Technicaly, RAS is IAS corrected for Instrument and Pressure error. CAS is what an Air Data Computer will give you if fitted. The ADC corrects pitot pressure for Instrument, Pressure and any other error that the manufacturer thinks relevant.
So in essence, RAS and CAS are the same, but CAS only applies when an ADC is in the loop.
Yawn.
Last edited by Dan Winterland; 29th December 2002 at 19:25.