E6B Calculator + Airspeed Calculator
Airspeed Calculator
Select temperature as ISA deviation or OAT.
Select one speed below to calculate the remaining.
Theory / Formulas (ISA)
This calculator computes airspeed relationships using the International Standard Atmosphere (ISA) physical model. Altitude is first converted to meters and ISA temperature is obtained as \(T_{ISA} = T_0 - L\,h\), where \(T_0 = 288.15\,K\) and \(L = 0.0065\,K/m\). The user can define temperature either as ISA deviation \(\Delta ISA\) (in \(^\circ C\)) or as Outside Air Temperature (OAT, in \(^\circ C\)); internally both are converted to absolute temperature in Kelvin as \(T = T_{ISA} + \Delta ISA\) or \(T = OAT + 273.15\).
Static pressure is computed using the tropospheric ISA relation \(p = p_0\,\left(1 - \frac{L\,h}{T_0}\right)^{\frac{g}{R\,L}}\), and air density is then \(\rho = \frac{p}{R\,T}\).
Depending on the selected input speed, the remaining speeds are derived as follows: for Calibrated Airspeed (CAS), impact pressure is first computed as:
All calculations assume subsonic flow and standard compressible aerodynamics consistent with aviation performance practice.
Course, Ground Speed, & Wind Correction Angle
Inputs
Calculated