The Australian Transport Safety Bureau issued a warning about unnecessary low flying this week in the wake of the fatal crash of a Robinson R22.
VH-KZV struck terrain on a station 125 km north-east of Alice Springs in November 2018, killing the pilot and severly injuring the passenger. The aircraft was completely destroyed.
The ATSB investigation report concluded that the helicopter most likely encountered a standing wave from nearby high terrain when it was less than 150 feet AGL and probably over-loaded. In those circumstances, the ATSB believes the helicopter would not have had enough surplus power to climb against the down flow of air.
"The ATSB found that the collision with terrain was very likely the result of the helicopter encountering a strong downdraft while low flying on the lee side of higher terrain in the MacDonnell Ranges," the investigation report states. "In addition, the ATSB identified a number of factors of increased risk.
"Other factors of increased risk included that it was very likely the helicopter was overloaded and beyond the forward centre-of-gravity limit, which would have reduced the helicopter’s power margin and flight control available to the pilot.
"Secondly, there was moderate turbulence forecast at the time of the accident and the pilot did not check the weather forecast prior to departure.
"Thirdly, the pilot had an elevated level of alcohol in his system, which was capable of impairing his performance, and increased the likelihood of risk-taking behaviour and mishandling the helicopter in an emergency."
A camera recovered from the helicopter showed no footage from the accident flight, but it did show that the pilot had in the past made a habit of contour flying down valleys and river beds.
"At low altitude, there is a lower margin for error due to obstacle avoidance," the ATSB states. "Recognising the risks and hazards of low-level flying, it should be avoided when there is no operational requirement, even if a pilot has been trained and approved to conduct low-level operations."
The full report is on the ATSB website.