Abstract <p>The paper presents a method for in-flight calibration of a strapdown airborne gravimeter. it is assumed that the aircraft trajectory includes repeated flight lines and the gravity disturbance at each repeated line is the same. Therefore, it can be excluded as an unknown variable from the error equations of gravimeter’s inertial measurement unit by considering the differences between the measurements at two repeated lines. The remaining unknown values in the equations are the gravimeter’s inertial measurement unit instrumental errors (calibration parameters), which are considered constant during the flight. In the work, these parameters are estimated using the least squares method.</p>