# Longitude errors in flight planning of mission planner

Everyone and especially Michael,

I believe that APM mission planner has an error in calculating flight plans in terms of correcting for longitudinal distances with respect to latitude. For instance, if you create north south flight lines in flight planner on the equator, the line spacing between lines will be correct. But as your flight plan moves off from the equator, the distance between divisions of longitude decreases, and I don't believe this is properly corrected for in 1.1.86 version of mission planner. A north south flight plan with 100m line spacing on the equator will be 100m, but in Fairbanks Alaska it will be 230 meters.

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cn you give me a example? ive tested and cant find an issue. all my functions include lat scaling.

The Haversine formula, http://www.movable-type.co.uk/scripts/latlong.html

is the formula used

ok, i see what you mean now

im not sure what it is, but it doesnt do it every time.

That seems particularly strange, that it is intermittent? Once I noticed the issue today on a project located about 37 north latitude, I tested one on the equator and in Fairbanks Alaska to confirm the issue, and the equatorial distance was correct, but both the Fairbanks and California plans were incorrect and progressively so as the latitude increased. California distance was around 124m when it should have been 100m, and Fairbanks was 235m when it should have been 100m. Note that it only applies to off equatorial locations and only for north south flight lines (I probably entered 0 for an angle, but I don't think I tried 180?), not east west.

my first though is it might have to do with zoom level, but i cant confirm that

if you find a way to make it happen every time, im intrested. otherwise im chasing my tail.

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