The pilot was visiting Karratha on business in his twin engined aircraft and he agreed to a request to take a friend and another local resident for a flight in the Karratha area. The three men met at Karratha aerodrome and at about 0945 hours, before proceeding to the aircraft, the pilot advised the Flight Service Officer on duty at Karratha that he would be making a local flight. Written details are not required for such flights and none were submitted. The pilot also advised that he did not require a radio watch to be kept on the «;ht for search and rescue purposes. At 0958 hours the pilot reported to the Karratha Flight Service Unit by radio that the aircraft was taxying for a local flight and that Runway 08 would be used for take-off. There was no further communication with the aircraft.