The pilot was attempting a normal night takeoff in light drizzle, with 7 to 10 knots of crosswind at the time of the accident. As the aircraft lifted off heavy rain started to fall. The aircraft appeared to accelerate normally to 120 knots. As the pilot completed the after takeoff checks he noted that the aircraft was descending at 200 feet per minute instead of climbing, although the nose of the aircraft was 10 degrees above the horizon. The pilot raised the nose still further and reduced the speed to 110 knots, however, this did not stop the aircraft from descending. At 510 feet indicated on the altimeter, the airfield elevation, the pilot levelled the aircraft and prepared for ground impact. The aircraft touched down, gear up, 3 km from the DEPARTURE end of the runway and slid to a stop in flat marshy country. The meteorological station at Forrest reported that during the aircraft's takeoff, the intensity of the rain increased and the surface wind swung around to give a 30 knot tailwind. During test flights prior to and after the accident the pilot-in-command was assessed as having slow cross reference skills and poor attitude control. It is possible that the pilot's performance contributed to the accident.