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Ask the Pilot, with Captain Mike Bowers


Q: When you are flying 35,000 feet high, what are the maximum miles that we can see on a clear day? What about 40,000? 30,000?
A: There are many factors that affect the visible distance to the horizon, including the curvature of the earth and the effects of atmospheric refraction. To simplify the answer: if we only consider the earth’s curvature, the formula for distance in miles is 1.22 x the square root of the height of the aircraft in feet. I won’t make you do the math: At 10,000 feet, you can see 122 miles. At 30,000, visibility can be 211 miles; at 40,000 feet, you can see 244 miles. Of course, if you look “above” the horizon, you can see the sun at 93,000,000 miles and light years to the stars.

Do you have a question for Captain Bowers? You can write to him at askthepilot@united.com

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