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Magnetic shift gives JWA runways new numbers

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John Wayne Airport’s two runways are getting new call numbers, airport officials said, and the reason is out of this world — sort of.

Because the runway designations are tied to Earth’s magnetic poles, which gradually shift, the runways formerly known as 1L-19R and 1R-19L will become 2L-20R and 2R-20L, respectively, according to an airport news release.

The change was delayed from July until this month so the Federal Aviation Administration could update its reference materials to reflect the new designations.

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Pilots will have to get used to using the new call numbers, but otherwise flights won’t be affected, airport spokeswoman Jenny Wedge wrote in an email.

Both runways have had their current designations for almost 50 years, according to the release. Each number and letter combination marks one end of a runway (1R, for example, stands for one right) and the second number is always a difference of 18, to represent a 180-degree shift.

The FAA sets the calculation used to designate runways, which is based on the magnetic bearing of their centerlines, measured clockwise from magnetic north, the release said.

Magnetic north rotates about one degree every 12 years, or five degrees every six decades, so runway numbers are updated periodically.

—Jill Cowan

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