Originally Posted by
Pilot DAR
Yes, I agree, noting that this requirement is for a latest FAR Par 23 certified plane, but is not a requirement for a CAR 3 or older 23.1581. CAR 3.777 makes no mention of IAS/CAS. CAR 3.778(a) also makes no mention, though points you to 3.757, which refers to TAS (just add to the confusion, I suppose!). 23.1581 does not seem to mention IAS until revision 23-50 of 1996. So any plane certified prior to that would not have to comply.
PilotDAR is correct. When I rewrote the AFM for the Series 300 Twin Otter in 2012, I converted and published all the airspeeds in IAS. Because that aircraft was originally certified as a CAR 3 aircraft, AFM speeds had been given in CAS since original certification in the 1960s. So, in this particular case, it was a 'courtesy' (common sense is what I would call it) to publish the speeds in IAS - legally, I could have continued to use the original CAS speeds.