Age of magnetic variation data on CAA charts
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Join Date: Apr 2000
Location: London, UK
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Age of magnetic variation data on CAA charts
I'm currently writing a batch routine to update magnetic variation data based on future dates and differing models with the raw data being lat/long co-ordinates.
My initial findings are somewhat scary, the magnetic variation data on my 2004 chart is probably about 10 years old.
Can anybody confirm it's exact age?
Many thanks.
My initial findings are somewhat scary, the magnetic variation data on my 2004 chart is probably about 10 years old.
Can anybody confirm it's exact age?
Many thanks.
PPRuNeaholic
Join Date: Jun 2000
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I can't help you directly but, if the UK CAA complies with ICAO Annex 4 then the magnetic declination shouldn't be more than 5 years old. The 5-year cycle is based on years that are divisible by 5, so, e.g. ... 1980, 1985, 1990, 1995, 2000, 2005, etc. There's a caveat or two on the 5-yr cycle, but that is the basis of the whole thing.
Which particular 2004 chart would this be? My 2004 CAA S England 1:500,000 has variation lines for July 2004, with an estimated decrease of 7 minutes per year. All stated in the legend in the bottom left.
