Recommendation

SUBJECT



Radiotelephony procedures for aircraft operating in non-controlled
airspace



OCCURRENCE SUMMARY



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.



SAFETY DEFICIENCY



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.



ANALYSIS



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.



Conclusion



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.