G'day Mr Tr,
Re; As traffic increased more FS freqs were introduced.....Post #85....
Not only 'as traffic increased', but with the introduction of the 'Jets', as the percentage of 'high flying' traffic increased, and the calls on 122.1 from the FK.28 in one area (For example...) at FL280 were 'superimposed' onto the adjoining area(s) by virtue of the transmitting aircraft's altitude, then it soon became obvious that a 'separation' of frequencies was required.....
Hence the various differing frequency 'numbers' ...around 'the adjoining traps'.....(F.I.A.'s)....
Cheers
