The ATSB has found that the Hamilton Island accident in which six people died was the result of a low altitude stall. The tragedy provides an important opportunity to highlight some dangers to flight safety including post-alcohol impairment, cannabis, and fatigue.
At about 5pm on 26 September 2002, Piper Cherokee Six registration VH-MAR crashed shortly after take-off from runway 14 at Hamilton Island heading for the neighbouring Lindeman Island. The pilot and five passengers were fatally injured, and the aircraft was destroyed by impact forces and the post-impact fire.
The final ATSB investigation report has found that the aircraft's engine began operating abnormally soon after take-off, the pilot initiated a steepening right turn at low level, and the aircraft stalled at a height from which the pilot was unable to effect recovery.
The reasons for the engine problems and for why the pilot undertook such a turn could not be conclusively established due to a lack of evidence. It is possible the steepening right turn over land was linked to inadequate training and/or pilot physiological factors.
Previous pilot use of cannabis was evident from toxicology tests, and he had consumed alcohol the night before, had taken panadeine, and had less than 7 hours sleep, but there was insufficient evidence to definitely link these factors to the accident. But the possible adverse effects on pilot performance of fatigue, recent cannabis use, and post-alcohol impairment linked to 'Coriolis' and 'G-excess' phenomena could not be discounted.
In the interests of future safety the ATSB is also releasing aviation research papers on the effects of alcohol and cannabis on pilot performance and other flight safety. While alcohol's effects are relatively well known, research on cannabis is mainly based on 10mg THC doses in reefers typical from the 1960s rather than the 150mg more typical today and the safety effects of smoking cannabis may continue well beyond 24 hours.
The ATSB has issued three recommendations which address the potential use of alcohol and drugs by aviation personnel where there is a safety risk to the travelling public.
The ATSB has also issued to CASA a recommendation on Air Operator Certificate Safety Trend Indicator surveillance methodology, and safety advisory notices relating to pilot manipulation of the Cherokee Six fuel selector, and to development by operators of pilot induction training programs that reflect particular operational risks.
The operator has initiated a number of safety actions including pilot retraining covering engine failure over water, fatigue and work schedule management, use of full runway length for all take-offs, and amendment of the flight operations manual where required.
The reports are available from the website Piper Aircraft Corp PA-32-300, VH-MAR Hamilton Island, Aero., Qld