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GPS APPLICATIONS AND REQUIREMENTS 31 Operational Procedures Currently GPS is being approved by the FAA to operate under the same procedures used for existing navigation aids. If GPS is to provide more efficiency to present operations, however, there have to be accompanying changes in technical infrastructure and institutional culture. The major benefits of GPS navigation and surveillance will only be achieved when its coverage and accuracy are exploited to enable aircraft to fly user- preferred flight paths with minimal command and control from air traffic controllers. The benefits and enabling factors for these new operational procedures are discussed below.23 Most instrument flights are constrained to specified paths that facilitate the air traffic management (ATM) system's human-controlled separation of aircraft. Since GPS-equipped aircraft will be able to fly any desired flight path with high accuracy, users (especially air carriers) can potentially gain significant fuel and time efficiencies by having the ability to fly the most advantageous routing from one destination to another while independently amending their flight path as necessary to avoid congestion and potential conflicts with other aircraft. In order to make this change in procedure possible, as a minimum, the following enabling factors will have to be in place: ⢠automation that can cope with numerous aircraft flight path crossings, unlike the present essentially linear flow of traffic; ⢠a changed ATM culture that accepts a high level of automation for conflict prediction and resolution, and allows more autonomy in the cockpit for route selection and aircraft separation; ⢠highly reliable flight management systems aboard all aircraft to ensure that the same airport and route information is available to each aircraft flying in the national airspace system; ⢠two-way data links that provide an interface between ATM and aircraft flight management systems for such purposes as automatic negotiation of flight clearances (with pilot approval) and updates to airport and air route databases; and, ⢠cockpit display of traffic information to allow all aircraft to provide self-separation and enhanced collision avoidance. 23 More information on this concept, known as ''free flight", can be found in the following document: RTCA, Inc., Report of the RTCA Board of Directors' Select Committee on Free Flight (Washington, D.C., 18 January 1995).
