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Freq readback 6 digits

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Old 9th Aug 2007, 14:51
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Freq readback 6 digits

After a couple of years of 8.33 frequencies around and almost two years of all frequencies being spoken as 6 digits in theory (with the exception of full 100 kHz) my impression is that there is still much freq load produced by this subject.
Yesterday a non representative count in a high traffic situation (upper airspace sector) showed around 20-30% of all readbacks being either false or the flight deck asking for the freq a second time (some a third time).
Is there anything that can be done about this?
I know, the ground station discipline to use 6 digits is still rather low. Is this a contributing factor? Would omitting the leading "1" (UHF could be preceeded by a "UHF") help?
Thank you
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Old 9th Aug 2007, 21:50
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6 Digit Readback

It probably depends on how important an individual controller sees using 6 digits as per the ATSIN and recent instructions. If each of us were to perhaps be more stringent in obtaining a correct readback when a pilot doesn't give full readback may'be word would get round!!!
This is not of course the easiest thing to do on a busy sector when it is probably perfectly olbvious the pilot is going to the correct frequency anyway !
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Old 10th Aug 2007, 05:43
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This is a Yank rant...

rant on

Why the hell do we need 8.33 spacing in the first place? Is it a Euro conspiracy to sell new radios? If we can manage the busiest airspace in the world without 'em, why not Eurocontrol?

rant off

Yes, I know the arguments about many small countries, many ATC service providers, yada, yada, but all of Europe could be covered by the Eastern US.
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Old 10th Aug 2007, 06:40
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galaxy flyer... I've read two of your rants this morning. You really ought to calm down, my son, or you'll be a candidate for a heart attack!
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Old 10th Aug 2007, 06:57
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Use of 6 digit instructions & readbacks is an ICAO recommendation adopted by Eurocontrol. Believe me, the UK Phraseology Working Group looked at ways to avoid it, but to put it plain and simple, if a particular country has just one 8.33 khz frequency, it's required to comply; the fact that the USA does not notify any 8.33 khz is why you do not have to comply in the US. Why 8.33 and not 12.5 khz (which would have been the 'natural' next stage)? Who knows, but the French uptake of these channels might give you a clue.
There was also some evidence that with some 8.33 khz radios, the need to switch from 25 to 8.33 physically meant that an inadvertant selection could take place thus pilot changing from one to the other without switching his radio causing loss of communications and eventually scrambling of Air Defence fighters.
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Old 10th Aug 2007, 07:05
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This is a Yank rant (nothing personal galaxy flyer, just a macroscopic observation)
Perhaps if the Yanks & some wannabe Yanks started reading back the digits rather than everyday numbers then the problem of 3 readbacks would be somewhat minimal?
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Old 10th Aug 2007, 07:18
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Port Strobe:

Quite agree, Yanks are without argument, the worst radio operators in the world. This is not windup for a thread for WORST radio operators, we hold the title, period. Our slang, bad habits, use of American English is terrible. But, I still think a level change, six digits and "contact xxx" is too much.

GF
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Old 10th Aug 2007, 10:03
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Would omitting the leading "1" help
One problem with this practise is that a VHF frequency suddenly becomes very much like a pressure setting expressed in inches (which many use)

"Two nine decimal two five"... frequency or pressure setting?

Sure the practice of reading all six figures would resolve that point... but surely THAT is the point!!!
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Old 10th Aug 2007, 11:23
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If we can manage the busiest airspace in the world
Yes, of course it is.

LTP
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Old 14th Aug 2007, 14:07
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One problem with this practise is that a VHF frequency suddenly becomes very much like a pressure setting expressed in inches (which many use)

"Two nine decimal two five"... frequency or pressure setting?

Sure the practice of reading all six figures would resolve that point... but surely THAT is the point!!!
Agreed. Please read all six digits, I'm all alone and my chimp brain has enough of a problem without adding or subtracting. It seems simple but with a load of other things going on it's not.
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Old 14th Aug 2007, 16:50
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I'll admit to knowing nothing about the technicalities or regulations re: reading out/reading back "next frequency", but I have noticed at LPL controllers have gone from saying:
"...contact Manchester on 128 decimal 35"
to
"...contact Manchester on 128 decimal 350"

This additional zero is now also added to "119.85" now "119.850" and "126.350"

Any reason for this? New regulation?
 
Old 14th Aug 2007, 17:05
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Yes.......
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Old 14th Aug 2007, 19:05
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The reason behind the regulation is simply to distinguish between the 25kHz frequency xxx,350/or the 8.33kHz channel xxx,355 or for example ,850/,855. In those cases both selections would most propable put you through readable to the right controller.

Problem is:
If you select ,850 (25kHz) instead of ,855 (8.33kHz) you will most propable also cause/recieve interference on the ,835 and ,860 which uses the same carrier. And of course they are propably allocated within recieving range otherwise the switch to 8.33 wouldn´t have had any benefit in that area for those freqs...
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Old 14th Aug 2007, 19:20
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Would omitting the leading "1" help
One problem with this practise is that a VHF frequency suddenly becomes very much like a pressure setting expressed in inches (which many use)

"Two nine decimal two five"... frequency or pressure setting?

Sure the practice of reading all six figures would resolve that point... but surely THAT is the point!!!
Why would you confuse it with a pressure setting or anything else for that matter?

"Contact London Control 27 decimal 430"
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Old 15th Aug 2007, 12:28
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Completely agree. There is no need for a '1' for VHF frequencies - everyone on the ground and in the air know that VHF freqs start with '1' so why bother saying it; if you have to go to UHF (mil leaving the civil system, for example) it can be made quite clear that UHF is to be used. Even then, 876, you go step too far by including the '0' - unecessary RT clutter.
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Old 17th Aug 2007, 02:45
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Heathrow Director

Thanks for the advice, a bit too long in India during monsoon. I'm home now and much better.

GF
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