Runway Numbering Philosophy
 

Not sure if Passengers and SLF is the best sub-forum for this question, but it seems like a good starting point.

I have a bit of a strange question about runway numbering philosophy for parallel runways (I do understand the numbers relate to magnetic heading). Obviously for a pair of parallel runways they are designated L and R, like Heathrow. And where there are three parallel runways, like Amsterdam for example, they are designated L, C (for centre) and R. But what happens when there are four or more parallel runways?

The reason I ask is that I have recently passed through the new Istanbul airport, which has 5 runways all of which appear, at first sight, to be parallel. But on the journey home I noticed that we took off from runway 36 (i.e. 18/36) – no suffix. I was curious about this so I looked up the actual runway numbers, which turn out to be 16 / 34 L & R, 17 / 35 L & R, and the aforementioned 18 / 36. And I assume, though willing to be corrected, that with more than three runways the designation of L, C and R can no longer be expanded and a different solution needs to be found. If I’m correct, are some of the runway numbers ‘notional’ or do they genuinely need to be built with a 1 degree change of orientation?

Hi Andy,

The runways in Istanbul are parallel. The latest ground chart I have shows they’re all on a magnetic heading of 354 degrees. The airport authority in association with the Turkish CAA has decided that this is the best way to number the runways. I think even more runways are planned which may see runway 18/36 become a L/R or C in the future too!

Paris CDG is another where the runways to the north of the central area are 09/27s and the southerly ones are 08/26s despite all being on the same headings.

Essentially, it’s a best practice to number them based on the magnetic heading but slight differences are allowed especially if runways are grouped to reduce the chance of confusion (I.e. 34L and R are next to each other, then 35L and R etc).

Just to confirm what champair79 already said, here is Dallas, with 5 runways on the same magnetic heading, numbered as 36 L/R and 35 L/C/R.
https://www.faa.gov/air_traffic/publ...2.0_texas.html

Hi Champair. Great answer, thank you for the explanation.

Common sense tells me that if you start to number parallel runways 36LL / 18RR or 36L1 / 18R1 for example it introduces the potential for potentially dangerous confusion

Yes and the magnetic heading is only approx anyway - quite a few US small medium airports have approaches that are 10 degrees (or more) magnetic off the runway heading. They just annotate the Jeppesen approach plate

Runways in Greenland aren't numbered. The North Magnetic Pole wanders across northern Greenland sometimes, and the magnetic variation can vary from day to day. I spent an enjoyable summer in Greenland installing a microwave link, and you don't align the dishes with a compass, you use a sextant. In the summer, the sun is always above the horizon north of the Arctic Circle, and even through cloud you can take a bearing. When you go further north, e.g., Cape Morris Jesup, the compass needle points south or west.

LAX is another example, 06/24 L&R north side and 07/25 L&R south side.

Good question, never thought of that before!

Well, that's an interesting: Observation; Question; Answers.

Thanks to all and Andy_S for asking the Cabin. It seems we know a fair amount in here!

It's only from PPRuNe that I learnt that some runways are renumbered from time-to-time due to magnetic North moving. You learn something every day.

If you watch the youtube I put up in the thread 'Old LHR T2' you'll see that the runway was 10L or 10R in the 1960s. It's 09 L and 09R now.

[/QUOTE]Runways in Greenland aren't numbered.[/QUOTE]

Sorry, but they are in Narsarsuaq, Kangerlussuaq, Nuuk and Pituffik. Kulusuk, however appears not to be numbered. Look them up on Google Earth.

Runways in Greenland aren't numbered.[/QUOTE]

Sorry, but they are in Narsarsuaq, Kangerlussuaq, Nuuk and Pituffik. Kulusuk, however appears not to be numbered. Look them up on Google Earth.[/QUOTE]

It's 30 years since I was there so I suppose someone has been round with a bucket of paint in the interim.

Another slight oddity in the runway numbering system is that runways worldwide with a rounded magnetic heading in the range 010° to 090° will have "01", "02", etc, up to "09" painted on the threshold - except in the US where they omit the leading zero and simply paint them as "1", "2", up to "9".

The US has a tendency to approach in a slightly different manner.

ICAO Annex 14 refers.... up to three parallel runways can use L, R and C, thereafter one set is rounded to the nearest 10 degrees, the other set is rounded to the next nearest 10 degrees, (theoretically) opening up the options to have up to six parallel runways. You will run into some confusion no doubt, which is why Istanbul has used a slightly different version and uses three sets of numbers for five runways.

Yes, IST has three groups of runways (with, from W to E, 2, 2, and 1 runways) separated by terminals between each group. So there's no scope for a C runway designation, therefore three separate runway direction designations are used.

What has been odd is that the magnetic north stared moving very rapidly in the 1980's - it now seems to have slowed somewhat. Hence the need to keep altering the paintwork

https://cimg8.ibsrv.net/gimg/pprune....bb4e017272.jpg
https://cimg0.ibsrv.net/gimg/pprune....3b5d46b6ce.jpg

Fascinating stuff. Thanks!

It looks like the Magnetic North has been working hard to get as far as possible away from the USA ...

It's justt trying to go South for a warm holiday...