Distance To The Horizon

Geico266

Geico266

Touchdown! Greaser!
Joined
Jun 15, 2008
Messages
19,136
Location
Husker Nation, NE
Display Name
Display name:
Geico
Ever wonder how far is the horizon when flying?


AGL / Horizon Mile Away

1,000 = 38.71

2,000 = 54.76

3,000 = 66.10

4,000 = 77.44

5,000 = 85.45925

6,000 = 93.4785

7,000 = 101.49775

8,000 = 109.517

9,000 = 117.53625
 
Geico266 said:
Ever wonder how far is the horizon when flying?


AGL / Horizon Mile Away

1,000 = 38.71

2,000 = 54.76

3,000 = 66.10

4,000 = 77.44

5,000 = 85.45925

6,000 = 93.4785

7,000 = 101.49775

8,000 = 109.517

9,000 = 117.53625
Click to expand...

What if you are 10000'..............












..........above Everest?
 
EdFred said:
What if you are 10000'..............

..........above Everest?
Click to expand...

Figure 29,029+10,000=39,029. Square root of that is 197.6 multiply that by 1.17 gives us a horizon at 231.2 nautical miles given a smooth sphere.

Horizon in NM = 1.17*Square root of height of eye in feet.
 
Last edited:
It's not a hard calculation.

To get those numbers, you have to ignore refraction, which is a much bigger effect near the horizon than you might think. It's good for more than a degree.

Please don't overdo the decimals. You can't measure 100+ miles down to 1/100,000 mile (about 1/16 inch) with conventional equipment.
 
Henning said:
Figure 29,029+10,000=39,029. Square root of that is 197.6 multiply that by 1.17 gives us a horizon at 231.2 nautical miles given a smooth sphere.

Horizon in NM = 1.17*Square root of height of eye in feet.
Click to expand...

I know this is your ballywick, Henning, but I remember a short course on the use of airborne weather radar (video, by Archie Trammel) in which we were taught a good rule of thumb for the horizon distance is to multiply the altitude (in ten of thousands) by 4, IE, 30,000ft. X 4 = roughly 120 miles to the horizon. Is that not correct?
 
Nope.

The precise geometrical calculation is

d = sqrt(h*(2R+h))

where R is the radius of the Earth and all the distances are in nm.

If the altitude h is much less than the radius of the earth (seems like a good approximation for an airplane...), h**2 is small and you get

d = sqrt(2*R*h).

So, the square root dependence is correct. Linear dependence is not unless you're thousands of miles above the surface.
 
j1b3h0 said:
I know this is your ballywick, Henning, but I remember a short course on the use of airborne weather radar (video, by Archie Trammel) in which we were taught a good rule of thumb for the horizon distance is to multiply the altitude (in ten of thousands) by 4, IE, 30,000ft. X 4 = roughly 120 miles to the horizon. Is that not correct?
Click to expand...

All I remember from Celestial is the above formula and I will allow it is likely not the most precise formula, but it will work you a 3-5nm accuracy fix; although most everybody I know including me just gets the correction factor from the Nautical Almanac table.
 
Henning said:
All I remember from Celestial is the above formula and I will allow it is likely not the most precise formula, but it will work you a 3-5nm accuracy fix; although most everybody I know including me just gets the correction factor from the Nautical Almanac table.
Click to expand...

Feel free to use my chart. :D

;)
 
pmanton said:
The horizon is an infinite distance away. No matter how long you fly you never reach it.
Click to expand...

Incorrect! The horizon is directly at the bottom of the glide from the last drop of fuel onboard. Let the fuel run out and you will meet the horizon in an unplanned place lol.
 
Has anyone had the illusion that the earth is a bowl with the plane even with the rim of the bowl (horizon) and the bottom of the bowl directly below the plane

I understand the desert southwest native Americans had that illusion when standing on top of a mesa. It was as if they were standing on a pillar rising to the rim of the bowl.

It has happened to me only once, but was very vivid.
 
tinerj said:
Has anyone had the illusion that the earth is a bowl with the plane even with the rim of the bowl (horizon) and the bottom of the bowl directly below the plane

I understand the desert southwest native Americans had that illusion when standing on top of a mesa. It was as if they were standing on a pillar rising to the rim of the bowl.

It has happened to me only once, but was very vivid.
Click to expand...

Were you eating mushrooms or peyote? :rofl:
 
I can see for miles and miles and miles . ..

Not on most days in Michigan.
 
tinerj said:
Has anyone had the illusion that the earth is a bowl with the plane even with the rim of the bowl (horizon) and the bottom of the bowl directly below the plane

I understand the desert southwest native Americans had that illusion when standing on top of a mesa. It was as if they were standing on a pillar rising to the rim of the bowl.

It has happened to me only once, but was very vivid.
Click to expand...
I used to use a 21mm lens to create that effect.
 
EdFred said:
I didn't even notice the URL and was like, ok...not quite buying it, then I read the first sentence, and was like wtf???
Click to expand...

That site is hilarious. Made my day....
 
Last edited:
I took a geography class once and the prof said he always wanted to join the Flat Earth Society. He said it would be fun to explain that on a resume - but not THAT fun.
 
Matthew said:
You guys...


The viewing distance is simply limited by air density:
http://theflatearthsociety.org/wiki/index.php?title=Viewing_Distance
Click to expand...

What is really sad is that there ARE those who buy into this. I had a neighbor when I was stationed in Corpus Christi who was a complete loon. The Earth was flat, man never went to the moon, the world will end in X number of days because his Pentacostal preacher said so, etc etc.

I asked about the pictures of Earth from space, (faked).....dinosaur bones....(less than 6,000 years old, scientists were wrong).....I asked why then if I plotted a course using a Great Circle route, (lost about 50 minutes of my life trying to explain this term) I would find my destination every time.

His answer? Government compasses were all screwed up. :rofl:
 
I was amazed at how far out I could see the ocean when I flew south for the first time.
 
You must log in or register to reply here.
Back
Top