[′in·tə‚grād·əd in′ər·shəl ‚nav·ə′gā·shən ‚sis·təm] (navigation) An air navigation system in which an inertial navigation or inertial reference subsystem is interconnected with all the other subsystems associated with avionics, so that data from all subsystems are automatically blended and interpreted to provide the control data needed to operate aircraft efficiently and safely.AcronymsSeeIINS