FAA/Transport Canada GPS Ashtech Z-12 Test Results

Grant Youngdahl

Abstract:	The Federal Aviation Administration Technical Center and Transport Canada have been involved in precision and non-precision approach flight testing using the Global Positioning System (GPS). To measure an aircraft’s navigation system performance, a portable truth reference has been evaluated. This paper discusses the flight test evaluation of the Ashtech Z-12 duel-frequency receiver as a truth reference. The Z-12 utilizes Differential GPS through post processing to achieve the needed decimeter accuracy to evaluate precision approaches. Approaches were collected in a cooperative effort by both the FAA Tech Center and Transport Canada. Straight approaches starting at 4nm were flown into runway 13 at the Atlantic City international Airport on board an Aero Commander 68OE. Similar approaches were flown into runway 12 at Crows Landing aboard Transport Canada’s Challenger. Laser tracking provided a truth source for all flights. The flight tests consisted of over 70 approaches on which statistics were computed every tenth of a nautical mile along the flight path in terms of 2 Sigma, 95% errors. The data was evaluated in terms of cross-track sensor error, along-track sensor error, and vertical error. In addition, dynamic performances were tested by measuring its ability to continuously provide I Hz updates during aircraft maneuvers of the truth system. The purpose of this paper is to demonstrate the accuracy of the Ashtech Z-l 2 by providing a complete description of the flight tests including: airborne and ground equipment, post- processing procedures, and method of data reduction and analysis. Discussions will also entail the use of the Z-12 in present and future flight tests.
Published in:	Proceedings of the 1995 National Technical Meeting of The Institute of Navigation January 18 - 20, 1995 Disneyland Hotel Anaheim, CA
Pages:	381 - 385
Cite this article:	Youngdahl, Grant, "FAA/Transport Canada GPS Ashtech Z-12 Test Results," Proceedings of the 1995 National Technical Meeting of The Institute of Navigation, Anaheim, CA, January 1995, pp. 381-385.
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