Although following standard pre-flight checks and crosschecks, the crew of a Dash 8 did not identify that the wrong flap setting was selected for a performance-limited take-off from Horn Island, an ATSB investigation details.
During their pre-flight preparations for a QantasLink passenger flight from Horn Island to Cairns on 26 June 2024, the flight crew determined the take-off would be performance-limited due to the shorter runway length available at Horn Island (1,389 m), and a full passenger load.
As such the crew determined a flap setting of 15° (flap 15) would be required for the take-off. But when setting the flaps, the first officer inadvertently selected 5° (flap 5).
"This was likely due to habitual behaviour, given flap 5 was the flap setting on the two prior take-offs, and the most common for other sectors in the network," ATSB Director Transport Safety Dr Stuart Godley said.
"Although the crew conducted standard pre-flight checks and crosschecks, they did not identify the incorrect flap setting before take-off, likely due to their automatically registering flap 5 to be the usual take-off setting."
The aircraft accelerated normally during the initial take-off run, however the crew noticed the aircraft's rotation was slow, and that aircraft performance was not what they would normally expect at the start of the climb.
"The first officer's application of continued back pressure to the controls resulted in the aircraft becoming airborne slightly after the expected rotation speed," Dr Godley continued.
"The FO then identified the flap 5 setting, and immediately advised the captain, who instructed them to continue to fly the aircraft."
The first officer subsequently lowered the nose to increase airspeed, and the aircraft accelerated. A positive rate of climb was maintained and the flight proceeded to Cairns without further incident.
The ATSB investigation's final report notes the incident is a reminder of the potential effect of high workload encountered by flight crews during preparation, taxi and take-off phases of flight.
"This incident reinforces to pilots the importance of always carefully verifying and methodically completing checks and checklists to minimise the risk of unnoticed errors," Dr Godley said.
"Maintaining focus and staying mindful of potential deviations to usual settings is essential during periods of high workload for safe operations."
Following the occurrence, QantasLink implemented a review of standard operations procedures to reduce the likelihood of erroneous flap selection, a review of relevant checklists, and training for crew focused on standard operating procedures and compliance.
You can find here the report: Incorrect configuration involving Bombardier DHC-8-402, VH-QOI, at Horn Island Airport, Queensland, on 26 June 2024
