This paper describes the design and performance analysis of HTS(Helmet pose Tracking System), providing coincident LOS(Line of Sight) between aircraft and HMD(Helmet Mounted Display) which displays flight and mission information on Pilot helmet. The functionality and performance of the HMD system depends on the performance of HTS (Helmet Tracking System). The goal of HTS system design is to meet real-time performance by synchronizing the latency of non-periodic sensory systems and high accurate tracking performance. To prove the performance of the proposed approach using ACF (Adaptive Complementary Filter), a robust hybrid pose tracking scheme with a fusion of optical sensor and inertial sensor, it took an experiment through an implemented test-bed. The experimental results show accurate and reliable tracking performance despite external errors.