Today is 24 September 2018, the 267th day of the year.



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Civil Smith, a regional director of the Federal Aviation Administration, is tasked with choosing flight paths for commuter flights among five regional airports. There are to be flights from each airport to each of the others, so a flight path must be designated between each pair of airports. (Fortunately, there will never be flights going in both directions at once between any two airports, so only one path is needed.) Since the commuter planes will all wish to fly at altitudes between 10,000 and 14,000 feet, it will be safer if none of the flight paths cross. However, try as he might, Civil can't seem to come up with a set of paths that doesn't involve at least one crossing point for two or more of the paths.
Today's challenge: Can you help Civil come up with flight paths among all the five airports that don't cross over one another at any point, or failing that, prove that it can't be done?


Solution to yesterday's challenge

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