The Australian Transport Safety Bureau has concluded that the Cessna R172K that crashed near Sutton, NSW, in April 2021 most likely stalled during a steep low-level turn.
VH-DLA was being flown on powerline survey work when it impacted the ground immediately after a left turn. Both the pilot and the observer died in the crash.
According to the ATSB report released last week, data showed the aircraft commenced a left turn to follow a powerline rather than a procedural 270-degree partial orbit to the right to line-up on the transmission line. The ATSB believes that during the left turn the bank angle reached 50 degrees whilst the airspeed decreased to 56 knots. In that configuration, the ATSB calculated the aircraft would have stalled at 57 knots.
Data retrieved from OzRunways EFB showed the aircraft was only 80 feet above the ground just before impact.
“This investigation reinforces to pilots the importance of managing airspeed and bank angle to minimise the risk of stalling,” ATSB Director Transport Safety Stuart Macleod said.
“This is particularly important when operating in close proximity to the ground, such as conducting low-level air work, as well as during take-off and landing, as recovery may not be possible.”
During the investigation the ATSB found that the flaps were extended to the second stage and that the stall warning was functioning at the time of the crash.
The ATSB was unable to determine why the pilot chose to do a left turn when he had conducted several partial orbits earlier in the flight during similar operations.
The full report is on the ATSB website.