RWY designator and QFU

[mrmum]

Does anyone know the rules (if any) that govern the relationship between the actual runway direction and what the operator chooses to call it?

I would expect a runway designated as 27, to have a magnetic bearing of 265-274.99 degrees. I am aware of a licensed airfield which has runways with QFU's 7 degrees less than the designators. Obviously they would have been correct at some point in the past, but with the rate of change of magnetic variation we experience, it should have been re-designated and the numbers repainted some years ago.

Depending on how long this kind of situation is allowed to continue, you could end up with pilots getting noticeably higher crosswinds than expected, as the runway direction isn't what it appears to be.

[Whopity]

ICAO Annex 14 recommends that Runway designators should be to the nearest 5 degrees measured to the nearest 1/10 of a degree.

Any runway outside these parameters would not meet Certification and in the UK, Licensing requirements.

The runways True direction will not change and a pilot should be quite capable of estimating the crosswind regardless of what is written on the end of the runway. How accurate do you think the wind is?

[DFC]

ICAO Annex 14 recommends that Runway designators should be to the nearest 5 degrees measured to the nearest 1/10 of a degree.




The runway direction is surveyed to 1/10 of a degree (True).

The magnetic variation and declination is also surveyed and applied to this to give the magnetic direction of the runway.

The runway designator is - as specified in Annex 14 - the whole number nearest to 1/10 of the magnetic direction of the runway.

i.e. Magnetic direction is 234.9 then 1/10 of this is 23.49 which gives 23 as the designator.

When printing the magnetic direction it will be 235 - and you will be thinking that it should be runway 24?

Having said that, when it comes to runway direction it is the magnetic direction of the runway that counts and not it's designator because in the case of multiple parallel runways all with the same direction eg 234.9, we would have;

22L 22C 22R 23L 23C 23R 24L 24C 24R

As you can see that while 23C has a magnetic direction of 234.9, so too does 22L and 24R in this example.

If you are worried about the crosswind, you need to have a look at what is actually reported.

Start with the fact that a gust is not reported until it is 10Kt above the mean. So for your runway 27 a wind of 360 at a speed varying beyween 1 and 19 is reported as simply 360/10.........but you tell me what you do when it goes from 5 to 19 quickly when your crosswind limit is 12 knots?

Add to that the fact that you are only told of a variation in direction when it becomes significant i.e. spreads over a 60 degree + band and a host of other met reporting and forecasting issues and you will find that being +/- 10 or even 20 degrees is not going to make that much of a difference.

[mrmum]

Whopity & DFC,

Thanks for the info, that's what I was looking for, and I concede your crosswind comments are fair enough.