In der Luftfahrt unterscheidet man verschiedene Fluggeschwindigkeiten:
Calibrated airspeed (CAS) is indicated airspeed corrected for instrument errors, position error (due to incorrect pressure at the static port) and installation errors.
Calibrated airspeed values less than the speed of sound at standard sea level (661.4788 knots) are calculated as follows:
Units other than Knots and inches of mercury can be used, if used consistently.
This expression is based on the form of Bernoulli's equation applicable to a perfect, compressible gas. The values for Po and Ao are consistent with the ISA i.e. the conditions under which airspeed indicators are calibrated.