1. When above the transition altitude and IFR, unless otherwise directed by ATC, or unable to comply because of a TMA being in the way,
2. IFR is either a state of mind and terrain, or a state of weather. If you are IMC then you are IFR, if you are VMC then you may be either VFR or IFR, but if IFR you should also be above the MSA.
3. If you are receiving a service you should inform the service provider of the flight rules under which you are operating.
4. OCAS you can change the rules as often and whenever you like to comply with 2. In CAS you will have been given a clearance and so must comply with that clearance or request a change.
Last edited by Fuji Abound; 29th June 2010 at 16:01.