Radio Communication Channel [RCC]

AIXM Model Overview

AIXM 5 defines the class RadioCommunicationChannel as follows:

A radio frequency band of sufficient width and associated identification data used for one- or two-way communication from or to a transmitter on the ground or in the air.

Basically, a RadioCommunicationChannel is used by a Service or a NavaidEquipment.

The main attributes of the RadioCommunicationChannel are the frequency or channel or logon address on which the Service or the Navaid is transmitting and can be received.

for one way broadcast (e.g. ATIS); frequencyTransmission is coded
for two-way radio communication on the same frequency (single channel simplex); both frequencyTransmission and frequencyReception contain the same value
for two-way radio communication on two distinct frequencies (double channel simplex, offset frequency simplex, duplex); frequencyTransmissioncontains the transmission frequency and frequencyReception contains the reception frequency (as seen by the service provider).

The RadioCommunicationChannel.rank attribute can be used indicating the role of the communication channel, in terms of primary, alternate, emergency, etc.

The RadioCommunicationChannel may have also an associated schedule, which indicates the usage time of that particular communication frequency or channel.

Coding guidelines

VHF communication (25 KHZ versus 8.33 KHZ spacing)

As explained in the Eurocontrol "8.33kHz Voice Channel Spacing (VCS) Implementation Handbook", edition 1.1, July 2017: "The introduction of 8.33 kHz channel spacing involves the conversion of existing 25 kHz channels to 8.33 kHz channels. An 8.33 kHz channel has a reduced bandwidth compared to its 25 kHz counterpart. This allows for the creation of two adjacent 8.33 kHz channels on the so-called “shoulder” frequencies". The following diagram provides an example:

AIXM allows distinguishing between transmission/reception radio frequencies and radio channels, as explained below:

When 25 KHZ spacing is used, then the frequencyTransmission and the frequencyReception attributes shall be used, both with the same value and including the unit of measurement (MHZ). In addition, the mode attribute shall get the value 'VHF' (which is defined as “Very High Frequency radio voice channel with 25 KHz spacing.”). For example:

mode='VHF'
frequencyTransmission=132.050 MHZ
frequencyReception=132.050 MHZ

When 8.33 KHZ spacing is used, then the channel property shall be used. In addition, the mode attribute shall get the value 'VHF_833' (which is defined as “Very High Frequency radio voice channel with 8.33 KHz spacing.”). For example:

mode='VHF_833'
channel=132.055

Frequency purpose (rank)

The rank attribute should be coded in accordance with the usage not with local terminology. For the usage of the values provided for the rank attribute the following rules should be taking into account:

CodeFacilityRankingType	Rule
PRIMARY	Use for main/normal frequency
SECONDARY	Use for secondary frequency and also if other terms (stand-by freq, back-up freq, alternate freq) are used in the sense of a secondary frequency AIXM 5.2 Improvements A change proposal (AIXM-542) for the next AIXM 5.2 version has been approved by the AIXM Change Control Board, which deletes 'SECONDARY' from CodeFacilityRankingType list of values utilised by RadioCommunicationChannel.rank and Service.rank (and its subclasses) The coding guidelines provided here are aligned with forward/backward conversion rules contained in the AIXM-542 Change Proposal.
EMERG	Use for emergency frequency, e.g. 121.500 MHZ (Aeronautical emergency frequency), 123.100 MHZ (Auxiliary frequency (SAR))
GUARD	Use if used in the sense of "listening only" frequency, except for emergency frequencies
ALTERNATE	Note Note: Not clear what is the difference between Secondary and Alternate. Has to be raised to AIXM CCB

Annex 10, Volume V, Chapter 4 ,contain a general allotment of the frequency band 117.975 – 137 MHz. The main subdivisions of this band are the frequency bands allocated to both international and national services and frequency bands solely allocated to national services. Specific allotments to services are to be determined regionally. The figure below shows the special frequencies and allotments (Annex 10):

European Regional procedure

Note that in the European Region, EUR Doc 011, EUR FREQUENCY MANAGEMENT MANUAL extends the range of frequencies reserved for data link, starting from 136.500 MHz.

Traffic advisory frequency

At smaller airports, landing sites or in airspace reserved for specific users (such as gliders) it is possible that a "traffic advisory frequency" is provided. This is used by the pilots flying in the area to announce their flying intentions, for the other pilots to be aware of their position and intended trajectory. In some States this is labelled as "Common traffic advisory frequency". In AIXM, this can be coded using a RadioCommunicationChannel associated with a AirTrafficControlService with type equal-to 'CTAF'. It is not necessary to associate it with a specific Unit, unless there actually exists an ATS Unit that provides some level of air traffic separation service using the same frequency.

Frequency in airspace

In AIXM a frequency cannot directly be assigned to an Airspace. The frequency is related to a Service. The Service then is provided within one or more client Airspace. If the radio frequency of a service is in use for certain levels or within a specific geograohical area, this can be coded using the RadioFrequencyArea and eventually sector.CircleSector child elements. See also topic ATS Unit providing Service.

Coding Rules for Radio Communication Channel

Unable to render {include} The included page could not be found.

Coding Examples

See topics ATS Unit providing Service, Controlling Unit for Route Segment, and Controlling Unit for En-route Holding.

(ICAO) AIP Data Set