Monitoring Sea Level Heights, Rise/Falling and Azimuth Angles of Flight of Aircrafts on the Basis of On-Board GPS Positioning and Geopotential Model EGM96, Principle of Crew Warning of Artificial and Natural Obstacles

Viliam Vatrt, Vlastimil Jonás

Abstract:	A methodology was developed for monitoring heights sea level (h.s.l.) H of aircrafts on the basis of geopotential value W0, geopotential model EGM96, and on-board GPS positioning. No geoid heights, no ellipsoidal heights are required in such a GPS/EGM96/W0 navigation. The geopotential W(M) values and the geoidal potential value W0 = (62 636 856.0 ± 0.50) m2·s-2 determined on the basis of TOPEX/POSEIDON altimeter data 1993-2000 make it possible to compute immediately the h.s.l. point of flight M. Exactly, W0 should be specified regarding Local Vertical Datum (LVD) used for determining H(M). The differences are small, however, if one meter accuracy is required, they should be taken into account. The accuracy of determining W(M) at point M depends on the errors in on-board GPS coordinates, as well as, on the distortions in EGM96. The last differ in different regions. The accuracy can be higher if GPS/leveling data are available over the given territory. In any case, the errors in EGM96 do not limit the accuracy of the solution. When topography is available then the height of flight above terrain can be monitored. Thus the developed technology can offer the same information as an on-board barometer. At landing manoeuvres, in general, the correction for the difference between the heights of the phase centre of the antenna and of the lower part of aircraft wheels should be applied. It should be specified by different types of aircrafts. During the landing manoeuvre the difference between the h.s.l. of lower part of aircrafts wheels and of the h.s.l. of Airport Point (ARP) is of special importance. The methodology developed might contribute to increasing the air traffic security. The location and h.s.l. of the natural, as well as artificial obstacles along the scheduled flight route should be known. Then, monitoring the h.s.l. of point M makes it possible the aircraft crew be warned if h.s.l. of M were smaller than h.s.l. of obstacles. The following manoeuvre can prevent a possible catastrophe. On the basis of the geocentric coordinates by on- board GPS receiver the rice/falling and azimuth angles of flight of aircraft/rocket can by monitored. The developed technology can offer the same information as an on-board compass and partly variometer. The developed methodologies can be applied globally, without any additional information. They are suitable for military purposes especially, because they have been developed as passive systems and they are very suitable when on-board apparatus troubles, orientation loss, airport technical landing equipments troubles, when landing manoeuvre is difficult, when bad weather conditions and/or other extraordinary affairs in running of flight. Methodologies developed are suitable for ground and marine navigation and landing manoeuvre at aircraft carrier too.
Published in:	Proceedings of the 15th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2002) September 24 - 27, 2002 Oregon Convention Center Portland, OR
Pages:	1047 - 1050
Cite this article:	Vatrt, Viliam, Jonás, Vlastimil, "Monitoring Sea Level Heights, Rise/Falling and Azimuth Angles of Flight of Aircrafts on the Basis of On-Board GPS Positioning and Geopotential Model EGM96, Principle of Crew Warning of Artificial and Natural Obstacles," Proceedings of the 15th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2002), Portland, OR, September 2002, pp. 1047-1050.
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