This paper addresses itself to two basic questions which have been generated by the rapid increase in commercial aircraft complexity and in air traffic density now challenging the entire aviation industry. The on-board capability of general area navigation holds great promise for alleviating some of the difficulties brought about by each of these. In addition to being faced with the problem of how to quantify the advantages of this more flexible navigation capability, there is also a great concern with the question of how best to provide that capability in the cockpit.As a vehicle for examining these two related, but distinct subjects, a moving map display system, developed as a joint project by the Hughes Aircraft Company, United Air Lines, and Jeppesen Company, was installed in a Boeing 727 and operated for approximately 193 flight hours, primarily in the high traffic density environment between the Chicago and New York areas.As a result of the evaluation program, the advantages of navigation without the geographic restrictions of ground based radio aids were further substantiated. In addition, it was concluded by United flight crew personnel that the operational advantages of a pictorial display were sufficient to make the display an essential component in any area navigation system. Also recognized was the fact that this system can represent only a single step in what must be a large integrated program including all the participants in Air Traffic Control, both ground based and airborne.