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Airband VHF listening 135.585 Northern high level freq.

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Airband VHF listening 135.585 Northern high level freq.

Old 15th Aug 2019, 22:42
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Airband VHF listening 135.585 Northern high level freq.

Been a life long airband listener...with a break of a few years...been listening to the Northwest high-level freq of 135.585.

A few odd things I don't understand about this freq.

With the aid of Flight Radar I hear transatlantic flights log onto the freq near the midlands but once they seem to reach the cruise altitude I hear nothing else from the aircraft or the ground controllers calling these aircraft...don't ever hear them giving instructions to change to the next sector freq.

I listened to 2 Fed Ex flights come onto this freq 135.585 as they approached the Midland around 70 miles from each other route southeast of Manchester and coast out near Southport just North of Liverpool but bar the first few communications when coming on the freq I hear no more...not ever an interaction to change to the next en-route freq.

What should this be...my antenna is a roof-mounted dipole and I live on high ground with a good horizon...I can hear high flying aircraft over 150miles plus away on my radio so they are not out of range...?

Also is 135.585 a freq that is re-broadcasted...doesn't sound like a direct transmission from the aircraft....bit tinny sounding.

Last edited by magpienja; 16th Aug 2019 at 08:13.
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Old 15th Aug 2019, 23:25
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Originally Posted by magpienja View Post
Been a life long airband listener...with a break of a few years...been listening to the Northwest high-level freq of 135.585.

A few odd things I don't understand about this freq.

With the aid of Flight Radar I hear transatlantic flights log onto the freq near the midlands but once they seem to reach the cruise altitude I hear nothing else from the aircraft or the ground controllers...don't ever hear them giving instructions to change to the next sector freq.

I listened to 2 Fed Ex flights come onto this freq 135.585 as they approached the Midland around 70 miles from each other route southeast of Manchester and coast out near Southport just North of Liverpool but bar the first few communications when coming on the freq I hear no more...not ever an interaction to change to the next en-route freq.

What should this be...my antenna is a roof-mounted dipole and I live on high ground with a good horizon...I can hear high flying aircraft over 150miles plus away on my radio so the are not out of range...?

Also is 135.585 a freq that is re-broadcasted...doesn't sound like a direct transmission from the aircraft....bit tinny sounding.
Airways frequencies are often transmitted from more than one site, each site transmitting slightly 'off' the main frequency so as not to interfere with the other and with 8.33 kHz spacing that means it is transmitted on a very narrow frequency band hence the tinny sound.
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Old 16th Aug 2019, 05:25
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CPDLC?

https://www.skybrary.aero/index.php/...ations_(CPDLC)
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Old 16th Aug 2019, 06:46
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You say you use a dipole - vertically mounted I trust? If it is horizontal it would havew directional properties.
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Old 16th Aug 2019, 08:07
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Hi HD...yes vertically polarized so Omnidirectionally.

Its crossed my mind that once at cruise alt the North America bound aircraft communicate via there data link....odd that they dont report QSY the freq.
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Old 16th Aug 2019, 08:09
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Sorry Squawk 6042...I had not read your link when I posted my last.
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Old 16th Aug 2019, 12:00
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Originally Posted by magpienja View Post
Hi HD...yes vertically polarized so Omnidirectionally.

Its crossed my mind that once at cruise alt the North America bound aircraft communicate via there data link....odd that they dont report QSY the freq.
Squawk 6042 may well have it - If flights are operating CPDLC then you won't hear a voice "QSY" (I'm not a radio amateur but I believe that means a read back of frequency going to? as in "contact Shannon on ...")..

How it works with CPDLC on board is that the new frequency gets sent up to the aircraft by datalink, the crew do a datalink acknowledgement of that change and then they switch frequency, no voice call on the old frequency, onto the new VHF freq.

Once you get to the new frequency you still check in by voice, and then if still CPDLC you may well go silent again ( as far as VHF voice is concerned)...

All the above may well explain why you are only hearing traffic on the initial call as they enter the sector you are listening to.
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Old 16th Aug 2019, 13:13
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All sounds about right Wiggy.

Only seems as far as I can see applies to a/c that is going to route across the Atlantic.

Yes your quite right QSY= change freq.

I am also a keen HF radio airband listener...but not as much to listen to these days with the advent of the data link...but they do still check-in.
Seems data link is not always a reliable link via data as I often hear the controller call an aircraft out over the ocean to say you link has failed...so old school technology still works when modern doesn't.
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Old 16th Aug 2019, 16:59
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Originally Posted by magpienja View Post
All sounds about right Wiggy.

Only seems as far as I can see applies to a/c that is going to route across the Atlantic.
That might be because it's (possibly) more likely a Long Haul type will have CPDLC and have it logged on whilst overflying domestic airspace, vs a short haul flight doing a short domestic sector where CPDLC might actually complicate matters.

If you could monitor ATC elsewhere in the world you'd hear a similar "silent change" process pretty much anywhere when leave a CPDLC sector or change from one CPDLC sector to another, e.g; when crossing the boundary between say Gander and Moncton, or closer to home switching sectors in Maastricht airspace...



And yes, sometimes the gremlins creep in and you either have to re-log on or revert "to voice".

Last edited by wiggy; 16th Aug 2019 at 17:20.
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Old 16th Aug 2019, 17:09
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I see....very informative thank you.
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