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Mode Aviation
Reference No. AR201300097
Date reported 27 November 2013
Concern title VHF communications on the ground at Broome airport
Concern summary

The concern related to the lack of VHF reception on the ground at Broome Airport.

Industry / Operation affected Aviation: Air transport
Concern subject type Aviation: Airport

Reporter's concern

The reporter expressed a safety concern regarding VHF communications on the ground at Broome airport.

The reporter advised that recently an incident occurred on the ground at Broome Airport which, without the intervention of a third aircraft, could have resulted in a mid-air collision. Both of the aircraft involved had made all the required radio broadcasts and visual inspections of the runways and approach, but due to the curvature of the Broome runway, did not know that they had lined up on reciprocal runways. As one aircraft made a rolling call a third aircraft broadcast a warning of the conflict and the rolling aircraft rejected the take-off.

The issue of VHF communications not being heard at opposite ends of the runway is a known issue at Broome Airport and to date no steps have been taken to fix the issue. The reporter is concerned that it will take an accident before action is taken and a VHF repeater is installed on the airport.

Operator's response (Operator 1)

Airservices Australia (Airservices) appreciates the opportunity to respond to the reported concern regarding VHF communications on the ground at Broome Airport.

Due to the de-identified nature of the report, Airservices is unable to comment on the specific circumstances of the reported occurrence. However in order to address the reporter's concern Airservices has investigated the matter and can provide the following commentary.

While it is unclear from the report when the occurrence took place, Airservices notes that as of the March 2010 edition of the En Route Supplement Australia (ERSA), additional information has been provided to pilots informing them of the possibility of poor radio propagation in the common traffic advisory frequency (CTAF) area on the ground (see ERSA - Broome/INTL- Additional Information Note 2). This arrangement is similar to other sites (e.g. Amberley) which have experienced CTAF issues on the ground and provides pilots with increased awareness of operational considerations thereby allowing them to consider alternative arrangements (e.g. monitoring the Broome Aerodrome Frequency Response Unit (AFRU)).

Airservices can confirm that there have been no reported faults with Airservices' VHF equipment at Broome Airport since July 2013.

Airservices would like to note that if both aircraft had been operating on Instrument Flight Rules (IFR) then Air Traffic Control (ATC) would have provided mutual traffic information on the Flight Information Area (FIA) frequency during taxiing thereby overcoming any potential VHF communication issues.

With regards to the reporter's suggestion that a "VHF repeater" may potentially solve the issue, Airservices clarifies that single-frequency repeaters are only technically suitable where there is no overlapping coverage. The reported issue is likely caused by the effect of the local topography on direct aircraft-to-aircraft VHF communications on opposite ends of the Broome Airport runway. If a VHF repeater was installed at Broome Airport, the repeater would broadcast over the top of the original call thereby making the broadcast inaudible.

Regulator's response (Regulator 1)

CASA has reviewed the REPCON and due to the de-identified nature of the report it is difficult to determine what the circumstances were that led to the potential conflict. Generally, there is a preferred runway in use due to the prevailing wind, however calm wind conditions may make either runway direction suitable. It is not known if this is what transpired in this instance.

To determine if there is a valid issue in relation to ground communications at Broome Airport outside of tower hours, CASA would need further information to identify the root cause of the problem, including whether procedures such as those in CAR166 were followed correctly, before undertaking further work on a solution. It would be appreciated if further information were provided on the following issues:

  1. Does the report refer to CTAF operations as this is not clear.
  2. Was the AFRU working?
  3. Were any broadcasts made on the area frequency?
  4. What were the flight rules of the three aircraft involved?


ATSB comment

REPCON supplied the following information to CASA as requested

Answers to your questions as follows:

  1. Yes it was CTAF operations at the time.
  2. No answer on this.
  3. Aircraft 1 was IFR and had made the required broadcast on area frequency, but as the other aircraft were VFR no broadcasts were made on the area frequency – nor were they required to be.
  4. Both aircraft had been in communication before the incident. Both had made broadcasts on the CTAF that they were taxiing and the reporter (aircraft 1) states that they broadcasted an entering and line up call for runway 28 and visually checked the runway before entering. They then made a rolling call.

The other aircraft has reported that they made an entering and backtracking call for runway 10 before aircraft 1 called , ie they were already backtracking before aircraft 1 called entering and lining up. They did hear the entering call from aircraft 1 and responded that they were backtracking. This call and subsequent calls to the 3rd taxiing aircraft, and a broadcast that they were holding at the threshold of runway 10 were not heard by aircraft 1.

Aircraft 3 then warned aircraft 1 that there was an aircraft on runway 10 threshold and aircraft 1 rejected the take-off and taxied clear of the runway.

All aircraft were on the CTAF.

No response has been received from CASA in regards to this information.

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Last update 19 June 2014