Inflight Demonstrations of Curved Approaches and Missed Approaches in Mountainous Terrain

Keith W. Alter, Andrew K. Barrows, Per Enge, Chad W. Jennings, Bradford W. Parkinson, and J. David Powell

Abstract:	In addition to providing precise and robust 3-D position and velocity information, the Wide Area Augmentation System (WAAS) enables a new class of advanced flight displays that depict realtime "out-the-window"-type scenery even when the aircraft is flying through clouds. Accurate 3-D representation of terrain improves pilot spatial awareness and alerts pilots to the proximity of terrain. Additionally, desired flight path for approach and missed approach can be accurately displayed in the 3-D environment as a "pathway-in-the-sky," a series of hoops through which the pilot flies. Previous simulator and inflight studies have suggested that pilots can fly defined flight trajectories more precisely and with significantly less workload using the pathway-in-the-sky display rather than conventional flight instrumentation. More importantly, 3-D GPS positioning combined with the pathway display allows pilots to fly complex curved approaches and missed approaches that cannot necessarily be flown with current instrumentation. These curved terminal area trajectories could improve flight safety and flexibility through increased terrain separation, flight routing around noise-sensitive areas, lower minimums, etc. Perhaps the most exciting feature of the pathway-in-the- sky display is that it has the potential of being realized with relatively inexpensive LCD technology and attitude systems so as to be affordable to general aviation, business aviation, and regional air carriers. This paper focuses on inflight evaluations of the pathway-in- the-sky display conducted in southeast Alaska between Aug. 2 and Aug. 12, 1998, with experienced pilots flying a Beechcraft Queen Air piston twin. GPS position and velocity information for the display were provided by the Stanford WAAS prototype using data from the National Satellite Test Bed (NSTB). Out-the-window video was collected inflight to show how using the pathway symbology facilitates approaches to runways. Complex curved approaches, including approaches turning to a short (less than one mile) final, were flown under simulated instrument conditions. Finally, case demonstrations of curved missed approaches were flown from airports in mountainous terrain.
Published in:	Proceedings of the 11th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1998) September 15 - 18, 1998 Nashville, TN
Pages:	1165 - 1172
Cite this article:	Alter, Keith W., Barrows, Andrew K., Enge, Per, Jennings, Chad W., Parkinson, Bradford W., Powell, J. David, "Inflight Demonstrations of Curved Approaches and Missed Approaches in Mountainous Terrain," Proceedings of the 11th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1998), Nashville, TN, September 1998, pp. 1165-1172.
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