Equivalent airspeed

Equivalent airspeed (EAS) is the airspeed at sea level in the International Standard Atmosphere at which the dynamic pressure is the same as the dynamic pressure at the true airspeed (TAS) and altitude at which the aircraft is flying. In low-speed flight, it is the speed which would be shown by an airspeed indicator with zero error. It is useful for predicting aircraft handling, aerodynamic loads, stalling etc.

${\displaystyle EAS=TAS\times {\sqrt {\frac {\rho }{\rho _{0}}}}}$

where:

${\displaystyle \rho \,}$ is actual air density.

${\displaystyle \rho _{0}\,}$ is standard sea level density (1.225 kg/m³ or 0.00237 slug/ft³).

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