Using the INS position and velocity error as the state variables, and the residual error as the observation which is
constructed from the observation sequence and pseudo observation sequence computed with the INS data and the altimeter
information, an iterative algorithm is proposed. The process of the iterative algorithm includes reducing the influence of noise
by means of mean denoising approach, estimating the INS position error and velocity error simultaneously, and updating the
observation equation. Simulation results show the effectiveness of the proposed method.