During the spot landing stage, the flight control system requires real-time and high precision relative location information, especially the height information. However, INS/ GPS integrated navigation with the sonar altimeter can hardly meet the requirements. 在SUH的定点降落中,飞控系统需要实时且高精度的相对位置信息,特别是离地高度信息,而传统INS/GPS组合导航配合声纳高度计并不能满足要求。