The necessity of prescribed burning large units over short periods of time prompted fire managers at Yosemite National Park to experiment with a helicopter-mounted fusee dropper. A 4,800 acre unit was ignited with the device in October of 1979. Although the fusee dropper successfully ignited fires on steep slopes with dense canopies, the resulting burn pattern was unsatisfactory. Long, eliptically-shaped fires burned upslope with little or no downhill or lateral movement.