Prior to the September 4, 2017 flight, the glider absolute world altitude record stood at 15,460 meters (50,727 feet), which is the altitude reached by Steve Fossett and Einar Enevoldson during Perlan Mission I. The previous record was 14,938 meters (49,009 feet). It was set in 1986 by Robert R. Harris, flying from California City and reaching his record height over Mount Whitney, California. This may be near the limit for standing mountain waves in temperate latitudes, although in unusual meteorological conditions much higher altitudes may be achievable.