On 1 March 2011, a QantasLink Bombardier Inc DHC-8-315, registered VH-TQL, was conducting a regular public transport flight from Tamworth Airport to Sydney Airport, New South Wales. The crew were conducting a Sydney runway 16 left (16L) area navigation global navigation satellite system (RNAV(GNSS)) approach in Vertical Speed (VS) mode. The aircraft's stickshaker stall warning was activated at about the final approach fix (FAF). The crew continued the approach and landed on runway 16L.
The stickshaker activated at a speed 10 kts higher than was normal for the conditions. The stall warning system had computed a potential stall on the incorrect basis that the aircraft was in icing conditions. The use of VS mode, as part of a line training exercise for the first officer, meant that the crew had to make various changes to the aircraft's rate of descent to maintain a normal approach profile.
On a number of occasions during the approach the autopilot pitched the aircraft nose up to capture an assigned altitude set by the pilot flying. The last recorded altitude capture occurred at about the FAF, which coincided with the aircraft not being configured, the propeller control levers being at maximum RPM, and the power levers at a low power setting. This resulted in a continued speed reduction in the lead-up to the stickshaker activation.
Each factor that contributed to the occurrence resulted from individual actions or was specific to the occurrence. The Australian Transport Safety Bureau is satisfied that none of these safety factors indicate a need for systemic action to change existing risk controls. Nevertheless, the operator undertook a number of safety actions to minimise the risk of a recurrence.
In addition, the occurrence highlights the importance of effective crew resource management and of the option of conducting a go-around should there be any doubt as to the safety of the aircraft. Transport Canada, which regulates the aircraft manufacturer, advised that it will publish a summary of this occurrence and recommend that operators consider using it in their scenario-based crew resource management training programs.
|Date:||01 March 2011||Investigation status:||Completed|
|Time:||1810 EDT||Investigation level:||Complex - click for an explanation of investigation levels|
|State:||New South Wales||Occurrence type:||Stall warning|
|Release date:||28 May 2012||Occurrence class:||Operational|
|Report status:||Final||Occurrence category:||Incident|
|Highest injury level:||None|
|Aircraft manufacturer||Bombardier Inc|
|Type of operation||Air Transport High Capacity|
|Damage to aircraft||Nil|
|Departure point||Tamworth, NSW|