A pilot's incorrect mental model and communication breakdowns led to a situation where a Caravan pilot took off into the path of a landing B737 at Ballina, according to the ATSB investigation report released yesterday.
On 16 September 2021, Cessna Caravan VH-YMV departed Ballina Byron Gateway Airport on runway 06 whilst a Virgin B737 was on final approach to runway 24. The crew of the Boeing executed a missed approach and received a Traffic Collision Avoidance System (TCAS) advisory on the Caravan.
The Caravan turned right and circled to cross the nose of the B737 as it took up a track for Sunshine Coast. The two aircraft passed within 0.9 nm and 700 feet of each other. The Boeing crew kept visual contact with the Caravan as they set-up for another approach.
Although Ballina is a CTAF, it also has an overlying Surveillance Flight Information Service (SFIS) over it, operating from Brisbane. The SFIS controller did not issue a safety alert to the pilots due to a fear of over-transmitting the two aircraft.
"The ATSB’s investigation identified that the Caravan pilot had an incorrect mental model of the traffic scenario, believing the 737 would land behind them on runway 06, rather than runway 24,” said ATSB Director Transport Safety Stuart Macleod.
“The Caravan pilot had been provided with traffic information by the Ballina Airport surveillance flight information service controller, but the controller had not specified the landing direction of the 737 and the pilot had not sought this information.
“The scenario was further compounded by the flight crew of the 737 not hearing the initial communications from the Caravan pilot, or the SFIS controller's response, and the flight crew remained unaware of the Caravan until just prior to it entering the runway.”
SFIS controllers use ADS-B data and radio broadcasts on CTAFs to provide aircraft with traffic information and alerting services, but the controller does not provide a separation or sequencing.
Ballina's SFIS went live in August 2021, but the ATSB also found that the SFIS had been implemented in an area with known surveillance coverage limitations.
Airservices Australia has advised the ATSB that a new ADS-B ground station to improve surveillance coverage at Ballina Airport was scheduled for installation in March this year.
An Office of Airspace Regulation (OAR) review into Ballina airspace in June last year recommended that Airservices Australia establish a Class D control tower at Ballina Byron Gateway Airport no later than 30 November 2023.
The full investigation report is on the ATSB website.