Standard compass/attitude and heading reference system (C/AHRS) utilizing fiber optic gyroscopes

The requirement for replacement systems for in-service aircraft with aging compass and attitude heading reference systems was the basis for a joint U.S. Air Force/U.S. Navy program to develop, test, and acquire a standard low life-cycle-cost composite system. A single award was made to Smiths Industries in June 1991 to develop the C/AHRS, build fourteen prototypes, and support an extensive test program. The design approach chosen by Smiths included the use of fiber optic gyroscopes. In order to achieve the high reliability required for this replacement system, an Avionics Integrity Program (AVIP) has been implemented which includes extensive in-depth studies to determine actual environments which drive the design process. This paper presents a summary of the C/AHRS requirements and design approach