UHF RCAG monitoring

[rayvelcoro]

I don't do a lot of aviation scanning, but I've lately become interested in UHF RCAG's. From Atlanta, I listen to 317.700 in ZTL sector. I use a BC 125 indoors w/ portable antenna. Does anyone know why this frequency would be active on some days and then go for a week or two with nothing? Is it related to atmospheric conditions or is the transmitter only active part-time? I've noticed similar behavior on another frequency.

 

[ATCTech]

Unless there's military traffic transiting the sector there's no requirement for ATC to keep it selected for TX. The RX would be live at the sector however.

 

[KO4RJX]

Depending on how close you are to the site you could be hearing the controller side of the conversation, they are simulcasted with the VHF traffic nearly full time around our area (Washington Center). However as ATCTech stated unless you have military traffic in the area your likely to not hear anything. The only military traffic on the UHF sites I monitor are fighter jets and bombers, such as Seymour Johnson F15's, Navy F18's, the occasional F-16 up from Shaw AFB and a few times a year we get B-52's flying over. Your bigger military aircraft, C17's, 130's, C5's, E6's etc use the VHF side.

 

[AirScan]

According to the RR database 317.700 is listed as a "Workload" frequency used in Sectors 1/2/3/4/5/6/39 (I think the 39 is a typo and should be 38 ?). These are sectors to the west through north of Atlanta. It's paired with 135.000. Being a "workload" frequency would explain why it's only used part time as required.

I'm not that familiar with the area so I'm not sure exactly what it would be used for ? Military airspace that is only operational at certain times or maybe just a spare for a regular frequency that is down ? If you hear it in use again, as well as 135.000, can you maybe provide more details, like time in use and flight numbers or call signs heard.

Cheers,

 

[Flyham]

There's a page/group on FaceBook where ATC and Pilots often congregate and a similar question was posed.
The overall response was VHF & UHF often depend on workload and preference from military service. Meaning Airforce mightbe more apt to use VHF, yet Marines & Army would use UHF. Also mentioned that controllers will often keep their respective VHF & UHF selected and will multi cast on both as a means of situational awareness.

 

[alcahuete]

There's a page/group on FaceBook where ATC and Pilots often congregate and a similar question was posed.
The overall response was VHF & UHF often depend on workload and preference from military service. Meaning Airforce mightbe more apt to use VHF, yet Marines & Army would use UHF. Also mentioned that controllers will often keep their respective VHF & UHF selected and will multi cast on both as a means of situational awareness.

It is really not dependant on the branch of service. It's dependant on the aircraft type. Most fighters, outside of the F22, F35 and upgraded F18s and such, do not have VHF capabilities. They are generally UHF only. Tankers, Cargo, and helicopters are normally VHF, though most have UHF capabilities as well. They almost never use UHF when dealing with civilian ATC, however.

As far as "multicasting" it is normally covered in the facility FSOPs that the transmitter on both VHF and UHF be turned on, where both are available. I personally do not know of any facility where it is not a requirement. The only exception is the UHF "tactical" frequency, in which the transmitter may be turned on as needed.

I don't do a lot of aviation scanning, but I've lately become interested in UHF RCAG's. From Atlanta, I listen to 317.700 in ZTL sector. I use a BC 125 indoors w/ portable antenna. Does anyone know why this frequency would be active on some days and then go for a week or two with nothing? Is it related to atmospheric conditions or is the transmitter only active part-time? I've noticed similar behavior on another frequency.

If there are no UHF-equipped (generally fighters) aircraft on the frequency, it isn't going to be in use on the receive side. Chances are you aren't going to hear much at the weekends, at night, etc.