The delays aren't a problem because you could do this even if there was minutes of delay due to planes often flying in a straight line. It's true that dead reck

The delays aren't a problem because you could do this even if there was minutes of delay due to planes often flying in a straight line. It's true that dead reckoning doesn't work for large distances, but would be mostly correct for ~100km estimations. I once tried something like that for a few hours, the project got stuck but the idea was to predict when a plane will be on a radius from you, then trigger a notification when it should be around the estimated location (and actual "cone" of visibility in my case), but only if the actual position of the plane then is around the estimated location. This way you shouldn't get repeats. Either way, repeats could be easily filtered out in many ways. Point of project was more of a "plane bingo" because for "my country joining NATO" reasons there was suddenly more interesting warplanes flying around visible to my teleoptics from my flat.