I am aware that you can calculate distance between two lat/long coordinates, but although it takes in to account the curvature of the earth how does it create an accurate measurement given the altitude difference between the two lat/long points?
eg, say you you have 2 lat / long points close by, but you have climbed 3 miles to get from one to the other, then surely the distance that the GPS says you have travelled must be incorrect?
Thanks

