Sitan Test Results in the AFTI/F-16 Aircraft at Edwards Air Force Base

Drayton D. Boozer, J. Richard Fellerhoff

Abstract:	Sandia National Laboratories has developed a low-level attack aircraft terrain-aided navigation algorithm under reimbursably funded sponsorship of the Air Force Wright Aeronautical Laboratories, Avionics Laboratory (AFWAL/AAAN-2). The work has evolved from data collection in an instrumentation pod flown on an A7 aircraft in New Mexico, Tennessee, and Edwards Air Force Base (AFB), CA to realtime implementations and tests in a Twin Otter aircraft in New Mexico and Edwards, and most recently in the Advanced Fighter Technology Integration (AFTI) F-16 aircraft at Edwards. The AFTI/F-16 aircraft tests are the first real-time application of the Sandia Inertial TerrainAided Navigation (SITAN) approach to terrain-aided navigation on military aircraft. SIT AN was initially formulated at Sandia in the mid-1970s for possible use in a weapons-delivery system. The fundamental concept of SIT AN is the use of extended Kalman filter theory to provide essentially continuous terrain-aided navigation through the estimation of inertial navigation system errors from radar altimeter ground clearance measurements and on-board digital terrain elevation data (DTED). The particular implementation of SITAN in the AFTI/F-16, called AFTI/SITAN, has already been documented in the literature. The focus of this paper is the performance of AFTI/SITAN, as determined by Air Force tracking radar, during real-time testing in the AFTI/F-16 at Edwards AFB from September 1986 through April 1987. Terrain elevation was provided by photo-source, Defense Mapping Agency (DMA) Digital Land Mass System Level l DTED that had been compressed before flight and reconstructed in real-time by the Harris Corporation Digital Map Generator. The flight data support the conclusions that AFTI/SITAN reliably determines aircraft position within an initial 0.5 nm circular_ error probable (CEP) horizontal position error and tracks aircraft horizontal position with an accuracy of 75 m median radial error or CEP and vertical position to less than 13 m root-mean-square (RMS) error.
Published in:	Proceedings of the 1988 National Technical Meeting of The Institute of Navigation January 26 - 29, 1988 Santa Barbara, CA
Pages:	151 - 157
Cite this article:	Boozer, Drayton D., Fellerhoff, J. Richard, "Sitan Test Results in the AFTI/F-16 Aircraft at Edwards Air Force Base," Proceedings of the 1988 National Technical Meeting of The Institute of Navigation, Santa Barbara, CA, January 1988, pp. 151-157.
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