Following an Aeronautical
Information Circular (AIC) earlier published by the South African
Civil Aviation Authority (SACAA) about the need to introduce new
frequencies to meet demand, the SACAA recently announced that as
from March 2011, Cape Town International Airport's Flight
Information Services (FIS) west frequency changes from 126.5 MHz to
131.125 Mhz.
The Manager of Communications,
Navigation and Surveillance at the SACAA, Mr. Koos Pretorius, says:
"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 (African and Indian Ocean region). It is
critical to note that while a change was necessary, this change was
done in compliance with the ICAO AFI plan." He adds that the CAA
understands that there will be teething problems at the beginning.
However, to ensure a safe, orderly and expeditious flow of air
traffic, he says "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."
According to him, 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 usable frequency is simply
dictated by external and most often, non-aeronautical factors,"
says Mr. Pretorius.
Mr. Pretorius further observes 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 warns against
speculations that the aeronautical VHF band is virtually limitless,
with a 'preferred frequency on demand' scenario in place, saying
that "The opposite is in fact true."