Tony Drury

Fri, 12 Jun 2020 11:44:39 +0100

Runways are designated by a number between 01 and 36, and are given as QDM – their magnetic heading: a runway numbered 09 points east (90°), 18 is south (180°), 27 points west (270°) and 36 points to the north (360° rather than 0°). Due to magnetic declination, changes in runway designators have to occur at times to keep their designation in line with the runway's magnetic heading. QDM is rounded to the nearest degree. The variation since 1947 and today can be quite considerable so the QDM must now be 090 – 094°/ -

In 1947 there was a 10° 30’ W difference between true N and magnetic N, in 2020 this is only 0° 40' W. See this interactive map to see how this works - the green line is 0°declination Blue negative (West) and Red positive (East) declination. Using the timeline slider your will see that in the last 100 years the green line shifts dramatically approx. 2,900km (1,8oomi) west.

Ernest Falquero

Sat, 15 Jul 2017 17:51:59 +0100

Hello... I an an Admin on a Gibraltar Old photos group on Facebook and shared some of your great photos (with a link back to this page of course). One of our members posed the following question regarding the photo of the station's map & layout: "I believe the current markings are 09 and 27, not 10 and 28." Any idea what the answer is? I thought this may have been the RNAS's own designated markings for it... but perhaps you can clarify?

Many thanks in advance!

Regards

Ernest

Royal Navy Research Archive

Tony Drury

Ernest Falquero