Good question Rich. Reason is I was warned that one of the examiners up here gives an oral for the practical test 5 hrs. long. At my age, 70.... I can't afford to fail....
I've wondered as you suggest about using anything but IAS ....especially since CAS & IAS are identical per the POH for the RV12.
Maybe the only real concern would be TAS adjusted for varying altitude/temp ?
I've wondered about other calculations like isogonic lines with similar interest....what difference do isogonics make anyway? ...we live in Wisconsin, a virtual AGONIC location. Plus 1 or 2 around here means lpassing an airport on the left vs. right side of the plane!
Sure hope I pass this exam. Any suggestions welcome.
Tim