A question for pilots.....

[gunnss]

I need to know how far you can see from the cockpit of an aircraft flying at 10,500 feet (roughly two miles high) I have flown this high numerous times in both balloons and small aircraft, but our launch points, "start" at 6000 feet. I need to know how big a circle you can see from this hight above sea level. My guess is around 800 to 1000 miles, but I need to account for haze and what is perceived vs reality. Also from two miles up, how much earlier would the sunrise be detectable?

Regards,

Kevin

Alt history, the butterfly made me do it.

[Serenity]

I need to know how far you can see from the cockpit of an aircraft flying at 10,500 feet (roughly two miles high) I have flown this high numerous times in both balloons and small aircraft, but our launch points, "start" at 6000 feet. I need to know how big a circle you can see from this hight above sea level. My guess is around 800 to 1000 miles, but I need to account for haze and what is perceived vs reality. Also from two miles up, how much earlier would the sunrise be detectable?

Regards,

Kevin

Alt history, the butterfly made me do it.

Lets see, from looking at a map it seems my visibility is about 250-300 miles. Sunrise comes, (though this is purely from an old memory as I HATE waking up that early...) would be about... 45 minutes early maybe? Of course, this is in Hawaii.

[eagl]

Actual visibility in real world conditions will probably not exceed around 40 miles from approx 10k ft.  The horizon is probably somewhere around 200-300 miles away, but atmospheric conditions rarely allow you to see anything but a hazy blur beyond 40ish miles even on a "good" day.  When visibility is nearly perfect you can probably see 80ish miles from 10k ft, however the terrain is so flat at that distance you won't get any details at all.

[Serenity]

Actual visibility in real world conditions will probably not exceed around 40 miles from approx 10k ft.  The horizon is probably somewhere around 200-300 miles away, but atmospheric conditions rarely allow you to see anything but a hazy blur beyond 40ish miles even on a "good" day.  When visibility is nearly perfect you can probably see 80ish miles from 10k ft, however the terrain is so flat at that distance you won't get any details at all.

What I did was I know from my field at 10K, I can see the far end of Maui on a good day, which is about 250 miles away. I might not see details, lol, but I can see the island.

[gunnss]

Actually I need to know if the outline of a large Island could be distinguished. Not details per say, but the sea land interface..

Regards,
Kevin

[Maverick]

It depends on the area of the world you are flying in. As Eagle said the atmosphere will blur your vision depending on how humid or particle filled the air is. If you are at 10,500 in Southern AZ you can see much much farther than you can in the Houston area. It also depends on what you are looking for. In AZ, I know I could see mountain ranges that were well over 100 miles away at altitude but smaller objects are far harder to see. Anyone used to flying outside of the dry SW is usually amazed at how easy it is to see at distances here.

Since you are looking for an island there will be humidity far in excess than in AZ. I'd say it's possible but depends on atmospheric conditions.

[Maverick]

Dupe post, sorry

[Golfer]

Actually I need to know if the outline of a large Island could be distinguished. Not details per say, but the sea land interface..

Regards,
Kevin

Again it depends.  From 47,000 feet earlier this month we could see the Turks and Caicos from over 150 miles away.  Unsing binoculars we could make out various features including hotels we'd been in before.  Down lower from 11,000 to 5000 we couldn't see our destination island (St. Maarten) until within 20 or so miles.  Compare these two photos.  The first from 9 miles up you can see fairly clearly how your visibility is not inhibited by particulates or the haze/humidity in the air.  The second from the approach you can see how visibility is down to about 20 miles or a little more from hundreds of miles.

Cell phone picture of lower quality:


Taken from a point and click digital because I didn't have mine handy:



Same day.  Same basic weather.  Different perspectives.

[Serenity]

Actually I need to know if the outline of a large Island could be distinguished. Not details per say, but the sea land interface..

Regards,
Kevin

Its pretty clear.

[bcadoo]

The formula for calculating distance to the horizon is:

where R is the radius of the Earth (R and h must be in the same units). This formula follows directly from the Pythagorean Theorem (a right triangle can be drawn with vertices at the center of the Earth, your eyes, and the point on the horizon.

[Serenity]

The formula for calculating distance to the horizon is: (Image removed from quote.)

where R is the radius of the Earth (R and h must be in the same units). This formula follows directly from the Pythagorean Theorem (a right triangle can be drawn with vertices at the center of the Earth, your eyes, and the point on the horizon.

The difference is, you might be able to see the horizon farther than detailed objects. I can see the horizon for MANY miles. I can see the BASE of the Big Island, but Maui is as far as I can see the full mountain and some details.

[gunnss]

Thanks everyone,

It is for a story, where an aircraft is flying at 10500 and needs to locate it's self after flying all night. (the aircraft has been using dead reckoning until daylight)
The land form under the ship will be distinctive, and fine detail is not needed just the land sea interface. (just enough detail for the navigator to get a fix so he can use his "Rutter" to get to Tranquebar.......)
I was just going to "hand wave" it, but decided to check if it was plausible.

Regards,
Kevin