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Helicopter copilot workload during nap-of-the-earth flight.

Two automatic navigation systems, a Doppler radar system and a projected map system, and a hand-held map were examined for their effects on copilot/navigator workload and performance. The automatic navigation systems reduced the number of navigation errors and the size of deviations from intended tract. The Doppler system reduced the time devoted to navigating and the number of verbal navigation messages exchanged between the pilot and copilot. The projected map system reduced visual workload. However, with all three navigation systems, more than 80% of the copilots' time was spent on navigation tasks, less than 10% of their time was visual "free time" that could be used for other tasks, and greater than 20% of the aircrew's time was occupied with navigation communications.