“It’s like the first thing you learn in private pilot ground school.”
And anybody who had to learn how to read a map in the military knows the correction is printed on every map with a graphic on how to apply the correction. We just think that technology like GPS has made us smarter when all it’s done is to remove some people’s ability to think.
I loved my Loran C. It just had a few patchy void areas in transition areas. Just as accurate as my localizer and VOR. More accurate than NDB.
IIRC, most of the maps also have the predicted rate of change per year on there too. “Magnetic Declination = 6.5 degrees West, at 0.1 W per year.”
So now it might be 0.12 per year. Not a big deal when using a compass and map to find a landmark. Probably not that big of a deal in one’s car either?
Targeting of missiles using GPS, I’m guessing that extra .02 degrees at 1,000 miles may make a difference. I doubt GPS works like this, but if I used a compass to “aim” the missle, at 1,000 miles it would be off by about 1,800 feet to one side (I think I did the math properly).
BTW - the headline is stupid. “Check your compass” doesn’t help - it always points to magnetic north. Although I know that our street points directly due north - so I have double-checked my declination using the curb. Although the length of my street (or my compass marked at 1 degree marks and my poor eyes) won’t help much in figuring out that last .02 degrees!