Mode Aviation
Reference No. AR201800046
Date reported 12 May 2018
Concern title Poor radio transmissions of RAAF PC-9’s at Learmonth, WA
Concern summary

Poor transmissions from PC-9 crews resulting in increased workload for civil aviation crews when trying to arrange separation with the PC-9’s.

Industry / Operation affected Aviation: Other
Concern subject type Aviation: Maintenance

Reporter's concern

The reporter expressed a safety concern regarding poor radio transmissions of some Royal Australian Air Force (RAAF) Pilatus PC-9’s at Learmonth, WA.

The reporter has advised that the RAAF periodically deploy PC-9 aircraft to Learmonth, the airspace which, is shared by regular passenger transport and general aviation operators.

The reporter states that radio transmissions from the crew of some PC-9’s are routinely poor and at times unintelligible. The reporter has advised that PC-9 crews have apologised for the poor transmissions and have stated that their radios are 30 years old.

The reporter is concerned that the poor transmissions from PC-9 crews results in an unnecessary increased workload for civil aviation crews when trying to arrange separation with the PC-9’s.

Reporters comment: ‘Being unable to understand RAAF transmissions when needing to establish separation is unsafe and unacceptable’.

Operator's response (Operator 1)

The first incident involved a general aviation operator who complained on the CTAF that one PC-9 was making garbled / mumbled transmissions. Another PC-9 attempted to raise the GA operator to which they responded the second PC-9 was loud and clear. Further communications ensued during which time the comment of the PC-9 radios being 30 years old was mentioned. [Operator] helicopters were on frequency at the time of these interactions.

There was a second incident involving [Operator] helicopters where the crew perceived their departure was delayed due to up to four aircraft recovering into the Learmonth circuit. A brief exchange occurred and the PC-9 aircraft altered his circuit pattern after a request from the helicopter. Although radio communications were loud and clear, some frustration at the delay in departure may have combined with overhearing comments about poor communications and led to the report.

[Unit] has progressively evolved radio operations at CTAF, using Radio 2 to improve radio reception for calls made on CTAF following two safety reports where CTAF calls were missed from other aircraft. However, Radio 2 is a better reception box, but may not be as powerful for transmission. The Commanding Officer has directed a review of this procedure and the relevant risks to ascertain which is the most prudent way for using PC-9 radios in CTAF, noting the strengths and weaknesses of both.

Once this review is complete, any recommended changes will be added to the deployment instructions. These two incidents and the follow up from the ATSB will also be added as advice and guidance for all CTAF operations in the future.

Regulator's response (Regulator 1)

DASA is satisfied that the matter at ATSB REPCON AR201800046 is a valid safety concern, and has been acted upon appropriately by the unit commander.

The DASA intends to:

  • include the subject ATSB REPCON as an artefact for further consideration by the forthcoming annual independent board of review into PC-9 (and unit) operations on 15 Aug 18 (i.e. the Defence Airworthiness Authority’s PC-9 Airworthiness Board for 2018), and
  • recommend to DDAAFS (Defence’s ATSB equivalent) that, if not already done so, the incident is rendered by Defence’s Aviation Safety Report (ASR) system as a discrete event, thereby capturing the lessons learnt for future reference and analysis.
Last update 05 August 2019