Safety Advisory Notice SAN19980018

Safety Advisory Notice issued to: Civil Aviation Safety Authority

Recommendation details
Output No: SAN19980018
Date issued: 26 February 1998
Safety action status: Closed


Radiotelephony procedures for aircraft operating in non-controlled airspace


An instrument flight rules (IFR) Cessna 402 (C402) and an IFR Cessna 310 (C310) were tracking in opposite directions on the same route and were maintaining 10, 000 ft and 7,000 ft respectively. Both aircraft were in cloud between reporting points Sevsi and Seemo and were using high frequency (HF) radio to communicate with Perth Flight Service (FS). The pilot in command (PIC) of the C402 requested traffic information from FS for descent due to icing conditions. However, HF communications were difficult and the PIC was unable to obtain the information prior to requiring to descend. The PIC stated that he broadcast his intention to descend to 6,000 ft on the HF and the very high frequency (VHF) radios. However, the VHF report was not heard by the PIC of the C310. Eventually, FS advised traffic information on the C310 to the PIC of the C402. The subsequent exchange of position reports by the pilots indicated that the C402 had passed through the other aircraft's level while they were in close proximity.


Instructions in the Aeronautical Information Publication (AIP) regarding the requirement for radiotelephony reports on both HF and VHF radios, while operating in non-controlled airspace, are inconsistent and are not included in all the appropriate sections of the publication.


During the investigation of the occurrence, the AIP was reviewed to ascertain the requirements for VHF area broadcasts by pilots of IFR aircraft, communicating on HF, while operating in non-controlled airspace. The review found three references relating to these requiremets. Within these references, the requirements for dual (VHF and HF) broadcasts were found to be inconsistent or were not included in some sections of the AIP.

AIP Air Traffic Rules and Services (RAC)

AIP RAC 61 paragraph 43.2.6 details the requirement for dual broadcasts for IFR flights and states "When a report from an IFR aircraft is made to FS on HF, a broadcast on the appropriate MBZ frequency, CTAF or area VHF is also required."

Another reference is included in the RAC 63, Summary of Reports and Broadcasts - IFR Aircraft Outside Controlled Airspace (Class G) table. However, this reference states that dual reports are only required by "aircraft about to leave controlled airspace". This is inconsistent with RAC 61 as there are a number of other reports listed in the table that would also require dual broadcasts in accordance with RAC 61. Inclusion of a cross-reference to RAC 61 or the addition of a note after the table detailing the requirement for dual broadcasts following all mandatory reports, would clarify radiotelephony requirements and would be consistent with RAC 61.

AIP Operations (OPS)

AIP OPS, Operations at Non-Controlled Aerodromes (NCTL) 9 paragraph 58, refers to radiotelephony requirements outside controlled airspace. However, the requirement for dual (HF and VHF) broadcasts is not referred to in this paragraph.

Inclusion of RAC 61 paragraph 43.2.6, or a reference to this paragraph and/or the table in RAC 63, would assist pilots to more readily access the pertinent information in the AIP.


RAC 61 paragraph 43.2.6 clearly states the requirement for dual broadcasts on all occasions when a mandatory report is required. RAC 63 indicates a much more limited requirement for dual broadcasts, and OPS 9 paragraph 58 does not refer to this requirement at all. The complete and consistent presentation in the AIP of radiotelephony requirements for flight in non-controlled airspace would help to ensure the correct understanding and use of these procedures. This, in turn, may assist in reducing the risk of traffic conflict occurrences between aircraft operating in non-controlled airspace.

Output text

The Civil Aviation Safety Authority should note the safety deficiency identified and take appropriate action.

Initial response
Date issued: 14 May 1998
Response from: Civil Aviation Safety Authority
Response text:

I refer to your BS/970094 of 26 February 1998 covering Safety Advisory Notice SAN980018.

CASA has reviewed the information provided in the Safety Advisory and will amend AIP as BASI has proposed.

Last update 01 April 2011