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British area controllers / London Control and 121.5MHz

I wondered if British area controllers listen to / have a switch to emit on 121.5 MHz or whether that is “reserved” for the actual search & rescue guys (I believe that is the Royal Air Force Distress and Diversion units) in the UK, or if they somehow have other restrictions (low power emitters?) on their capacity to use the guard channel? I “often” hear Langen Radar call up airliners that they’ve lost contact with on 121.5, and occasionally I also hear French ATC do that. But yesterday, I left the coverage area of one of London Control’s frequencies, and they resorted to relaying the request to switch to the new frequency to me via a Speedbird (British Airways) plane. Anybody know why they had to go such an indirect route?

ELLX

UK ATC for Class A and Class D don’t listen or talk on 121.5, this is delegated to RAF(U) D&D who handle it, D&D sits within NATS Swanwick so coordination is easy

I did call 121.5 on ground at Southend by mistake, I think some airliner with Spanish accent called back to tell me I am on the wrong frequency just as I was about to switch to Ground frequency

RAF cover for 121.5 is down to 1000ft agl with VHF-style direction finding

No idea if ATC can transmit but I imagine for airliners on lost com they would get RAF to do it?

Last Edited by Ibra at 07 Nov 12:19
Paris/Essex, United Kingdom

“RAF cover for 121.5 is down to 1000ft agl with VHF-style direction finding.”
I think only in the South. I’ve seen a cover map somewhere.

Maoraigh
EGPE, United Kingdom

But yesterday, I left the coverage area of one of London Control’s frequencies, and they resorted to relaying the request to switch to the new frequency to me via a Speedbird (British Airways) plane. Anybody know why they had to go such an indirect route?

Because the Speedbird was close and ATC found it will be the easiest and best solution that way.

Smooth
LOXX, Austria

I think only in the South. I’ve seen a cover map somewhere.

Maybe, also I heard they are cutting back on some nationwide VHF transmitters & receivers, so they can’t triangulate easily…

Last Edited by Ibra at 07 Nov 19:56
Paris/Essex, United Kingdom

It’s not very clear; the blue line is the coast with the red circle over London. The original is on this pdf from the CAA, and a bit more info from the RAF at Swanwick. Scotland, Northern Ireland and Cornwall are obviously expendable

Edited to add: the second pdf has a list of direction finding stations, but it’s from 2017 so may not be current

Last Edited by Capitaine at 08 Nov 10:34
EGHO-LFQF-KCLW, United Kingdom

Thanks for the reference my guess that refers to AMSL not AGL? and it is for VHF triangulation not raw radio TX/RX coverage?

My understanding anyone flying bellow 3000ft amsl OCAS without ModeS/C is not worth saving, they already sold their lives to the devils

Last Edited by Ibra at 08 Nov 11:41
Paris/Essex, United Kingdom

I don’t think there is any connection between

  • London Control (LTCC?) having access to the 121.50 frequency
  • the UK 121.50 VDF (VHF direction finding) facility known as D&D – this was originally set up to support RAF aircraft which got lost (in the pre-GPS age, and with no INS)

I can’t see a tech reason why LTCC cannot listen on 121.5. Presumably it is just a policy; nobody with the time to respond.

The above mentioned 2000ft/3000ft coverage is just D&D, which nowadays gets very little use.

Administrator
Shoreham EGKA, United Kingdom
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