What happened
On 16 September 2021, a Boeing 737, registration VH-YIO, was on final approach to runway 24 at Ballina Byron Gateway Airport. Simultaneously, a Cessna Caravan 208, registration VH-YMV, began its takeoff roll on the reciprocal runway. As the two aircraft moved toward each other, the lateral separation dropped to approximately 0.9 NM, with vertical separation decreasing to roughly 7 and 700 feet. To avoid a collision, the crew of the Boeing 737 was forced to execute a missed approach.
The investigation
The investigation revealed that the pilot of the Cessna Caravan 208 had formed an incorrect assumption that the arriving aircraft would land on runway 06, based solely on observing the windsock. This incorrect mental model was not corrected because the surveillance flight information service (SFIS) controller failed to specify the landing runway direction or the estimated landing time when providing traffic updates. Furthermore, the pilot did not verify this assumption through direct communication with the controller or the other aircraft.
On the arriving aircraft, the crew did not hear the taxiing broadcasts from the Cessna Caravan 208 or the controller's responses, leaving them unaware of the departing aircraft until the takeoff roll had already begun. The SFIS controller noted that the Boeing 737 had not acknowledged the taxiing traffic, but chose not to follow up, believing further communication was unnecessary for aircraft already on the common traffic advisory frequency.
Additionally, the investigation found that the controller did not issue a safety alert despite recognizing the potential conflict. This decision was driven by a desire to avoid over-transmitting on the frequency. The situation was further complicated by technical limitations; because the aircraft were below 1,500 feet, the controller had no radar or ADS-B positional data for the Cessna Caravan 208 and was forced to rely entirely on radio reports.
Findings
- The pilot of the Cessna Caravan 208 relied on an incorrect assumption regarding runway usage, which was reinforced by confirmation bias during a visual check.
- The failure to communicate the specific landing runway direction by the SFIS controller prevented the correction of the pilot's incorrect mental model.
- Surveillance coverage limitations meant the controller lacked positional information for the departing aircraft until it climbed above 1,500 feet.
- The Boeing 737 crew remained unaware of the departing traffic due to not hearing the initial taxiing transmissions.