Runway designators, UK

[FRatSTN]

I don't really know much about magnetic variation, but does anybody know how fast the magnetic change is in the UK? I seem to make it a 1 degree change about every 5 years but not sure if that's right.

I ask because Luton's magnetic heading for RWY26 is only 256 degrees and Prestwick's RWY31 is 306. These values are decreasing so how long can we expect before we see Luton become 07/25 and Prestwick's main runway 12/30? In other words, before it falls below 255 and 305 respectively?

[TCAS FAN]

You can check in UK AIP AD section which lists the annual change in magnetic variation ay each licensed aerodrome.

NATS | AIS - Home (http://www.nats-uk.ead-it.com/public/index.php%3Foption=com_content&task=blogcategory&id=6&Itemid=13.html)

[DaveReidUK]

I would estimate that Prestwick's 13/31 should be redesignated 12/30 within the next couple of AIRAC cycles.

Luton in about 5 years' time.

[whitelighter]

Magnetic variation in the UK is decreasing by around 3-5 minutes annually as an average

[Spitoon]

I would estimate that Prestwick's 13/31 should be redesignated 12/30 within the next couple of AIRAC cycles.Just curious, but why do you say this?

[DaveReidUK]

Just curious, but why do you say this?Prestwick's main runway is oriented approximately 121.4°/301.4° (true). Add the current declination of 3.7°, reducing by about 10' per annum, and you're already almost at the 125°/305° (magnetic) point below which the designator will become 12/30.

[Burnie5204]

RAF Syerston had to change its runway designations about 2-3 years ago.

RW25 became RW24,
RW34 became RW33,
RW31 became RW30

And obviously the reciprocal runways too.


When they changed we were told we could all look forward to it again in another 10-15 years.

[DaveReidUK]

When they changedInteresting. It's very unusual for more than one runway at an airfield to change designation at the same time, unless of course they are an exact multiple of 10° apart.

we were told we could all look forward to it again in another 10-15 years.Sounds very unlikely.

[Spitoon]

Prestwick's main runway is oriented approximately 121.4°/301.4° (true). Add the current declination of 3.7°, reducing by about 10' per annum, and you're already almost at the 125°/305° (magnetic) point below which the designator will become 12/30.Changing the runway designator is no small undertaking and it could conceivably be deferred until some other scheduled works are to be done.

There's also the point that, to an extent, the designator is an identifier of the runway rather than an indication of its direction. I seem to recall hearing of parallel runways given designators suggesting that their direction differs by 10 deg in order to avoid potential confusion between L/C/R. Similarly, I recall hearing of a 13/31 being redesignated to overcome the human condition where it's just a little too easy to transpose the numbers in our heads.

[DaveReidUK]

I seem to recall hearing of parallel runways given designators suggesting that their direction differs by 10 deg in order to avoid potential confusion between L/C/R.Yes - the ICAO standard is only to use those 3 letters, so it follows that any airport with 4 or more parallel runways has to adopt the convention where no more than 3 are given the same designator, and additional runways will be given the next nearest number.

So, for example, Paris CDG has 08L/08R and 09L/09R, all with the same heading.

[FRatSTN]

Interesting. It's very unusual for more than one runway at an airfield to change designation at the same time, unless of course they are an exact multiple of 10° apart.


Humberside did it about 3 or 4 years ago. They changed 03/21 to 02/20 and 09/27 to 08/26 at the same time.

Stansted and London City both changed theirs on the same day. July 5th 2009 if I remember correctly! I listened to London City ATIS for the first time that day and when it said runway 27, I was really confused!!!

[DaveReidUK]

Humberside did it about 3 or 4 years ago. They changed 03/21 to 02/20 and 09/27 to 08/26 at the same time.That would make sense - runway headings are 22.36° and 82.45°, so within a gnat's of 60° apart (as was common for airfields built during WW2) and it would have made sense to coordinate the changes.

Stansted and London City both changed theirs on the same day.Yes, same applies here - 42.90° and 92.89°, with more or less the same declination so the change would have taken effect on the same AIRAC cycle date.

[HEATHROW DIRECTOR]

To add to the fun. London Airport's runways 16/34 changed to 15/33 in 1952. On 2nd July, 1987 Heathrow's 28/10 changed to 27/09. I know - I was there! The airport authority hitched up every tractor they could find to drag the runways round to their new headings, but it wasn't enough. Luckily, I had used my wife's Reliant Robin for work that night and we hitched that up too and its immense power soon had the runways lined up...

[DaveReidUK]

Luckily, I had used my wife's Reliant Robin for work that night and we hitched that up too and its immense power soon had the runways lined up... Might need a few Reliant Robins for this realignment project, too:

Northolt floated as runway alternative | News | Travel Trade Gazette (http://www.ttgdigital.com/news/northolt-floated-as-runway-alternative/4684351.article)

[Skipness One Echo]

Glasgow changed 10/28 to 09/27 leaving the main as 05/23.
The next thing they did was withdraw the pesky cross runway entirely.

[chevvron]

I did this exercise when we were changing Farnborough from miltary to civil specification.
I had calculated (from the rate of change notified on half million charts) that it would be sometime in 2005 when we would need to change from 07/25 to 06/24, however when I enquired, I was informed that the change in variation is calculated in 4 yearly 'epochs', and that as a new epoch was imminent, the runway would need to be re-designated in early 2003. As the runway was being re-surfaced at the time of my enquiry, we asked and obtained permission to re-designate it slightly early ie autumn 2002.

[fisbangwollop]

Skipness....Glasgow changed 10/28 to 09/27 leaving the main as 05/23.
The next thing they did was withdraw the pesky cross runway entirely.


Glasgow main runway 24/06 changed in March 1981 to 23/05 :cool:

[ZOOKER]

I read somewhere that with the present accelerating rate of change of magnetic variation, EGCC might have 01/19 within 70 years.
Like Katla and Jellystone, the next geomagnetic reversal is running a bit late.

[Another_CFI]

Having read Chevvron's comment "we asked and obtained permission to re-designate it slightly early" I now know why I had such problems with the ILS.The runway was 10° out of alignment!

[chevvron]

It's already changed to 244 deg M since then, anyway you should've done a PAR instead. When the LLZ/DME was installed (no GP) I was very careful to ensure the LLZ and PAR Az were co-incidental. We then enjoyed doing approaches with the pilots flying the LLZ whilst we passed instructions to maintain the correct glidepath!

[Another_CFI]

The Farnborough PAR is sadly missed. The skill of the PAR controllers was a joy to observe, particularly when they were dealing with an IMC student who was having problems holding headings or who had forgotten to synchronise the DI with the compass.

[tomahawk_pa38]

As a non-commercial pilot and sorry to ask an obvious question but if it's so involved, complex and expensive - why bother? As someone else said the numbers are only an indicator so what if it's 5 degress or so out ? They are bnever 'accurate' for long anyway so as long as there's no cause for confusion with an adjacent runway can't see why they bother to keep changing them which I would think causse more confusion. Just make sure the charts and flight management computersk now the right headings ! I suppose it's someone's job ?

[renard]

If runways were just called "A" and "B" for example or something which did not reference their direction would be a little harder from a pilot point of view.

When cleared to land you get "Cleared to land Rw27, wind 290/30" say. It is very straightforward to work the cross wind - 10kt more or less.

When lining up, it can nice to say 27 (Runway numbers), 27 (magnetic compass) and 27 (Nav Display) to make sure you are on the correct runway. In a light aircraft the last one would be 27 (Direction Indicator) which would prompt you to check you have set your DI correctly.

The super efficient Swiss take a more liberal line with runway designation at Zurich. Runway 34 has a QFU of 334deg, which in my book makes it runway 33!

I can't think that changing a few signs and repainting the numbers would cost much in the grand scheme of things.

[HEATHROW DIRECTOR]

<<can't see why they bother to keep changing them>>

Once in 50 years too much then?

[DaveReidUK]

The super efficient Swiss take a more liberal line with runway designation at Zurich. Runway 34 has a QFU of 334deg, which in my book makes it runway 33! I would guess that with two runways at ZRH less than 20° apart - 34 and 32 - changing one of them to 33 would be potentially confusing.