Guidance concerning Air Navigation in and above the NAT MNPSA
COMMUNICATIONS AND POSITION REPORTING PROCEDURES
It is important that pilots appreciate that routine air/ground ATS Voice communications in
the NAT Region are conducted via aeradio stations staffed by communicators who have no executive ATC authority. Messages are relayed by the ground station to/from the air traffic controllers in the relevant OAC.
In the North Atlantic Region there are six aeronautical radio stations, one associated with
each of the Oceanic Control Areas. They are: Bodo Radio (Norway, Bodo ACC), Gander Radio (Canada, Gander OACC), Iceland Radio (Iceland, Reykjavik ACC), New York Radio (USA, New York OACC), S a n t a M a r i a R a d i o ( P o r t u g a l , S a n t a M a r i a O A C C ) a n d S h a n w i c k R a d i o ( I r e l a n d , S h a n w i c k O A C C ) However, the aeradio stations and OACs are not necessarily co-located. . For example, in the case of
Shanwick operations, the OAC is located at Prestwick in Scotland whilst the associated aeradio station is at Ballygirreen in the Republic of Ireland. In addition to those six aeronautical stations, there are two other stations that operate NAT frequencies. They are Canarias Radio which serves Canarias ACC and Arctic Radio serving Edmonton, Winnipeg and Montreal ACC’s.
HF Voice Communications
The majority of NAT air/ground voice communications are conducted on SSB HF
frequencies. To support air/ground ATC communications in the North Atlantic Region, twenty-four HF
frequencies have been allocated, in bands ranging from 2.8 to 18 MHz.
There are a number of factors which affect the optimum frequency for communications over
a specific path. The most significant is the diurnal variation in intensity of the ionisation of the refractive layers of the ionosphere. Hence frequencies from the lower HF bands tend to be used for communications
during night-time and those from the higher bands during day-time.
Generally in the North Atlantic
frequencies of less than 7 MHz are utilised at night and frequencies of greater than 8 MHz during the day.
The 24 NAT frequencies are organized into six groups known as Families. The families are
identified as NAT Family A, B, C, D, E and F. Each Family contains a range of frequencies from each of the HF frequency bands. A number of stations share families of frequencies and co-operate as a network to provide the required geographical and time of day coverage.. A full listing of the frequency hours of operation of each NAT aeradio station is contained in the “HF Management Guidance Material for the NAT Region” – ICAO NAT Doc 003 (Appendices C- 1 thru 6), available via the ICAO EUR/NAT website at www.paris.icao.int/ . Each Family is designated for use by aircraft of specific States of Registry and according to the route to be flown. NAT ATS provider State AIPs list the families of frequencies to be used.
Each individual aircraft is normally allocated a primary and a secondary HF frequency,
either when it receives its clearance or by domestic controllers shortly before the oceanic boundary.
When initiating contact with an aeradio station the pilot should state the HF frequency in HF Radio operators usually maintain a listening watch on more than one single frequency.
Identification by the calling pilot of the particular frequency being used is helpful to the radio operator.
NAT Doc 007