Problem with Google earth

tboehm

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Just wondering if anybody else is noticing this. Got some coordinates for my pilot on a drop off plug them in on Google earth and it's actually showing 3.85 miles off of where it actually should be. Did the same thing with the in reach and it's off on that map as well. Finally plugged it into my Garman GPS and showed exactly where it should be. This can cause a lot of problems trying to plan our hunting spots and marking locations.
 

ChugiakTinkerer

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It may be how the coordinates are read off and/or input. Is everything in decimal degrees or do you have some minutes and seconds being interpreted as hundredths and/or ten thousandths?

For example, Long Lake at the headwaters of North Fork Campbell Creek is at about
61°07'32.0"N 149°33'00.0"W


If I key that as decimal degrees I get 61.07320 N, -149.33000 W. That puts it at a point about 6 miles southeast of Long lake.


Is it possible this is the sort of issue you've encountered?
 

ChugiakTinkerer

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Wrong datum is usually good for about 200 yards differential. Not on the scale of the problem tboehm is seeing, but another thing I frequently forget is that the imagery in Google Earth is not usually orthorectified. So being off a few tens or maybe even hundreds of feet is within the range of normal.
 

iofthetaiga

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There are places here where the difference between NAD 83 and NAD 27 can put you over a ridge and into a completely different drainage.... So ensuring you're using the same datum is important.

That said, your pilot's GPS is likely displaying DEGREES - MINUTES - DECIMAL MINUTES, and confusing that with DEGREES - MINUTES - SECONDS can throw you off a fair piece too.

The third format option is DEGREES - DECIMAL DEGREES, but typically that is not used in general aviation.
 
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