An enhanced vision and navigation system for guiding aircraft rescue and fire fighting vehicles at night and during certain low-visibility conditions. Note: The DEVS is comprised of three systems: (1) Navigation, which displays theARFF vehicle's position on a moving map display mounted in the cab; (2) Tracking, which provides two-way digital communication between the ARFF vehicle and the Emergency Command Center; and (3) Vision, which allows the ARFF vehicle operator to see in 0/0 visibility conditions. NFPA 414, 2001 ed