Originally Posted by
Pilot DAR
The design requirement states that Vso is defined in CAS
Yes I have seen that reg. Design airspeeds are CAS but operational airpseeds are IAS. The information has to be made available to the pilot in IAS as stated in the regulation 23.1581 that I quoted. Instrumentation during the flight test will determine the CAS, but the production airspeed system is also used in order to determine the IAS, which is what the pilot needs to know.
Therefore, if a pilot is factoring stall speed, the speed being factored should be the CAS speed, and the factor should also be CAS
Yes I agree. If you wish to factor the stalll speed the process is [CAS x factor] and then convert to IAS using the airspeed corrections table. No argument. The point I was responding to was:
stall speeds will be presented in calibrated airpseed, rather than indicated. Some flight manuals offer the courtesy of presenting it in both
...this is not a courtesy. The requirement for operational airpseeds in the AFM is 'indicated':
(c) The units used in the Airplane Flight Manual must be the same as those marked on the appropriate instruments and placards.
(d) All Airplane Flight Manual operational airspeeds, unless otherwise specified, must be presented as indicated airspeeds.