The ATSB has concluded its investigation into a March 1 2011 stickshaker incident on a QantasLink flight, finding that the aircraft’s computer activated the stall warning on the basis of conflicting inputs from the flight crew.
According to the ATSB report, the captain of the Bombardier Dash 8-300 turned off the icing protection switch as the flight approached Sydney from Tamworth but did not inform the first officer, who was piloting the aircraft, and did not turn off the increased reference speed switch. The reference speed switch is used to set the stall warning to activate at a lower angle of attack — and thus a higher speed — during icing conditions.
After the sitckshaker activated the captain took control of the aeroplane and landed safely at Sydney Airport.
The ATSB said the incident resulted from “individual actions or was specific to the occurrence” and did not indicate the need for changes in flight procedures. However, the safety agency said QantasLink subsequently “undertook a number of safety actions to minimise the rise of a rucurrence.”