For those pilots who have not been flying much lately you will be interested to know that magnetic declination has changed one of Merrill Field’s (PAMR/MRI) magnetic runway designators.
Using snow shoes and winter gear a contractor ventured into the elements to replace the runway sign on the gravel/ski runway, according to Merrill Field officials.
The ski strip/gravel runway was 04/22 and is now 05/23. This runway is located diagonally between the main runways of 7/25 and 16/34.
Magnetic declination, as most pilots know, is the angle between True North and Magnetic North and varies from place to place.
The reason for the variation is due to fluid motion in the outer core of the Earth called core flux, (the molten metallic region that lies from 2800 to 5000 km below the Earth’s surface) causes the magnetic field to change slowly with time. This change is known as secular variation.
Because of secular variation, declination values shown on dated aeronautical charts need to be updated if they are to be used without large errors. For this reason runway magnetic markings also need to be updated.
According to the National Geographic Society, scientists say that the north magnetic pole is now moving toward Russia at 40 miles a year.
Merrill Field has three runways 7/25 4000X100 feet, 16/24-2640 x 75 ft. and 5/23-2000 X 60 ft. located in downtown Anchorage has 880 aircraft based on the field and completed 123,553 flight operations from March 2011 to Feb. 2012.
Located only 370 miles south of the Arctic Circle its coordinates are N61 degrees 12.86’ by W149 degrees 50.77’
Rob Stapleton can be reached at: robstapleton (at) alaska.net