Recommendation

SUBJECT



Procedures and facilities to improve the safety of regular public
transport (RPT) aircraft operating within an MBZ or CTAF.





OCCURRENCE SUMMARY



The pilots of two aircraft operating low capacity RPT flights to
Bundaberg received traffic information on a general aviation
instrument flight rules (IFR) aircraft inbound to the aerodrome.
The estimated times of arrival for the three aircraft at the
aerodrome were within a ten minute period. The pilots of the two
RPT aircraft could not establish radio communications with the
other pilot on the published MBZ frequency and could not ascertain
that aircraft's position. The weather at the aerodrome was
instrument meteorological conditions (IMC) requiring the pilots to
conduct instrument approaches.



One of the RPT aircraft landed and the pilot observed the general
aviation IFR aircraft in the circuit. After further attempts to
establish radio communications the pilot was discovered to be
operating on an incorrect frequency.





SAFETY DEFICIENCY



The current procedures for communications in MBZs and CTAFs are
not fail-safe. There are insufficient defences to minimise the risk
to RPT operations of a failure of communications.





ANALYSIS



The procedures to enable pilots operating under MBZ or CTAF
procedures to establish that their radio is transmitting and
receiving on the appropriate frequency are limited to receiving
responses from other aircraft on the same frequency. There are no
other procedures for a pilot to confirm the correct operation of
communication equipment.



Records of reported incidents of a lack of radio calls in MBZs and
CTAFs indicate that between April 1996 and April 1997 there was an
average of 11 incidents per month Australia wide. It could be
expected that this is only a small sample of the communications
failures that do occur. Without a definite response by either a
ground based radio operator or interrogation device, a pilot cannot
be assured that the correct communication channel has been
established.



The operation of regional airlines to aerodromes in which MBZ and
CTAF procedures apply means that fare paying passengers are being
subjected to a reduced level of safety when there are breakdowns of
these procedures.



The problem of operations in MBZ and CTAFs, highlighted by the
incident, was discussed at a meeting attended by the Bureau of Air
Safety Investigation (BASI), Airservices Australia and the Civil
Aviation Safety Authority (CASA) on the 7 June 1997. The meeting
agreed that BASI would frame appropriate recommendations.



Implementation of procedures and facilities that would ensure that
the MBZ and CTAF operations are conducted in a fail-safe manner
would improve the level of safety for airspace users and fare
paying passengers.