Charles Ulm, together with co-pilot George Littlejohn and navigator/radio operator Leon Skilling, were attempting to survey a route from Oakland, California, to Sydney in Airspeed A.S.6 Envoy VH-UXY Stella Australis for his new company Great Pacific Airways. They left Oakland, USA, on 3 December 1934. The flight apparently proceeded normally until nearing the Hawiian islands when the crew became disorientated and were unable to sight land. When their fuel became exhausted, Skilling radioed that Ulm intended to ditch the aircraft. An extensive air and sea search found no trace of either the aircraft or crew.
The Airways Museum & Civil Aviation Historical Society website http://www.airwaysmuseum.com