SACAA announces new Cape frequency

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The South African Civil Aviation Authority (SACAA) says the new frequency for Cape Town International Airport’s Flight Information Services (FIS) is 131.125 MHz. The frequency changed from 126.5 MHz yesterday, the authority says in a statement.

This change in frequency follows the publishing, by the SACAA, of an Aeronautical Information Circular (AIC) a few years ago about the need to introduce new frequencies to meet demand. “Contrary to circulating reports that this change is sudden, Cape Town’s frequency change follows an announcement that was made in January 2002, says Koos Pretorius, Manager of Communications, Navigation and Surveillance at the SACAA. “Back then we wanted the aviation community to have adequate time to prepare for envisaged changes such as this one. It was clear from back then that air traffic movements and services within the country and adjacent territories were continually increasing and the need for Very High Frequency (VHF) communication channels was also on the rise.
“The situation was, and still is, aggravated by the higher operating altitudes of modern aircraft as a result of which the minimum distance between ground station operating on the same VHF channel must be increased if air-to-air interference is to be avoided,” added Pretorius.

Pretorius continues that over time it became virtually impossible to allocate frequencies for all services and at the same time accommodate the limited frequency coverage of certain aircraft. He further cautioned against the belief that the aeronautical VHF band is virtually limitless, with a “preferred frequency on demand” scenario in place. “The opposite is in fact true,” said Pretorius.
“South Africa changed to the 25 KHz channel spacing in 1986 because of an aeronautical band that was becoming more and more cluttered. In simple terms, more channels had to be found. South Africa might have been the first African country to go this route, but it should be noted that all of Africa is today on 25 KHz channel spacing in the aeronautical VHF band. Globally this is also the case, although certain high and upper level services in Europe already had to go one step further by introducing the 8.33 kHz channel spacing,” Pretorius elaborated.

The available aeronautical VHF band is controlled by an International Civil Aviation Organisation (ICAO) regional band plan for Africa and the Indian Ocean region and is referred to as the AFI plan. The AFI plan sub-divides the band between 118.000 MHz and 136.975 MHz into many allotments, each with a dedicated purpose. That means that a small sub-band is set aside, for example for surface movement control, whilst another is for approach, information, and so forth.

Complicating this further is that the longer range services, such as approach and area are further split into levels such as lower, intermediate and upper; each with its own sub-band with dedicated frequencies. The gaps in the AFI band plan are used for national allocations and from here small aerodromes, flying clubs, aerodrome services such as fueling, catering; and other services that are not published such as company operations get their assigned frequencies.



The SACAA further points out that this frequency change was done for technical reasons. “Where a large number of operational frequencies are concentrated on a major airport, such as Cape Town, the simultaneous use of two frequencies causes a resultant third frequency which will interfere if that third frequency is in use. Another issue is the limitations caused where multiple frequencies use a common antenna. This has seriously limited the choice of suitable frequencies from those that were available to AFI. It is critical to note that while a change was necessary, this change was done in compliance with the ICAO AFI plan,” Pretorius elaborated.
“We understand that there will be teething problems at the beginning, however, to ensure a safe, orderly and expeditious flow of air traffic there appears to be no alternative to making it mandatory for all aircraft operating in a given controlled or advisory airspace to be equipped with radio communication equipment capable of transmitting and receiving on all of the VHF channels allocated to such airspace. In view of this fact, aircraft operating in South African airspace must be equipped with VHF radio communication equipment capable of operating on any 25 kHz channel in the band 118,000 MHz to 136,975 MHz. This requirement was made effective from as far back as January 2005. We thus expect most aircraft to be compliant at this point. While every effort is made to assign frequencies of one or two decimal places to accommodate especially the older aircraft, in many cases the useable frequency is simply dictated by external and most often, non-aeronautical factors,” concluded Pretorius.