Definition
Calibrated airspeed (CAS) is the indicated airspeed of an aircraft corrected for installation error and instrument error. CAS is equal to true airspeed in standard atmospheric conditions at sea level. It is the airspeed value used when referencing aircraft performance and operating limitations such as VS, VFE, VNO, and VNE.
Plain English
It is the airspeed shown on the cockpit gauge after small built-in errors have been corrected. It is the speed value the manufacturer uses when listing the speeds you must respect, like stall speed and never-exceed speed.
Context Anchor
Seen in aircraft limitations, performance information, and light-sport aircraft rules, where required speeds may be stated in knots CAS.
Derivation
Calibrated comes from the Latin calibrare, meaning to measure or adjust to a known standard. Here it signals that the raw indicated airspeed has been adjusted to remove known measurement errors, giving a more trustworthy figure.
Why Pilots Care
Using CAS gives accurate performance numbers for takeoff, climb, and landing distances.
Intuition Check
CAS is not simply “the airspeed shown on the gauge.” It is that airspeed after known errors have been corrected.
Example Sentence 1
The POH listed the flap extension speed in CAS, so the pilot checked the airspeed correction chart before slowing for the approach.
Example Sentence 2
Light-sport aircraft performance tables list speeds in CAS to ensure consistent results across different installations.