Separation incident highlights importance of understanding traffic positions and intentions in CTAF operations

The position of the aircraft in the area in relation to Sunshine Coast Airport

A separation incident occurred when an Airbus A320 airliner and an Aero Commander 500 piston twin light aircraft were on converging flight paths when operating to and from reciprocal runways at Sunshine Coast Airport, an ATSB investigation details.

The incident occurred at about 6:35am on 4 November 2019, outside the operating hours of the airport’s air traffic control tower, and so Class G (uncontrolled) airspace procedures were in place with the pilots using radio broadcasts on the common terminal advisory frequency (CTAF*) to ensure sequencing and mutual separation with other aircraft. The A320 was on approach to land on runway 18 while the Aero Commander was departing from the reciprocal runway, runway 36.

“The ATSB found that the A320 flight crew and the Aero Commander pilot did not hear important CTAF radio broadcasts made regarding each other’s position and intention,” said ATSB Executive Director Transport Safety Nat Nagy.

“These included the inbound broadcasts made by the A320 and the take-off broadcast made by the Aero Commander.”

Mr Nagy noted the Aero Commander pilot likely had yet to turn the radio on at the time the A320 flight crew made their inbound radio broadcasts. The A320 flight crew, meanwhile, did not hear the rolling for take-off broadcast made by the Aero Commander pilot, which occurred at the same time as Brisbane Centre was contacting the A320 on the Brisbane Centre frequency. (Brisbane Centre was providing a traffic information service.)

When operating in uncontrolled airspace to and from non-towered aerodromes, it is important that pilots ensure that the location and intention of surrounding traffic is well understood and communicated prior to commencing take-off or landing.

The two aircraft established direct communications with each other when the A320 first officer broadcast on the CTAF that they were turning on a five (nautical) mile final approach for runway 18 and asked if the Aero Commander pilot was holding short of the runway. The Aero Commander pilot responded as being airborne, that the A320 was in sight, and the intention to track to the A320’s left (by making a right turn).

The aircraft passed each other with a recorded separation of 0.7 nautical miles horizontally and 265 feet vertically. The A320 landed at Sunshine Coast Airport and the Aero Commander continued to Maryborough without further incident.

The ATSB investigation noted that the A320 flight crew elected to use runway 18 for landing after listening to the aerodrome weather information service radio broadcast. However, this was either incorrectly recorded or they misheard the wind conditions, as runway 36 was instead the more suitable runway based on the actual wind at the airport. This resulted in the A320 approaching the opposite runway to that being used by other aircraft at the time.

The investigation also found that the Aero Commander pilot did not confirm the location and intention of the inbound A320 prior to commencing take-off, on the assumption that the A320 would use the most suitable runway for the wind conditions.  

“This investigation highlights that when operating in uncontrolled airspace to and from non-towered aerodromes, it is important that pilots ensure that the location and intention of surrounding traffic is well understood and communicated prior to commencing take-off or landing,” Mr Nagy said.

 A number of resources are available to pilots operating in non-controlled airspace including the ATSB publication A pilot’s guide to staying safe in the vicinity of non-controlled aerodromes and the Civil Aviation Safety Authority’s ‘be heard, be seen, be safe’ resource booklet, Mr Nagy noted.

* Pilots operating at non-towered aerodromes are expected to make a series of standard broadcasts on the CTAF regarding their position and intentions. Broadcasting on the CTAF reduces the risk of a mid-air collision or reduced separation by supporting pilots’ visual lookout for traffic and situational awareness, and assists them to mutually separate their aircraft. This is known as radio-alerted ‘see-and-avoid’.

Read the investigation report AO-2019-062: Separation issue involving Airbus A320, VH-VQG, and Aero Commander 500, VH-UJS, near Sunshine Coast Airport, on 4 November 2019

Last update 10 June 2020

Final report

AO-2019-062: Separation issue involving Airbus A320, VH-VQG, and Aero Commander 500, VH-UJS, near Sunshine Coast Airport, on 4 November 2019