The C-17 dual-channel air data computer

The C-17 Air Data Computer (ADC) has been developed by Honeywell Inc., Defense Avionics Systems Division, Albuquerque, New Mexico, under subcontract to McDonnell Douglas Aircraft, Long Beach, California, for use as the primary air data system on the U.S. Air Force C-17A military air transport. Each C-17 ADC Line Replaceable Unit (LRU) provides the equivalent function of two independent ADC channels. A single channel in the ADC features a self contained 1750 SEAFAC certified processor capable of providing air data related flight information via two MIL-STD-1553B remote terminals. There are two ADCs per aircraft shipset, thus providing an equivalent of four independent ADC channels per airplane. The secondary source of input data to the ADC is the 1553B bus. This interface supplies the ADC with unique flight characteristic data which is utilized by the ADC processor to correct altitude and airspeed data for pressure source errors