The following are the major functions of a flight management system (Honeywell, 1989):

  1. Flight planning.

  2. Navigational computation of a plane's position.

  3. Guidance commands for the autopilot and flight director, in conjunction with integrated thrust management and autothrottle control, to fly optimal vertical profiles while also flying the lateral path.

  4. Navigation display data to generate a horizontal situation indicator map display and features.

  5. Navigation radio tuning.

  6. Storage of database for navigation, aerodynamic, and engine data.

  7. Interface to inertial reference system (IRS).

  8. Performance optimization.

  9. Thrust calculation.

  10. Autothrottle control.

  11. Polar navigation/operation capability.

  12. Simulator capability to allow for simulator training and flight operations.

The relevance of the flight management system to air traffic control is threefold. First, as we reviewed in the Phase I report, many of the human factors lessons learned in automation of the flight management system are directly relevant to air traffic control automation. Second, the flight management system provides the aircraft with opportunities to fly extremely efficient user-preferred routes, a source of frustration to the airlines that must often remain on air traffic control-preferred airways. Third, given that the aircraft flight plans are encoded digitally, when linked digitally to the ground by data link, there is the capability to send information downward to air traffic control regarding intent and upward regarding flight control, as well as to share information between aircraft. This enhanced data sharing has profound implications for the future automation of the national airspace system.


In the late 1970s, microprocessor technology had developed to the point at which not only were the electronic devices becoming more and more sophisticated, but also the individual devices could be linked to form a flight management system, rather than a collection of independent, albeit sophisticated, boxes (Billings, 1996b). The individual devices architecture was exemplified by the wide-body aircraft of the period: B-747, L-1011, and DC-10. In these planes, inertial and radio (e.g., Loran and Omega) navigation not only located the plane on the earth's surface, but could also provide guidance commands to the autopilot

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