ALG is a combination of raster imaging sensor, head-up displays, flight guidance and procedures which allow pilots to perform hand flown aircraft maneuvers in adverse weather, at night, or in low visibility conditions at facilities with minimal or no ground aids. Maneuvers in the context of ALG relate to takeoff, landing, rollout, taxi and terminal parking. Commercial needs are driven by potential revenue savings since today only 43 Type III and 80 Type II instrumented landing system (ILS) runway ends in the United States are equipped for lower minimum flight operations. Additionally, most of these ILS facilities are clustered at major gateway airports which further impacts on dispatch authority and general ATC regional delays. Infrastructure consists to upgrade additional runways must not only account for the high integrity ground instrumentation, but also the installation of lights and markers mandated for Cat III operations. The military services ability to train under realistic battlefield conditions, to project power globally in support of national interests, while providing humanitarian aid, is significantly impaired by the inability to conduct precision approaches and landings in low visibility conditions to either instrumented runways or to a more tactical environment with operations into and out of unprepared landing strips, particularly when time does not permit deployment of ground aids and the verification of their integrity. Recently, Lear Astronics, in cooperation with Consortium members of the ALG Program, concluded a flight test program which evaluated the utility of the ALG system in meeting both civil and military needs. Those results are the subject of this paper.
The ever increasing demand in the airline industry to reduce the costs associated with weather- related flight delays and cancellations has resulted in the need to be able to land an aircraft in low visibility. This has influenced research in recent years in the development of enhanced vision systems which allow all-weather operations, by providing both visual cues to the pilot and an independent integrity monitor. This research has focused on providing aircraft users with both enhanced performance and a cost effective landing solution with less dependence on ground systems, and has interested both the military and civil aircraft operator communities. The Autonomous Landing Guidance (ALG) system provides the capability to land in low visibility by displaying to the pilot an image of the real world without the need for an onboard Category II or III (CAT II/III) autoload system and without the associated ground facilities normally required. Besides the inherent advantage of saving the cost of expensive installations at airports, ALG also has the effect of inevitably solving the airport capacity problem, weather-related delays and diversions, and airport closures. Low visibility conditions typically cause the complete shutdown of smaller regional airports and reduces the availability of runways at major hubs, which creates a capacity problem to airlines.