LTCSZ,
would like to try my hand at monitoring some of the high altitude aviation frequencies as planes fly over my area
I've attached a chart below that shows the ARTCC high altitude sector boundaries and frequencies centered around Garden City, KS. This is something I put together myself from various references and was up to date as of around 12 months ago.
Some notes on the chart ....
For reference there is a 200 nautical mile range ring (in red) centered on Garden City (GCK).
ZKC22, 133.450, 370B would be decoded as follows ....
Kansas City ARTCC (ZKC) Sector 22, frequency 133.450, altitude FL370 and below
To make things more complicated they can use different sector configurations depending on the time of day and traffic volume. I've tried to show this on the chart.
An asterisk (*) beside the frequency indicates it is a secondary frequency used when required. For example ZKC20, 134.30, is used when required otherwise the sector is combined with the adjacent sector ZKC06 and 133.200 is used.
An asterisk in a circle on a sector boundary indicates the sectors are combined as required. For example ZKC21 and ZKC07, both extending from FL380 and above, are combined when traffic is light, when they are combined 120.725 is the frequency used.
The floor of high altitude airspace in the USA generally starts at 24,000 feet (FL240). There are exceptions though, in ZDV (Denver) the floor is FL270 and ZAB (Albuquerque) the floor on some sectors is FL290. If the floor is not at FL240 then the actually altitude is shown on the chart. For example ZDV28, Denver Sector 28, 134.125, extends from FL270 to FL330. All Kansas City high sectors start at FL240.
You should be able to hear the Kansas City controller on 133.450 (high altitude) and 125.200 (low altitude).
The low altitude sector, ZKC68, that you can hear the controller on 125.20 is quite large, in addition to 125.20 they use 5 other frequencies for coverage in this sector. In case you wondering why you are not hearing the aircraft, the other frequencies used in this sector are 118.80, 124.40, 134.00, 118.35, 126.95.
The easiest way to confirm frequencies and sector configuration is to follow flights and note the frequency they are handed off to.
If you happen to note any frequencies or configurations that are different then what I have depicted on the chart can you please let me know so I can update it. I'd be happy to answer any more questions if you have any.
AS