Reference number
Date reported
Published date
Affected operation/industry
Concern subject type
Reporter's deidentified concern

The reporter states that while the recent amendment to lower class E airspace to Flight Level (FL)125 has been beneficial; however, remote areas where High Frequency (HF)/Very High Frequency (VHF) communication can be difficult and there is no Automatic Dependent Surveillance - Broadcast / Contract (ADS-B), the lower level of FL125 is problematic. The reporter cited a recent flight from The Granites aerodrome (YTGT), where the crew obtained their initial taxi information and Identification, friend or foe (IFF) code via phone prior to engine start. The crew could not establish HF communications with Air Traffic Control (ATC) either on taxi or departure despite several attempts on multiple HF frequencies. Several attempts at VHF communications to give departure report was made during climb to F125 where aircraft was levelled off to await ATC clearance to enter E space. The crew continued to try multiple HF and VHF frequencies without any success. When the crew did establish contact with centre on 123.6, they were advised that VHF coverage on 118.9 heading north from YTGT does not normally occur until FL150. Additionally, ADS-B identification was not made until FL220.

The reporter states that being unable to make VHF contact had previously not been an issue due to the controlled airspace being at a higher level. However, the blanket change in lowering the Class E airspace level has created a situation that sees at least one remote area, not equipped with the technology to support communication with ATC at that lower level. As clearance from ATC is required to enter E space, if the crew encounter any communication issues, which is not uncommon, flight crew have no choice but to operate at lower altitudes until they reach an area where communications are available, which results in the aircraft utilising much more fuel than intended. The reporter queries if VHF coverage should be available for all controlled space, and why there is no ADS-B receiver at an airport, such as The Granites, which has the power and infrastructure to support an installation.

Named party's response

We appreciate the opportunity to respond to the reported safety concern regarding Lower Level E Space in remote areas without VHF or ADSB coverage. The HF system provides the required two-way communications (Flightwatch) between appropriately equipped aircraft and the unit providing the area control service (Brisbane Centre). The air traffic movements at The Granites are very low and there is insufficient data from customer feedback to Airservices to suggest a systemic problem with HF exists in that area. VHF is provided where practicable for an area control service and where not practicable, Controller Pilot Data Link Communications (CPDLC) and/or HF is provided. Airspace classification does not have any International Civil Aviation Organisation (ICAO) or regulatory requirements for a specific communications system. Surveillance is not an ICAO or regulatory requirement for an Area Control Service (in all classes of airspace).

Separation is provided with procedural separation standards where surveillance (radar and or ADS-B) is not utilised. In the airspace surrounding The Granites prior to the airspace change on 21 May, pilots would have operated in non-surveillance Class E airspace above FL180 until passing FL220 where typically, ADS-B coverage commences in that area. HF operators were regularly relaying ATC clearances to pilots departing The Granites, prior to having established VHF communications and there have been no identified systemic issues regarding the HF service in that area prior to the airspace change on 21 May 2020. In any cases where aircraft are unable to establish HF contact to relay a clearance to and from the applicable area control service the use of the IFR Pick Up procedure, as outlined in Aeronautical Information Package (AIP) and Manual of Air Traffic Services (MATS), “whereby a flight operating to the IFR in Class G airspace changes to VFR upon entering Class E airspace whilst awaiting an airways clearance” is an alternative option available for pilots.

Regulator's response

Documentation provided by Airservices to support the Airspace Change Proposal (ACP) to lower Class E airspace, identified potential gaps in VHF and ADS-B coverage in a number of areas in Western Australia (including the Granites).

Airservices advised ’There will be some areas of the lowered Class E airspace where Very High Frequency (VHF) communications coverage will not be available. In these volumes separation services to IFR aircraft will require the use of High Frequency (HF) communications. This is an existing practice and Airservices has the required facilities and experience to enable its application in the reclassified airspace. In addition, Airservices maintains a program of monitoring the requirement for additional VHF coverage and if considered necessary additional VHF ground stations can be installed.’  CASA was satisfied that alternative means of communication were available to enable pilot to ATC communication and this issue did not generate an unacceptable risk to aviation safety. CASA expects Airservices will monitor issues related to poor VHF coverage and install additional VHF ground stations if necessary to achieve an acceptable level of safety.

The Safety Case also acknowledges that ‘There will also be some areas of the lowered Class E airspace where ADS-B surveillance coverage will not be available. In this airspace IFR separation services will be provided using established procedural separation standards. CASA was satisfied that an acceptable level of safety could be provided through the use of procedural separation until future surveillance coverage is available”.

Airservices ADS-B Coverage Operational Requirements document (Version 3.0 – Effective 6 December 2018) did not identify any issues with ADS-B coverage below FL 180 in the vicinity of The Granites aerodrome.

Whilst the use of the IFR pick up procedure is available to IFR aircraft, Airservices should be aware that the major airlines will not permit their aircraft to operate VFR at any time. This is in line with ICAO recommendations and globally accepted best practice. Therefore, IFR pick up is not an option to mitigate the issue related to IFR aircraft obtaining a clearance to enter controlled airspace.