CASA has responded to criticisms over their advice to broadcast on the area VHF frequency when operating from a airfield not marked on charts.
Former CASA boss Dick Smith highlighted the issue on Friday with a scathing response to advice provided in a Civil Aviation Advisory publication (CAAP).
A CASA spokesperson reiterated the regulator's position in an e-mail sent to Australian Flying.
"The multicom frequency (126.7) is not appropriate here because pilots who are unaware of the unmarked aerodrome will be using the Area frequency, and will not hear multicom broadcasts," the e-mail stated. "Pilots transiting at low levels over uncharted aerodromes will not be monitoring multicom—they could be flying on the same track not knowing traffic is coming up.
"Multicom was never a national frequency—it was the frequency to be used at, or in the vicinity of, non-controlled aerodromes without a discrete frequency.
"The area frequency also has an advantage in an emergency, for receiving ATC alerts, and to receive a surveillance information service (SIS) if required.
"Uncharted aerodromes can be very busy. If you are concerned about frequency congestion, and wish to have an aerodrome charted, the best approach is for the aerodrome owner to work through the local Regional Airspace and Procedures Advisory Committee (RAPAC) to seek a change.
"It is not possible to develop guidance addressing every possible circumstance. This is because radio alerted see-and-avoid in Class G airspace is subject to many variables, not least of which is that not all aircraft will be VHF-radio equipped. So pilots must exercise judgement and airmanship to determine what broadcasts should be made and on what frequency.
"Pilots must check all applicable charts—WAC, VTC, VNC etc. This is important because chart limitations mean that an aerodrome may be marked on one chart but not another."
Smith's objection to the advice is based on the possibility that broadcasts on the area frequency may block out important instructions given to passenger jets.
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