# Equivalent airspeed (in function of Mach number)

## Description

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.

It can be calculated as a function of Mach number.

Related formulas## Variables

EAS | equivalent airspeed (m/s) |

a_{0} | standard speed of sound at 15 °C (661.47 knots) (m/s) |

M | aircraft Mach number (dimensionless) |

P | static pressure (Pa) |

P_{0} | standard sea level pressure (1013.25 hPa) (Pa) |