1. Graphic illustrating runway numbering with compass in background. E.g., runway 33 points ~330° NW. 2. Runway map of Boston Local airport. Source https://en.wikipedia.org/wiki/Logan_International_Airport 3. Aerial view of Logan airport runway 33 at the edge of the water as an airplane is landing.

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   AkaSci 🛰️ (akasci@fosstodon.org)'s status on Tuesday, 24-Dec-2024 18:20:48 JST AkaSci 🛰️

   in reply to

   The shifting direction of earth's magnetic field also affects airport runway numbering!

   The runway number is between 1 and 36 = round(z / 10), where z is the magnetic azimuth of the runway in degrees. E.g., runway number 33 points between 325° and 335° towards mag NW.

   In 2009, the Fairbanks International Airport in Alaska renamed runway 1L-19R to 2L-20R, when magnetic north shifted enough to mandate a change.

   Now imagine a large excursion or polarity reversal 😲

   https://www.faa.gov/air_traffic/publications/atpubs/aim_html/chap2_section_3.html
   7/n