Runway Designations rounding up / down
 

Hi chaps, noticed that the cross runway at Glasgow was redesignated from Runway 10 / 28 to 09 / 27 due to magnetic drift. Understood that, so far so good. However on the chart below, http://www.ais.org.uk/aes/pubs/aip/p...s/32PF0201.PDF

the magnetic headings are 096 / 276 degrees.
Why then is the designation rounded down?

If it is embarrasingly obvoius please feel free to point and laugh but I have googled well on this one.....

cheers

Skipness 1E,
Can't get anything from your link, and without more information on where and when you got your information about the change it's difficult to help. Probably there is a time delay between the airfield operating authority re-designating the runway, and this information being passed on and published in the various charts. Something to do with AIRAC cycles?.
We certainly have problems getting our chart authority (Aerad) to keep up to date with our changes, and on the latest issue following a variation change, they have published some charts showing two degrees, and some with three degrees. And on the charts where they have got the correct variation, they have forgotten to amend the runway QDM! So a warning to aviators - charts may not always reflect the true state of play.

Normal procedure is round up if it's more than 0.5 deg and round down if it's less; as they calculate the magnetic QDM to the nearest 0.1 it's rare to have a runway that's exactly on the 0.5 deg mark.

So why on the latest aerodrome charts on the www.ais.org.uk website for Glasgow is the runway correctly given as 09 / 27 and the headings marked as nearer 10 / 28 which it used to be?

I was under the impression that the runway heading is truncated to make the designator, not rounded. So 091 becomes 09 and 099 also becomes 09.

ryl