UK ATC communication

[oceancrosser]

Gentlemen and/or Ladies :ok:,
I have long been surprised and bothered by the low quality of VHF voice communications with UK ATC (Scottish, London). Generally it sounds like some of the controllers have their head in a steel drum. Not all the time though, which has me thinking whether this is a headset / type of mic issue?
But overall the quality of transmission from UK ATC is about the worst in Europe. Any credible explanations?

[goatface]

Or possibly the quality of the radios fitted to your fleet of aircraft?

On the whole the quality of VHF radio coverage in the UK is pretty good and equipment we use on the ground proven to be of good quality.

It would be interesting to know if the problems you encounter are more specific to one particular sector of the UK.

[oz in dxb]

I have to agree with Oceancrosser. Most of the London controllers sound like they are in some shed out the back of Timbucktoo!
I'm not sure if it's the headphones they wear but it is distinctly London calling!

Oz

[HEATHROW DIRECTOR]

The R/T quality of Heathrow Approach deteriorated dramatically when we moved to West Drayton. OK, the microphones were of a slightly different design but they shouldn't cause the sort of problems crews were experiencing. We had repeated complaints - and that was 16 years ago so I'm somewhat surprised if it hasn't been fixed.

[anotherthing]

HD

Don't be so surprised. I've just come off a nightshift and one of the engineers who happened to be in the Ops room was bemoaning the VCCS that is in TC as it causes them (the engineers) so many problems.

As ATCOs we are able to use it, though not to its full potential, though it is not very robust. Seems like the engineers in the background are working very hard just to maintain it at that level. There is probably not a day goes by without at least one comms panel having to be reset due to errors.

[radarman]

This has been a problem at a couple of units I have worked at. I think it boils down to the fact that after leaving the mike the controller's instruction doesn't go straight to the transmitter, like in the old days. In most modern systems it goes through a number of computerised processing and switching circuits, each of which adds a certain level of compression and distortion of the original signal. It is probably digitised at some stage as well, which won't help matters either.

[Mooncrest]

Something that may be significant.

Last year I bought a used Racal Astrolite headset, ostensibly in good condition. The electret microphone fitted was the original and was, frankly, terrible. I managed to open the housing and replace it with the same type of mic which cost me about £2.00. Result - excellent. Far superior output. NATS used these headsets at West Drayton and LHR some time ago, so it could be simply a problem of dodgy microphones. I'd hope not coz ATC headsets don't come cheap, whoever the manufacturer is.

[oceancrosser]

Or possibly the quality of the radios fitted to your fleet of aircraft?

On the whole the quality of VHF radio coverage in the UK is pretty good and equipment we use on the ground proven to be of good quality.

It would be interesting to know if the problems you encounter are more specific to one particular sector of the UK.

Well goatface, the other replies here seem to suggest otherwise. "My" fleet of around 20 different a/c, about half sourced from other airlines seems to have this problem throughout. VHF coverage in the UK is not the problem. I fly through all of the UK airspace regularly and into GLA, LHR, MAN, EMA.

It makes no difference how good your transmitters are, if the mic´s are rubbish, the transmission will be rubbish, however the opposite also holds true.
Sidetone usually gives oneself an indication of quality of transmissions.

On some arrival/approach sectors, 2 controllers can be heard. There can be vast difference in the quality of the communications. That leads me to the mic´s (headsets).

[oceancrosser]

Finger trouble.... sorry!

[pottwiddler]

CAP670 Com 03 clearly states the specifications that the Voice Communications Control Systems must meet. And by and large they do! Otherwise they wouldn't get approval.
Equipment nowadays are sourced from Europe, the major VCCS manufacturers are either an Austrian, German or French Company using 'standard' transmitters, the Air Traffic Engineers carry out regular servicing on the VCCS, the Transmitters and indeed the Receivers using tried and tested methods of quantifying line levels, distortion, signal to noise etc which is all traceable using UKAS calibrated test equipment.
As for Headsets, the majority of VCCS manufacturers lay down a spec, which the headset manufacturers work to and comply with. The VCCS manufacturers somtimes endorse that particular headset and some even supply the headset when you purchase the VCCS, so I cannot how you percieve that ATC can talk to you with their heads in a bucket.

I've heard them talk out of another orifice but that is another subject.....:oh:

[Spitoon]

CAP670 Com 03 clearly states the specifications that the Voice Communications Control Systems must meet. Well, it sets the minimum standard the the equipment must meet. But if the VCCS uses software there are other minimum standards that must be met.....and if what anotherthing says about resets is correct it's doubtful that the software is of adequate quality.

And then there is the SMS that the ANSP has to operate...which should seek to continually improve safety levels. Unless of course someone has determined that reliable voice comms are not particularly safety-significant.

[Jumbo Driver]

oceancrosser, could it be related in some way to receiver incompatibility with offset-carrier operation (http://www.nats-uk.ead-it.com/aip/current/aic/pink/EG_Circ_2008_P_072_en.pdf) ... as I understand that the offset-carrier system is not compatible with 8.33 kHz operation ...


JD
:)

[Lon More]

CAP670 Com 03 clearly states the specifications that the Voice Communications Control Systems must meet.

It would of course be impossible that NATS bought sub-standard equipment then the CAA wrote the regs. around it?

[HEATHROW DIRECTOR]

<<so I cannot how you percieve that ATC can talk to you with their heads in a bucket.>>

Well, you want to have a listen because that is precisely what it sounds like sometimes!

[Not Long Now]

Personally speaking, since we (TC) moved down from West Drayton, I think the RT is much worse quality and far more subject to cross calls being missed. Apparently it's not though, and that's just a perception felt by everyone who uses it all day every day, and I know that 'cos it said so on a piece of paper from someone in an office. There was a very slight improvement after some tweaking about mid last year, but still way off the old quality we used to have in the steam age of WD.
And as for the VCCS system, let's not start...

[Mooncrest]

Sound quality can vary even when the same VCCS is being used. For example,
both LBA and MAN airports (can't speak for MACC) use the Schmid ICS system but the audio from MAN is superior to that of LBA. Could be that MAN use more powerful transmitters or, again, it may be down to headset mics, type and so on. So many variables to consider.

Personally, I loved the old British-made lever keys and lamps, VOGADS and things. Sadly, largely confined to the dustbin now. :{

[radarman]

Pottwiddler,
Compliance with technical specifications does not necessarily equal good quality. Whenever we get our radar back from annual servicing the electronics are reset to specification but the picture is crap. The local technicians spend weeks tweaking it so we get decent returns, but the gear is then often 'out of spec'. Not belittling the 'advances' made by modern equipment designers, but when I started controlling everything was analogue with valves. Talking to a Victor pilot on the old ARC52 was like having the guy sitting chatting next to you. Modern stuff has too many clever electronic gizmos b*ggering up the sound quality.

[Inverted81]

Going in a slightly different direction, a similar thing can be said about aircraft radios. I tend to work many different types a day, and there are HUGE differences from airframe to airframe even from the same type operated and maintained by the same company. One observation i have made recently is that more "modern" airframes have fantastic radio quality. Speaking to an SR22 or a Typhoon, is really like having the pilot sat next to you. (in fact it can be quite creepy sometimes as no engine noise whatsoever!!).
With regard to ATC headsets, ours frequently break and get sent away for repair. Mine has come back twice from repair over the last few months, only to have developed a new problem on its return (mines going back in tomorrow for a new PTT switch :ugh: ) ..... ah well, credit crunch and all that no money for the basics anymore, according to those "higher up"........ :ooh: