Equivalent airspeed

Equivalent Airspeed

Equivalent Airspeed (EAS) refers to the airspeed of an aircraft in standard atmosphere at sea level, which is equivalent to the Calibrated Airspeed (CAS). The EAS takes into account the effects of compressibility on the airspeed of the aircraft as it moves through the air.

As an aircraft’s airspeed and altitude increase, the air pressure surrounding the craft reduces, causing a decrease in air density. This decrease in air density, in turn, causes the air to act in a compressible manner around the aircraft’s surfaces. The compressibility effect on the airspeed causes the CAS to be higher than it should be. Hence the EAS is a measure of the airspeed that corrects for the compressibility effect on the CAS at a given altitude and temperature.

Aircraft pilots rely on the EAS for accurate airspeed control, which is essential in ensuring safe operations and optimal performance. EAS is an essential parameter in flight manuals for aircraft, and it is used in the design and development of aerospace vehicles.