<title>Application of new GPS aircraft control/display system to topographic mapping of the Greenland ice cap</title>

Abstract

A facet of the NASA Greenland Ice Sheet mapping experiment is the requirement for precise navigation and positioning of the aircraft. In order to establish baseline elevational measurements it is necessary to reoccupy ifight tracks several times to ensure the validity of the survey. The Airborne Oceanographic Lidar1 (AOL) was operated in a scanning mode from an a!titude of 400 m so the survey swath width is '200m thus the real-time navigational requirement is +1-50 m to provide for at least a 50% swath overlap on repeated passes. We developed the GPS Flight Management System (GFMS) using the Global Positioning System (GPS). The GFMS inputs GPS position data to a PC which generates _ aircraft automatic pilot steering commands and a cockpit display including 1) course deviation indicators for cross-track error and altitude, 2) flight plan and waypoint map overlay oriented to the aircraft and 3) other mission pertinent numerical data.