Close encounter highlights see-and-avoid constraints|Flight Security Australia

The Australian Transportation Security Bureau (ATSB) is advising pilots of the limitations of the see-and-avoid concept after 2 Cessnas were associated with a near accident south-west of Darwin Airport in 2017.

On 6 December, a Cessna 210 (VH-SYT) and a Cessna 206 (VH-HPA) left Darwin Airport in fast succession bound for Port Keats. Both were charter flights running under VFR and planned to track at 8500 feet. Each pilot knew the other aircraft and ATC had advised both pilots of each pilot’s strategies.

The Cessna 210 was the trailing airplane but was travelling faster than the C206. As the two airplane assembled, the pilot of the C206 lost sight of the other airplane. The pilot encouraged ATC that the wing of his airplane was obscuring his view but took no additional action to ensure separation with the other airplane.

The ATSB discovered the airplane had come within 5 metres of each other as they passed. A security alert was just issued by ATC after the near accident due to a combination of radar resolution and the error of the shown height of the C210.

While see-and-avoid is the primary way of avoiding accidents between VFR aircraft, the restrictions of this strategy are well understood.

The ATSB said, ‘this event highlights the troubles of the see-and-avoid principle, even when the pilot is given info about (or signaled to) the other aircraft’s position. Airborne collision avoidance systems (ACAS) innovation can provide important info to alert pilots of other airplane in their distance and can direct the pilot to take avoiding action, consequently decreasing the danger of accident.’

Flight Security Australia took a look at the restrictions of see-and-avoid strategies last year in Unalerted see and prevent it’s not a good appearance and Be seen and be safe.