Not sure if this feature exists already and I missed it but would it be possible to define speed changes in the flight plan? What I mean is fly one section of the FPL with cost index and then define a Mach Number in another section? At the airline I currently work for we plan with let’s say cost index 0 until NAT entry and thereafter we plan with a fixed Mach Number (let’s say .81 or .82) and once we make landfall we resume with cost index 0. At the moment Simbrief only lets us plan with either cost index or Mach number for the entire route. Would it be possible to add such a feature?
FWIW, I believe simBrief already plans oceanic segments at a constant MACH (but you don’t control it, it’s automatically selected based on your cost index). Also not all OFP formats indicate the oceanic speed clearly/specifically.