Well this is for a flight simulator and all the distances will be usually within one geocell. So most of the straight line measurements will do just fine. But I've heard of great circle math. Is that something I should consider? Because if you travel 0.3 degrees at 5000 feet above sea level that's represented differently than 0.3 degrees at 1000 feet above sea level right?

Edit, I click the link you posted after my reply and the first thing I see is great circle navigation. Lol
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