AIR/GROUND COMMUNICATIONS

Communications with aircraft transiting the North Atlantic are an important part of Isavia’s international air services. The service area consists primarily of the Reykjavik Air Traffic Control Area. Our services ensure effective and secure communications between aircraft, area control centres, aircraft operators, meteorological offices and other parties involved in air traffic.

Our Communications Centre at Gufunes maintains voice communications on HF and VHF frequencies in close co-operation with the Ballygirreen Radio Station in Ireland. The communications are conducted in English and mainly involve the receipt and transmission of messages relating to aviation safety, such as position fixing, various changes in altitude, speed or route, weather messages, information on landing conditions at airports, etc. Messages from aircraft are transmitted, as the case may be, to area control centres, meteorological offices and aircraft operators.

Air/ground communications staff came under considerable pressure during the Eyjafjallajökull eruption in 2010. The average number of messages processed per 24 hours that year was 1,329, but during the four busiest air traffic days in the Icelandic control area, the average daily number was 4,609.

In very broad terms, the Gufunes Communications Centre’s activities can be divided into two main categories: (1) radio communications with aircraft in flight (Aeronautical Mobile Service or AMS) and (2) the operation of an AFTN/CIDIN message switch (Aeronautical Fixed Service or AFS). The AFTN/CIDIN switch forms part of the international aviation-related message distribution system. The switch at Gufunes is connected to comparable switches in London, Norway, Canada and Greenland. In Iceland, it is connected to the Area Control Centre, Keflavik Airport and various aircraft operators’ facilities. Operational management of the system is in the hands of a watch officer at Gufunes, with technical support provided by the Air Navigation Services division.

The part of the Communications Centre that handles air/ground communications is far more extensive and requires more manpower. In oceanic air traffic control, the communications centres handle radio communications with pilots, except when the aircraft is under radar control. The radio operator receives messages from the controller and forwards them to the aircraft in question and vice versa.

The most common services are the following:

• Position reports from aircraft at cleared reporting points
• Pilot requests for changes in altitude, speed or route
• Air traffic control clearances from the Area Control Centre
• Weather information to and from pilots
• Information provided to Airline Operations Centres (AOCs)

The Gufunes Communications Centre provides a 24-hour service on HF and VHF GP frequencies. It has a total of eight working positions to handle air/ground communications.The HF service is provided in three frequency groups:

Pilots generally prefer to communicate on VHF frequencies rather than HF because listening conditions on VHF are far superior. However, the transmission range of VHF is only a fraction of that of HF and is limited to little more than line of sight. This makes it important to position the equipment as high up as possible to increase range. VHF connections commonly have a range of some 250 nautical miles. Iceland’s geographical position provides a certain uniqueness, since by installing VHF equipment in Iceland, the Faroe Islands and Greenland, the Gufunes Communications Centre can offer a continuous VHF service area over the North Atlantic. VHF GP service is provided at three frequencies: 126.55 MHz, 127.85 MHz and 129.75 MHz. In Iceland, VHF equipment is located at Mt Gagnheiði, Mt Háfell, Mt Háöxl, Mt Þorbjörn and Mt Þverfjall. In the Faroe Islands, the equipment is located on the island of Fugloy, and in Greenland it is located at the Dye One and Dye Four stations. HF transmitter equipment is located in the town of Grindavík and at Bessastaðir in the West Húnaþing region, with receivers located at Þverholt in Borgarfjörður, at Garðskagaviti and on the west coast of Norway. There is also one transmitter and receiver in Söndreström on Greenland’s west coast. Each year, approximately 500,000 messages are dispatched from the Centre, of which 65% are on VHF frequencies.

Another area of activity for the Gufunes Communications Centre is data communications with aircraft. In collaboration with the American communications company ARINC, equipment for data communications with aircraft on both HF and VHF frequencies is operated from Gufunes. At Grindavík, there are HF transmitters for this use, with a receiver located at Þverholt. Equipment for data communications at VHF frequencies is located on Mt Háfell and Mt Þorbjörn in Iceland, on Mt Spáafell in the Faroe Islands, and at three locations in Greenland: DYE One, DYE Four and TOP775. These locations provide a continuous service area over the North Atlantic on VHF frequencies. Outside this area, HF services are provided. The volume of data communications with aircraft continues to grow, both in the form of data received by airlines from their aircraft and because communications between aircraft and area control centres are increasingly shifting to data links.

Clearly, the share of traditional voice radio links with aircraft will decrease in the coming years. Such services are currently provided from six stations located in Ireland, Canada, the United States, Portugal and Norway, in addition to Iceland. The number of these stations is certain to fall progressively over the coming years. Currently, approximately 50% of the traffic transiting the Reykjavik control area uses data-link communications. However, the increase in traffic using data links will be partly offset by the overall increase in air traffic forecast for the coming years. Within Isavia, preparations have long been underway for these changes.

The stations at Gufunes and Ballygirreen in Ireland are integrated and operate as a single unit. The Ballygirreen Radio Station provides communications services in the British/Irish-managed Shanwick Oceanic Control Area south of the Icelandic area. Instead of dividing the traffic between the stations at the edges of the respective control areas, it is divided so as to minimise the traffic peaks at each station. This provides an enhanced combined service at lower operating costs. At the same time, the stations serve as alternative stations for each other, which reduces capital and running costs by eliminating the need to build a new alternative station.

Approximately 40 flight information officers, divided into 5 shift teams, work in the Communications Centre.