To aid aircrews in maintaining geographical orientation and to reduce navigation workload, an electronic chart display (ECD) system coupled with a Global Positioning System (GPS) was developed and ground-tested in the local area with both 1:500,000 and 1:100,000 scale digitized maps. System accuracy was not limited by GPS accuracy (+or-100 ft), but rather by the area represented by each map pixel. A calibration technique, which correlated reported GPS position with a known map location, made it possible to take full advantage of the increased system accuracy. This system was flight-tested during a NASA C-130 Ice and Snow Reflectance Study over Glacier National Park. The ECD system was compared to the paper map/inertial navigation system currently used for geographical orientation and navigation. Initial results show that GPS data were more accurate, but less reliable due to satellite constellation gaps. The navigator/ photographer assessed the ECD, even with its current limitations, to be as useful as the system with which he is highly experienced, but much more flexible.ETX