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.
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 |
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):
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
Identifier | Data Encoding Rule | Justification | Data Verification Rule (UID) | Remarks |
---|---|---|---|---|
RCC-201 | Each RadioCommunicationChannel shall have assigned frequencyTransmission value | AIXM 4.5 / Minimal data rule | AIXM-5.1_RULE-1A3376 | |
RCC-101 | RadioCommunicationChannel.frequencyTransmission and RadioCommunicationChannel.frequencyReception shall be encoded in case of two-way radio communication is provided. | Data harmonisation | TBD | |
RCC-102 | If a Service has more more than one frequency (radioCommunication), specify its usage (e.g. by rank or other purpose distinction such as flight levels). | Data consistency | TBD |
Coding Examples
See topics ATS Unit providing Service, Controlling Unit for Route Segment, and Controlling Unit for En-route Holding.