What happened
During an operation at an aerodrome, an aerodrome controller (ADC) issued a take-off clearance to the helicopter VH-FOA that contradicted the controller's original separation plan. While the controller intended for the helicopter to depart in the runway 30 direction, the instruction provided directed the aircraft to take off toward runway 12, the opposite direction. This error went unnoticed by the controller and other personnel until the crew of VH-FOA observed the aircraft XZP touching down ahead of their flight path. The instructor subsequently reported the incident to air traffic control.
Although the timing and positioning of the aircraft meant the crew did not need to perform significant maneuvers, the incident resulted in a loss of runway separation assurance. Additionally, a conflict was identified between VH-FOA and a taxiing B737.
The investigation
The investigation focused on why the incorrect clearance was issued and why the error was not caught immediately. It was found that the ADC became preoccupied with coordination tasks with the approach controller immediately after issuing the clearance. Because the controller was focused on these tasks, they were not visually observing the departure of VH-FOA.
Furthermore, while the controller's intended plan was noted on the flight progress strip, the controller did not refer to this strip. The student pilot performed a read-back of the incorrect clearance, but the ADC did not identify that the instruction given deviated from the intended plan. The investigation also noted that the controller did not habitually annotate the strips, which deprived them of a secondary cue to detect the mistake.
Findings
- The ADC issued a take-off clearance to VH-FOA that was contrary to the intended separation plan.
- The error was caused by the ADC becoming preoccupied with coordination tasks with the approach controller.
- The controller failed to refer to the flight progress strip which contained the correct intended instruction.
- The controller did not notice the student pilot's read-back contained the incorrect direction.
- The controller did not use strip annotation as a method to confirm or verify instructions.