The late departure of a VFR Cessna 206 from Archerfield in July caused an ATC terrain alert, according to an ATSB investigation report released this week.
VH-ARS departed from Archerfield on a VFR dual training flight close to last light, but on climb-out was unable to reach the minimum safe altitude before official last light, triggering the terrain alert.
With last light at 1739, the crew of ARS requested their transponder code at 1733, which Centre provided, then queried if the aircraft would depart before last light. The crew responded they would do so, and were happy to depart VFR. However, the aircraft did not enter the runway until 1736.
Because Archerfield Tower was closed, the pilot made a departure call on CTAF and, at 1737 reported to Centre that they were airborne in a right turn towards the Walter Taylor Bridge. Centre acknowledged their airborne report and instructed them to verify their altitude and remain OCTA, to which the pilot reported they were passing 400 ft on climb to 1000 ft. At 1738, Centre instructed them to contact Departures for their clearance to enter CTA.
ATC cleared them to climb to 3000 initially, followed by a clearance to climb to 4000. At 1739:06, a minimum safe altitude warning (MSAW) activated for the aircraft on the ATC radar display. At 1739:35, the ATC radar indicated the aircraft was at 1200 ft and Departures issued the pilot with a terrain alert due to the aircraft operating below the 2900-ft minimum altitude in their area after last light.
The instructor on board ARS reported to ATC investigators that they were aware of a history of delays for IFR departures from Archerfield, and that they believed ATC preferred them to depart VFR and then request a change to IFR.
“Despite the IFR plan, the instructor elected to conduct the VFR Northern departure instead of conducting an IFR departure,” ATSB Director of Transport Safety Stuart Macleod said.
“While it was feasible that the aircraft would reach the required minimum altitude before last light based on their flight plan departure time of 1730, take-off actually occurred 7 minutes later than what was flight planned.”
Macleod said the incident highlights the importance of planning, particularly around times of day when rules change, such as the transition from day to night.
Airservices Australia said that its Manual of Air Traffic Services prohibits vectoring aircraft OCTA except when warranted by an emergency, and that the Brisbane local procedures prohibit use of the Archerfield radar SID outside of tower hours.
Investigators also found that IFR arrivals to Brisbane International runway 01R pass overhead Archerfield at 3000 feet, which is the same altitude ATC need IFR departures from Archerfield to climb to in the circling area before departing.
Airservices Australia said it is developing a procedural SID for Archerfield that will be available all hours. The project began in 2019 to facilitate improved deconfliction of IFR departures from Archerfield with IFR arrivals to Brisbane runway 01R.
The full report is on the ATSB website.