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Pilots: when can you start seeing the curvature of the earth? Sky black?

Pilots: when can you start seeing the curvature of the earth? Sky black?

Old Dec 7, 06, 9:34 pm
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Pilots: when can you start seeing the curvature of the earth? Sky black?

Flying at ~40,000 feet, my brain can see (or imagine) a very subtle curvature of the horizon.

Am I just imagining this, or is the curve there to perceive? Any pilots care to chime in about when they can notice our ball?

Related: at what point does the sky head toward black? I"ve noticed at the highest altitudes, if you look straight up, the sky has a very deep dark cast to it. Not black, but getting there. This is only on the highest-altitude flights I've been on where we were driven further up by turbulence.

-KF
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Old Dec 8, 06, 3:08 am
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Not a pilot, but...

The curvature of the Earth was visible on my Concorde flight, along with the darnkess of the sky. It wasn't black but very dark blue. I have not been able to see either features on a normal flight up to 40k
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Old Dec 8, 06, 7:44 am
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The answer to your second question is easy...the sky starts to turn black once the sun is lower than the horizon, regardless of what altitude you are at
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Old Dec 8, 06, 8:47 am
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From a friend who was a military pilot, and from sources such as the many books I have read on the SR-71 and U-2 it can be said that this doesn't appear until you get up to 55K-60K feet........

The highest I have been is 41K on a 777 and I couldn't see anything but a flat horizon.
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Old Dec 8, 06, 12:57 pm
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I am an airline pilot, and the highest I have been is 41000'. Can't say that I have noticed any curvature. Not that I have been specifically looking for it either though. I would also guess that one would have to be at least 20 miles up to notice a curve without any instruments.
Cheers

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Old Dec 8, 06, 10:17 pm
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I have observed this subtle almost-curvature of the earth at the moments when dawn has not occurred but is almost ready to do so. Back in the day when we could open a window shade, this was my favorite part of watching the fading night sky for that first intimation of color - and with it the slight line of curvature.
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Old Dec 8, 06, 11:10 pm
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Originally Posted by topsy1970 View Post
I would also guess that one would have to be at least 20 miles up to notice a curve without any instruments.
As the other poster said and as I have heard from two different people, the curvature was plainly visible from the Concorde.
Originally Posted by MDSD View Post
Back in the day when we could open a window shade
Is there some new rule about this?
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Old Dec 8, 06, 11:16 pm
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Semi-OT, but I didn't know that there was a still a "flat-earth" society out there...!

http://en.wikipedia.org/wiki/Flat_Ea..._Earth_Society
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Old Dec 8, 06, 11:20 pm
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The scientific evidence eventually overwhealmed them. Much like what will happen eventually to people who that things don't evolve.
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Old Dec 8, 06, 11:39 pm
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You could see the curvature of the earth every day while travelling on Concorde....

... until some ["#&@# morons at Airbus, Air France and in the French Government decided to ground them. BA had to follow as the cost of spare parts supplied by Airbus for the small number of frames would become way too high.

Most have forgotten Concorde. We miss her dearly. The skies are sad without her.
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Old Dec 9, 06, 12:22 am
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I am adding a link to a picture. The curvature of the earth seen from onboard British Airways Concorde G-BOAD.

http://myaviation.net/search/photo_s...417&size=large

This is what they have scrapped.

I am afraid it will be a long time before a passenger aircraft goes up above 60+K feet.

We miss you, Concorde. You will forever be the Queen of the Skies.
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Old Dec 9, 06, 9:32 am
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Originally Posted by MDSD View Post
I have observed this subtle almost-curvature of the earth at the moments when dawn has not occurred but is almost ready to do so. Back in the day when we could open a window shade, this was my favorite part of watching the fading night sky for that first intimation of color - and with it the slight line of curvature.
Now that you mention it--I've seen this slight hint of curvature while standing on the ground! I was about 18,000' up and looking towards the impending sunrise. There was a line of fire separating the ground from the not quite as dark sky. Thinking back on that scene the line of fire wasn't quite flat.
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Old Dec 9, 06, 10:14 am
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My father used to travel on Concorde. When asked about seeing the curvature of the Earth, he thought it was pretty imperceptable, albeit beginning to become noticable, and probably due more to the power of suggestion or camera distortion than anything else. He thought, apparently, you have to go up in the likes of U2 aircraft (70,000 feet) before one really has a spectacular view of the Earth's curvature, although of course the view from Concorde certainly was unique and spectacular. I only flew it once when a child.

It might also be a very subjective thing, "seeing" the curvature of Earth. Technically, one could see this on a beach as a tall ship approaches over the horizon. This would be even more true in the open ocean, where one has an unobstructed view in all directions, when some people I know have claimed to be able to see the curvature. Or as others have said, just before dawn or right after dusk when a thin sliver of light remains. Being above the weather, even in subsonic aircraft, also seems to reinforce the perception of being able to see the Earth's curvature, which certainly was true of Concorde.

But I've never seen any photos from any civilian aircraft as spectacular as some of stuff coming from weather balloons and military aircraft. If commercial space travel ever becomes viable, I would want to do it just to see sights such as those. ^
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Old Dec 9, 06, 12:53 pm
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Is there some new rule about this?
(back in the day when we could open a window shade)

Indufan, no new rule, of course, but AA FAs are vigilant about the possibility of light entering the cabin, esp. on night flights eastbound.
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Old Dec 9, 06, 1:00 pm
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Originally Posted by sdsvtdriver View Post
Not a pilot, but...
I have not been able to see either features on a normal flight up to 40k
You can see it more clearly by holding an 8.5 x 11 up to the window and comparing if the earth's horizon and the paper's edge fully align.

At 40k feet, I've noticed a slight deviation begin to become visible this way...
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