Pairing up the tower freqs VHF/UHF

[737mech]

Is there a proven way or formula to figure out why an airport using both VHF and UHF freqs for the tower freqs? Is there a reason or method? Say a Military base is using VHF xxx.xxxx and UHF xxx.xxxx ok, well sometimes when monitoring you can catch the tower better on UHF and the Planes on VHF? Most of the published airports have both VHF and UHF freqs listed for the tower and approach/departure etc. They seem very random and without methodology to pair the freqs? Who decides what freqs are assigned to an airport? This would be good info if you thought you were only getting half the conversation.

[DaveNF2G]

VHF frequencies are for civilian aircraft (and some military). UHF frequencies are exclusively for military use.

There is no fixed relationship between VHF and UHF frequencies at any facility. The FCC licenses VHF, and NTIA allocates UHF.

[HenryDavid]

Not sure about these days, but it used to be that US Navy aircraft had only UHF capability.

Most civilian towers have UHF capability, but the frequency is published only in the FLIP/DOD publications and not on civilian charts.

A phone call to your local tower should help discover the frequency.

[zz0468]

Originally Posted by HenryDavid

Most civilian towers have UHF capability, but the frequency is published only in the FLIP/DOD publications and not on civilian charts.

I have sectional, WAC, and terminal charts that list both VHF and UHF frequencies on them.

[DPD1]

If you're asking if there's a predictable formula to matching the two, like some ham repeaters and other systems have... then no. They decide who talks where based on a lot of factors, but there's no predictable split between the bands on air.

Dave
www.DPDProductions.com
Antennas & Accessories for the RF Professional & Radio Hobbyist

[HenryDavid]

zz0

Good show! The older charts did not display the UHF frequencies.

[KE5CCA]

Originally Posted by DaveNF2G

The FCC licenses VHF, and NTIA allocates UHF.

I do not know if that is entirely true. According to the "Facility Transmitting Authorization" hanging on the wall here, it says:

In accordance with authority granted the Federal Aviation Administration by the National Telecommunications & Information Administration through the Interdepartmental Radio Advisory Committee, this Authorization is issued for the operation of this facility.

Since there are VHF and UHF frequencies listed, it would seem that the FAA, through Spectrum Management, is responsible for assignments in both bands.

[DaveNF2G]

How old is that notice? I'm not sure that IRAC exists any more.

[nd5y]

It does.
http://www.ntia.doc.gov/osmhome/irac.html

[Lynch_Christopher]

On the NTIA website where does it say what frequencies are allocated to each facility.

[DaveNF2G]

It doesn't. Federal frequency allocations have been Classified since 1982.

[Lynch_Christopher]

So even the air traffic control frequencies allocations are classified?

[DaveNF2G]

ATC on VHF and possibly UHF are public record as long as they are licensed through the FCC.

IRAC allocations were classified by President Reagan's Executive Order in 1982.

[K4DHR]

Originally Posted by HenryDavid

Not sure about these days, but it used to be that US Navy aircraft had only UHF capability.

Most civilian towers have UHF capability, but the frequency is published only in the FLIP/DOD publications and not on civilian charts.

A phone call to your local tower should help discover the frequency.

Approach plates have the UHF frequencies listed where they exist.

http://204.108.4.16/d-tpp/0811/00026I10C3.PDF

Note that there's only one UHF frequency in use for both local control and ground control. Radar facilities will have a UHF pairing for every sector in use. Low altitude en-route charts will have both VHF/UHF frequencies listed.

A tower at a smaller airport isn't likely to have UHF radios in place unless it sees some military traffic periodically.

[Big_Ears]

Or maybe the question is: Which tower VHF frequency is simucasted to which tower UHF frequency?

[unitcharlie]

airnav.com lists UHF freqs for airports with military traffic in Kentucky....

[K4DHR]

Originally Posted by Big_Ears

Or maybe the question is: Which tower VHF frequency is simucasted to which tower UHF frequency?

It depends on which controller is working the airplane. Each position has the ability to select several frequencies (including other positions) from a panel, which may be either physical switches in older facilities or a touch screen in ones that have had some or all of their equipment updated in the past 8-10 years.

For a facility like Atlanta that has little military traffic (they'd only do it in an emergency most likely, Dobbins ARB is about 15 miles NW) the tower or ground position would probably get a heads up over the shout-line from the approach control letting them know that the aircraft they're about to get is UHF only.

[DaveNF2G]

They should not need a "heads up" to hear an emergency (or any other) call. Any facility that lists an operating frequency should be monitoring that frequency.

[K4DHR]

Originally Posted by DaveNF2G

They should not need a "heads up" to hear an emergency (or any other) call. Any facility that lists an operating frequency should be monitoring that frequency.

Not necessarily. At towers within class B/C airspace may not monitor anything but 243.0 because of interference over the UHF radios. I had the supervisor at one of the nearby ATC facilities tell me that they try to work what military traffic they do get on VHF if at all possible.

[coldbricks]

any time that frequency is keyed up alarms would go off. Its very similar to transponder codes that trigger alarms.