HIAPER, the nation’s most advanced research aircraft has taken flight on its first science mission, flying over treacherous whirlwinds, known as rotors, as they form above the California Sierra Nevada range. Rotors form on the lee side of high, steep mountains and have contributed to a number of aircraft accidents, but scientists know little about their structure and evolution. Now, the high-altitude, long-range capabilities of HIAPER make possible the study of the origin and evolution of rotors, potentially leading to safer flying.