The flight crew of a Dash 8 turboprop airliner that taxied onto the runway in front of a light aircraft on approach to land at Gladstone Airport had not selected the appropriate radio frequency and transponder mode which significantly degraded their situational awareness, a new ATSB investigation report details.
On 17 March 2020 at about 6.00 am, the flight crew of the QantasLink Bombardier Dash 8-402 commenced pre-flight preparations for a 6.45 am flight to Brisbane. During those preparations the crew twice started the aircraft’s APU (auxiliary power unit), which failed on both occasions when selecting APU bleed air ‘ON’ to provide air-conditioning to the cabin. The captain also had to review paperwork and brief cabin crew on arrangements for a ‘person in custody’ and their police escort to travel on the flight.
After applying the Minimum Equipment List (MEL) to the APU, the flight crew undertook the remainder of their pre-flight checks, but missed setting the traffic collision avoidance system (TCAS)/transponder to ‘ON ALT’ and selecting the Gladstone common terminal advisory frequency (CTAF) radio frequency.
The first officer identified the CTAF omission during the departure briefing, however incorrectly set the frequency to 126.7 MHz instead of 118.8 MHz, which was the correct frequency for the Gladstone CTAF.
“The ATSB’s investigation found that the flight crew of the Dash 8 had inadvertently selected the incorrect radio frequency for the airport’s CTAF and incorrect mode on the traffic collision avoidance system/transponder during the before start checks reducing the flight’s crew situational awareness and mental model of traffic,” said ATSB Director Transport Safety Stuart Macleod.
“The frequency selection error was further compounded by the flight crew not recognising the absence of the aerodrome frequency response unit reply when making radio calls on the incorrect frequency and the assumption they would be alerted to the presence of any transponder-equipped aircraft that were operating in the area.”
At about 6.45 am, the Dash 8 was taxied onto the runway in front of the approaching light aircraft. In response, the instructor on board the light aircraft commenced a go-around and attempted, unsuccessfully, to contact the Dash 8 crew on the Gladstone CTAF.
Shortly afterwards, the captain identified that the TCAS/transponder was not appropriately set and selected it to ‘ON ALT’. The TCAS subsequently presented the flight crew with a traffic advisory indicating climbing traffic, which was the light aircraft that the flight crew subsequently sighted climbing in an easterly direction overhead the airport.
Mr Macleod said that the incident illustrates the human factors implications associated with the combination of increased workload and time pressures.
“Situations like this can result in degraded information processing, increased errors, the tunnelling of attention, and an increased reliance on familiar strategies or actions and probably resulted in the flight crew’s omission of the two ‘before start’ checklist items and the selection of the incorrect frequency,” he said.
“Flight crews can guard against similar situations by applying effective threat and error management strategies that recognise when such threats may arise and set in place suitable actions that minimise error potential.
“These actions include strict adherence to standard operating procedures and increased cross-checking of system inputs and mode changes.”
As result of the incident, QantasLink has reviewed its operating procedures at non-controlled airports and introduced new requirements to contact air traffic control before entering the runway.Last update 23 February 2021