The paper offers a solution of the problem related to calibration of heading displacement in scale bases of  Strapdown Inertial Navigation Systems (SINS) with application of low accuracy gyroscopes (fiber-optic, micromechanical) and multi-antenna  reception equipment of satellite navigation systems (SNS), which are capable to generate parameters of orientation (in addition to position and speed). The difficulty in solving this problem consists in the necessity to separate SINS heading displacements (a) and  SNS (dKs) involved in heading measurements. In the proposed original method this problem is avoided, since the a error is estimated without use of heading measurements. Conditions for observability of a  without use of heading measurements, the time of its estimation  using the Kalman filter in the feedback, and also simulation results confirming the analytical calculations are obtained.