The Analog Interface Unit (AIU) is used in conjunction with the IS&S 9D-80130-1 Air Data Display Unit (ADDU), providing analog interface to the autopilot, navigation systems, and other using equipment. In application, air data is computed by ADDUs, then transmitted to a single AIU over isolated RS422 digital data links. The AIU converts the digital air data to the various analog formats and provides them to the aircraft systems. In the IS&S air data system, the ADDU is tasked with only the fundamental computation and display of air data. The AIU serves to remove the complexity and uncertainty of the accessory interface from the ADDU, thereby resulting in improved reliability and versatility of the flight deck instrument.