The QantasLink radio procedure required Dash 8 flight crews to use the VHF COM 2 radio to broadcast and receive on local frequencies during operations at non-controlled aerodromes. This reduced the ground-based radio transmission and reception strength, and therefore reduced the likelihood of other aircraft receiving calls in some circumstances.
The interchange the use of departure transmissions to VHF COM 1 from VHF COM 2 for Mildura Airport will reduce the risk of pilots of QantasLink and other aircraft missing radio broadcasts on the ground at Mildura.
The ATSB acknowledges that QantasLink has done a risk assessment of the safety issue across all non-controlled aerodromes and that assessment identified additional threats. The ATSB notes, however, QantasLink has not provided an assessment of how these threats are considered to pose a higher risk than the existing aircraft collision risk identified in the safety issue. The ATSB believes that the risk assessment may be benefited by examining aerodromes other than Mildura that exhibit similar risk factors, namely, radio shielding, visual obstructions, and/or multiple runways. Furthermore, the risk assessment did not take into account the newly introduced advice from the aircraft manufacturer in 2 flight operations service letters.
On 17 July 2024 QantasLink fleet safety issued a fleet‑wide technical advisory bulletin (TAB-2024-44) for Mildura Airport, citing changes to the VHF communication procedure only for departures at Mildura. The effective change was to interchange the use of departure transmissions to VHF COM 1 from VHF COM 2. This was to improve ground‑to‑ground common traffic advisory frequency (CTAF) VHF communication quality during taxi and to mitigate the airborne collision risk due to cross runway layout and communication difficulties between runways 09 and 36.
The bulletin further identified VHF radio communication as suspected to be unreliable between runways 09 and 36. It further mentioned the ATSB/ACMA testing and identified improved ground‑to-ground transmission clarity and strength, due to the VHF COM 1 antenna’s location on the top of the fuselage. QantasLink also reviewed a possible new procedure to address the ATSB safety issue concerning communications on local frequencies at all non‑controlled aerodromes via a bowtie analysis.[1] It stated:
Utilising VHF 2 for communications with ATS [air traffic services][2] and reserving VHF 1 for CTAF communications may limit the ability for ATS to be reached when on the ground at some aerodromes without requiring the lower-fidelity HF radio, due to the VHF 2 antenna being located on the underside of the fuselage. Contact with ATS when on the ground is essential for crew to gain an accurate awareness of … traffic movements prior to departure.
The complexity of the procedure may lead to a mismanagement of radio comms swaps and potentially not hearing important traffic information. In addition, this procedure is likely to increase crew workload and subsequent operational errors.
The QantasLink analysis concluded:
The current procedures pose lower number of threats whereas the proposed procedure would introduce three additional threats as well as increase complexities. Whilst intention of having greater safety outcomes is understood, there would be unintended consequences of additional complexity if applied to all CTAF airports.
Additionally, the proposed changes would result in a degradation of several existing controls. Adopting a new procedure which isn’t widely practiced within the aviation industry, adding complexity in the event of a non-normal operation and reducing the crew mental model of traffic within CTAF environments.
On 16 April 2025, Qantas stated:
Following the implementation of the VHF comms swap procedure in Mildura, QantasLink reviewed the opportunity to adopt this procedure at all non-towered aerodromes. Upon completing a detailed risk assessment, it was determined that this change is likely to introduce unintended consequences, such as the ability to maintain effective communication with ATS when on the ground and increased flight crew workload in an already complex CTAF environment. It was also determined that the existing procedure is effective at aerodromes where there is no significant ground radio shielding and the thresholds of active runways are not visually obscured.
As a result of this assessment, it was decided to confine this special procedure to aerodromes with known ground radio shielding and where the thresholds of active runways are visually obscured. At time of writing, Mildura is the only aerodrome in the QantasLink network that has been identified with these characteristics.
The introduction of TAB-2024-44 introduces proactive safety action for Mildura departures, however the ATSB notes this does not encompass Dash 8 operations at other non-controlled aerodromes where Dash 8 radio transmission strength and clarity may be reduced due to the use of ground-based communications on VHF COM 2. The Mildura procedural change demonstrates the effective mitigation of Dash 8 VHF COM 1 departure communication for ground‑based communications, in which consideration to all non-controlled aerodrome operations may be beneficial.
The QantasLink bowtie qualitative risk assessment on the proposed adoption of modified CTAF radio panel usage across all non-controlled aerodromes focussed on additional threats, increased complexities and controls. ATSB acknowledges that the risk assessment identified additional threats. However, QantasLink has not provided an assessment of how these threats are considered to pose a higher risk than the existing aircraft collision risk identified in the safety issue. QantasLink may wish to consider for example:
The risk assessment focus was narrowed from assessing the risk of all airports due to the aircraft shielding to those with known ground shielding and did not quantify the number of affected airports with suspected geographic radio shielding within the network, or the number of airports affected by multiple runway operations and the projected likelihood of these impacts on a procedural change.
As a result, QantasLink considered Mildura as the only affected airport, however the ATSB believes that the risk assessment may be benefited by considering aerodromes other than Mildura that exhibit similar risk factors, namely, radio shielding, visual obstructions, and/or multiple runways (such as those in Appendix C).
Furthermore, the risk assessment did not take into account the newly introduced advice from the aircraft manufacturer in flight operations service letters detailing the limitation of direct line of sight VHF communications and the effects of buildings, terrain or features of the aircraft, such as the vertical stabiliser or landing gear and use of the upper fuselage antenna to provide improved communication in both transmission and reception.
