# A question about the coordinate system

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How do you determine the midway point between two coordinates? For example, how would I determine the middle point between 41.8677777, 87.2780555 (which is N41*52.04, W87*16.41) and 41.8677777, 87.2663888(which is N41*52.04, W87*15.59). I'm not very good at all this so please explain it as if you're talking to a newbie.Thank you very much.

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As with every in aviation "half-way" comes in several different units.There is the geographic "half-way" which is a point on the route where the distance measurement is equal...pretty simple there (see the link in the other response on this thread).HOWEVER (and there always seems to be a "however") there is the much more important "half-way" measured in hours. This is a fun one to figure because it is based on winds aloft and varies day-to-day,hour to hourch more important to long hauls due to the impact on fuel burns and required fuel reserves when landing.In the old 747-200 days when flying DWT/ORD to Narita our release point was to a point 300 miles west of Anchorage where dispatch and crew would take a "how-goes-it" and determine if we had enough fuel on-board to "legally" make it. If we didn't we would turn back to Anchorage for a technical stop and gas-up.Now with ETOPS(Engines Turns Or Passengers Swim) figuring the effects of winds and various options much more "critical" to safe operations.This is one of the reason why long-haul flights have a much longer planning session then a domestic run....with a lot more "barin-teazers".Tim757

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Thanks for the information, Toreb and Tim.Christine

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