As per Wikipedia, the North Pole (NP) has moved about 231 miles in the last 4 years. i.e. 82.7 - 81.3 = 1.4 and 114.4 - 110.8 = 3.6. Now 1.4° * 60 = 84 nm and 3.6° = 216 nm. The sqrt( 84 * 84 + 216 * 216 ) = 231 nm. Since I started flying in 1972 (36 years ago), that would mean that the NP has moved 36/4*231 = 2,080 miles. When I started flying Phliy had a 6° offset from true to magnetic north and Detroit had a 0° offset. Today Phily is 12° and Detroit is 6°.
Now if we take a look at the circumference of the Earth at the NP, we get, again according to Wikipedia, sin( 90° - 82.7° ) = .127. .127 * 21,600 nm = 2,743 nm. In other words the NP has done more than 2/3 of a complete circle at its' latitude. In other words, Detroit should be back to a 0° offset in about another 10 years.
If there are any questions or problems, feel free to call or eMail.
-- Lorn H. 'Feathers' Olsen, MAA, ASMEL, ASES, Comm, Inst LNC2, FB90/92, O-320-D1F, 1,470 hrs, N31161, Y47, SE Michigan
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