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VHF radiocommunications

VHF transmitter licensing

Rev. 12a — page content was last updated 28 April 2011
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The Australian Communications and Media Authority provides a class licence which authorises a person to operate an aircraft station or aeronautical mobile station if the person complies with the conditions in the class licence. The recreational aviation administration organisations (RAAO) VHF radio operator endorsements* are a certification that the person has demonstrated that he/she has reached the qualification standard acceptable to the Authority for operation of a VHF aircraft station or aeronautical mobile station.

*Note: the RAAOs cannot issue endorsements for operation of HF transceivers and a person must hold a CASA flight radiotelephone operator licence, granted under Part 5 Division 3 of CAR 1988, if he or she makes airborne radio transmissions on any of the 16 aviation HF frequencies.

1.1 The aircraft station and aeronautical mobile station class licence

All operational radio transmitters are required to be licensed by the Australian Communications and Media Authority [ACMA]. To avoid the need to license individual VHF and HF aviation radiotelephony transceivers (and other transmitters carried in aircraft such as transponders or radio distress beacons) the ACMA issues a class licence. The current Radiocommunications (Aircraft and Aeronautical Mobile Stations) Class Licence 2006 [CL2006] replaced the Radiocommunications (Aircraft Station) Class Licence 2001.

CL2006 authorises the operation — by qualified operators — of a range of aeronautical radiocommunications and radionavigation equipment fixed to, or carried on board, all aircraft including recreational aircraft. It also authorises most ground-based aeronautical mobile radiocommunications equipment operating on the common group of aviation frequencies.

An aircraft station may only be operated (i.e. transmitting) when it is on board an aircraft, thus you cannot operate your hand-held transceiver as an aircraft station unless you are in an aircraft and identify yourself with that aircraft's station call sign. If any condition of CL2006 is breached (for example, transmitting on a frequency not encompassed by the class licence) the operator is no longer authorised to operate under the class licence. In this instance, the operator would be liable for prosecution by the ACMA.

An aeronautical mobile station (and an aircraft station) may only be used for communications that relate to:
  • the safe and expeditious conduct of a flight
  • an emergency
  • a matter that relates to the particular occupation or industry in which the aircraft to which the aircraft station relates is engaged; or the aeronautical mobile station is engaged.
Typically a flight instructor on the ground with a hand-held transceiver supervising a student in the circuit is operating as an aeronautical mobile station. The same might apply to a person advising traffic conditions at a fly-in. The operator of an aeronautical mobile station must use a form of identification that clearly identifies the mobile station.
Equipment standards
Various equipment compliance requirements, specifications and mandatory technical standards apply to radiotelephony equipment intended to equip an aircraft station under the class licence. If it is a fixed installation only Civil Aviation Safety Authority [CASA] approved apparatus may be used; refer to AIP GEN 1.5 para 1.1.

An ACMA approved and licensed hand-held (or demountable) VHF aviation band radiotelephone may be used by pilots of recreational aircraft operating in Class G airspace, provided that the equipment is able to be operated without adversely affecting the safety of the aircraft. Refer to AIP GEN 1.5 para 1.5.

Recreational aircraft operating in Class E airspace must be equipped with a serviceable VHF communications system. The AIP Book is perhaps at variance with the CARs and CAOs so it is not absolutely clear that ACMA approved hand-held units are acceptable in Class E or other controlled airspace.

The standard for hand-held equipment performance is that set out in the Australia/New Zealand Standard 4583:1999 (and later).
Aircraft station identification
All transmitters are required to have an individual identification or call-sign that clearly identifies the station. The call-sign for recreational and sport aircraft registered with CASA is generally the last three characters of the registration marking. The mandatory call-sign for RA-Aus registered aircraft is the aircraft type followed by the four-digit RA-Aus registration number, for example "Thruster zero two eight six".

The call-signs (where 'a' represents an alphabetic character and 'n' a numeric character) for recreational aircraft are:

Recreational aircraft typeCall-sign format
RA-Aus (all groups)(aircraft type)nnnn
Trikes (HGFA registered)TRnnn or TCnnn
Hang GlidersHGnnnn
GyroplanesGnnn and Gnnnn
Sailplanes(VH-) aaa
Balloons(VH-) aaa
General aviation(VH-) aaa

Aeronautical stations
The backbone high frequency [HF] and very high frequency [VHF] civil aviation radiotelephone communications network is owned and operated by Airservices Australia. In addition, regular public transport companies have their own communications networks. Similarly other 'fixed' ground stations could be licensed by ACMA for operation in the aviation VHF band by aero clubs, flying schools and parachute clubs; or by other organisations providing an aerodrome Unicom service. In the regulations such fixed ground stations are called aeronautical stations. However, aero clubs, flying schools and parachute clubs are more likely to operate as 'aeronautical mobile stations'. The military aviation network utilises ultra high frequency [UHF] at military airfields.
Radio frequency symbols
Radio frequencies are described in terms of hertz or 'cycles per second'. The symbols used in the aviation bands are kHz (thousand cycles per second e.g. 2850 kHz) in the HF band and MHz (million cycles per second, e.g. 126.7 MHz) in the VHF and UHF bands.

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1.2 Communication limitations

Communications between aircraft stations; and between aircraft stations, aeronautical stations and aeronautical mobile stations.

A person may operate an aircraft station to communicate with another aircraft station, aeronautical station or aeronautical mobile station only if the communication relates to:
  • the safe and expeditious conduct of flight
  • an emergency
  • a matter that relates to the particular occupation or industry in which the aircraft, to which the aircraft station relates, is engaged
  • proper call-signs must be used.
Communications between aeronautical mobile stations and aircraft stations.

A person who is a member of an aero club, flying school or parachute club may operate an aeronautical mobile station to communicate with an aircraft station for the particular activity only if:
  • the aeronautical mobile station is owned and operated by an aero club, flying school or parachute club; and
  • the communication occurs when the aircraft to which the aircraft mobile station relates is engaged on a flight to or from the aerodrome at which the aeronautical mobile station is located.
Unauthorised communications

From the above, it is evident that an aircraft station may not transmit private or personal messages; i.e. information not pertaining to operational requirements. Nor can an unallocated frequency within the aviation VHF band be used for communications. In addition, all transmissions must be in the English language, use standard phraseology and a phonetic alphabet, and may not include:
  • profane or obscene language
  • deceptive or false information
  • improper use of another call-sign.
Secrecy of communications

CL2006 holders are legally bound not to divulge, without authority, the content of any radiotelephony message sent or received.

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1.3 Aircraft station operating frequencies

Airservices Australia is nominated by the ACMA to approve all frequency assignments made in the aviation bands. Radiocommunications with Airservices Australia's air traffic services [ATS] are chiefly conducted in the aviation VHF communications [COM or COMMS] band, 117.975 to 136.975 MHz where, at 0.025 MHz (25 kHz) steps, there are 760 channels possible. Currently, channel separation in the Australian aviation band, except in Class A airspace, is generally at 0.1 MHz (100 kHz) or 0.05 MHz (50 kHz) spacing. However 25 kHz channel frequencies may be allocated for Class C, D and E airspace, along with rules for frequency stability standards to reduce inter-channel interference. (If a current receiver/transmitter displays frequencies with three decimal places it is likely to meet stability standards; for more information read 'Channel squeeze update' in the May – June 2009 issue of Flight Safety Australia.)

There is a dedicated aviation VHF band from 108.1 to 117.975 MHz for operation of navigation facilities, such as VOR systems. This is the 'NAV band' while the full aviation VHF band from 108.00 to 136.975 MHz is the 'NAV/COM band'.

Some specific aviation operational frequencies are:
  • Aero club operations — 119.1 MHz
  • Flying school operations — 119.1 MHz
  • Fire spotting — 119.1 MHz
  • Parachute club operations — 119.2 MHz
  • Aviation sport — 120.85 MHz
  • Emergency location — 121.5 MHz (plus 243.0 and 406.025 in the UHF band)
  • Glider/sailplane operation — 122.5, 122.7, 122.9 MHz
  • Fishing or agricultural operations or stock mustering — 122.8 MHz
  • Pilot-to-pilot communications — 123.45 MHz
  • Traffic information aircraft broadcasts — 126.35 MHz
  • Aircraft industry testing — 129.1 MHz
  • Crop dusting — 129.6 MHz
  • Aerodrome operator, including refueller — 129.9 MHz
  • Air show — 127.9 MHz
  • Charter and other purposes not listed — 126.4, 128.9, 135.55 MHz
  • Search and rescue only — 121.5, 123.1, 123.2 MHz (plus the 156.3, 156.8 MHz marine band frequencies)
Inter-pilot air-to-air communication frequencies at airfields

Within Class G airspace are some areas, surrounding all reasonably active airfields where, to maintain safe separation, pilots are required to exercise particular monitoring and reporting procedures between each other; and to self-administer movement priorities where appropriate.

These are common traffic advisory frequency [CTAF] areas, and the VHF frequency to be used at particular CTAFs is specified in ERSA and VNC, VTC, PCA and ERC-L charts. Some CTAF airfields may have a private ground-based 'Unicom' information service, the operating frequency of which is the same as the airfield VHF frequency specified in ERSA.

For further information on operations at, or in the vicinity of, airfields in Class G airspace see Radiotelephony communications and procedures in Class G airspace.

Inter-pilot air-to-air communication frequencies en route

Interpilot air-to-air communications can be conducted on frequency 123.45 MHz.

When aircraft are operating in remote areas out of range of VHF ground stations, then 123.45 MHz is the regional air-to-air channel.

Communications between aircraft on 123.45 MHz are restricted to the exchange of information relating to aircraft operations and only the proper call-signs may be used.

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1.4 Radio operator qualification

Operators of aircraft stations must be qualified in accordance with the requirements of the CL2006, which states:

A person may operate an aircraft station or an aeronautical mobile station only if the person is qualified to operate the station in accordance with the Civil Aviation Regulations and the relevant Civil Aviation Orders.

The Chief Flying Instructor of an approved flight training facility may recommend issue of the radio operator's endorsement after evaluation of the applicant's demonstrated performance during flight operations and in an oral or written examination. The examination will cover the syllabus listed in the RAAOs manuals. For example see the RA-Aus Operations Manual section 3.08.

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Groundschool – VHF Radiocommunications Guide

| Guide content | Abbreviations and acronyms |

| [1. Transmitter licensing] | 2. R/T phrasing | 3. VHF characteristics and radio operation |

| 4. Microair 760 transceiver | 5. R/T procedures | 6. Safety and emergency procedures |

| 7. Aviation Distress Beacons | 8. Understanding SAR services |

Next – radiotelephony phrasing The next section of the VHF radiocommunications guide outlines radiotelephony phrasing — aviation English

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