Aircraft maneuvers to derive compensation coefficients to correct for the effects of the aircraft on magnetometer measurements. At high altitude the aircraft flies in different directions (heading test) and undergoes oscillating pitch, roll, and yaw of 5–10° to determine a figure of merit, which should be <1–2 nT. A new figure of merit has to be determined with each change of aircraft configuration. After proper compensation, the magnetic effects of the aircraft should cancel out regardless of the aircraft’s flight direction. See also lag test.