TIL from the NYT crossword that airport runway numbers have directional significance, as explained in Wikipedia:
Runways are named by a number between 01 and 36, which is generally the magnetic azimuth of the runway's heading in decadegrees. This heading differs from true north by the local magnetic declination. A runway numbered 09 points east (90°), runway 18 is south (180°), runway 27 points west (270°) and runway 36 points to the north (360° rather than 0°)... A runway can normally be used in both directions, and is named for each direction separately: e.g., "runway 15" in one direction is "runway 33" when used in the other. The two numbers differ by 18 (= 180°).
Additional details (including the letter designations) at pilotinstitute.
> magnetic azimuth
ReplyDeleteIn the few decades I've had my collection of USGS maps, the magnetic declination I use with them has changed as the magnetic pole has moved. Does this imply that runway 9 might have to be renamed runway 10 eventually?
See the CGPGrey video posted by Keith.
DeleteScott Manley has an, again longish, video about the shuttle landing that missed the runway. I've linked to the point where he starts talking about numbers. Though the whole video is interesting if you, like me, were raised in the shuttle era.: https://youtu.be/AZ4UWbt6vZg?t=300
DeleteCGPGrey did a, longish, video on this topic: https://youtu.be/qD6bPNZRRbQ?si=SFd22ijZuQC0vEJA
ReplyDeleteHe also has one on the chaos of airport codes, like JFK or ATL: https://youtu.be/jfOUVYQnuhw?si=3FOPIKE9Fw24Iayr
Thanks, Keith. The answer, for anyone who doesn't have time for the video, is that they do indeed rename the runways as the magnetic north pole moves over time.
DeleteIt makes sense: in my opinion, it's simpler to change the runway number (especially as it's ±5°) than to have to "skew" all the aircraft's measuring equipment.
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