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Friday, December 30, 2016

Moose Creek Idaho

Moose Creek 2015

Marc likes to fly to obscure, out of the way places, and you can't get much more obscure or out of the way than Moose Creek, being as it is smack in the middle of the Bitterroot Mountains.

Idaho Aviation Association has a map. Starting with their coordinates I made my own.

Moose Creek Airstrip
What looks like a wrecked aircraft is not, it is just sitting in the shadow of the trees.
The coordinates I started with had five digits after the decimal point, and put us in the river at the Southwest end of the airstrip, so I decided to see how many decimal places you actually need. The markers on the above map are one one-thousandth of degree (.001) apart. Vertically (North-South) they are 363 feet apart, horizontally (East-West), they are 253 feet apart. So four decimal places would get you within 30 feet of a point, five decimal places would get you within 3 feet, and six decimal places would get you within a few inches. For purposes of navigation, three decimal places are plenty.

Computers don't care, one floating point number is as good as any other, but due to people wanting to use the decimal system and computers using binary, translating a perfectly good decimal number to binary and then asking the computer to display it can result in values that have a dozen digit after the decimal point, and most of them are just noise.

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