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3 Answers

How fast would an aircraft have to fly to keep the sun on the horizon?

Asked by: 6751 views General Aviation

They say that no question is stupid, so here it goes. How fast would an aircraft have to fly to keep the sun on the horizon, say on a route across the SW USA, East to West? I have flown at sundown many times from Pit to LA and just wondered if you could possibly keep up with the sun?

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3 Answers

  1. tresclements@msn.com on Jul 26, 2010

    This is a pretty straight forward question that I have pondered in the past. The math is pretty simple for an approximate answer. All you need to know is the circumference of the earth where you plan to fly.

    According to a quick google search the circumference of the earth is ~24,859.82 miles so I am going to assume that since you will be north of the equator this would be about the same at altitude. You can spend more time dialing this number in if you want.

    All you have to do is divide the circumference or miles around the earth by the number of hours in a day. So 24 859.82miles / 24 hr= 1 035.82583 miles/hr

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  2. Paul on Jul 26, 2010

    1035 assumes the flight is on the equator. If it was further north or south the circumference is obviously less.

    At mid latitudes during the summer it would be about 730 miles per hour or about .95 mach (faster than a Citation X!) You might have to get up quite north to have a Citation X keep north.

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  3. EML on Feb 21, 2015

    At altitude (let’s say 35000 feet) you would have to fly @ approx 1690 mph to keep up with the sun

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