airspace, set course for airfield B, also in uncontrolled airspace.
Climb to say 2800ft on reg QNH. Being IMC rated, you plan to enter IMC. This infers that you are clearly no longer VFR, so conforming to IFR, albeit below FL030 on QNH. You decide to call for a RAS service.
My question is, when identifying yourself to the ATSU, you state that you are IFR, 2800ft requesting RAS, giving all other relevant details. Does this constitue an IFR flight plan as filed over RT, thereby enabling the ATSU to issue you with a radar service (RAS)? I am trying to clarify the rules in my head here. As I understand it, if you are IFR, the only time you need to pre-file a flight plan is if you will be IFR in controlled airspace (not class A if you have an IMC rating only) or can this also be passed over RT?
When cancelling IFR in uncontrolled, I also believe that the words "Request cancel IFR" have to be initiated by the pilot before the ATSU can downgrade to an FIS or RIS?
Any help much appreciated.