"Night"

[Joshrk22]

The time between the end of evening civil twilight and the beginning of morning civil twilight, as published in the American Air Almanac, converted to local time.

"Night" means the time between the end of evening civil twilight and the beginning of morning civil twilight, as published in the American Air Almanac, converted to local time.

Can anyone tell me when civil twilight is? The AIM mentions something about 6 degrees with the sun or something, but who is going to get their protractor out to measure this? My private pilot study prep manual doesn't even tell me. Can someone enlighten me? Thanks.

 

[aucfi]

According to the U.S. Naval Observatory, civil twilight is defined to begin in the morning, and to end in the evening when the center of the Sun is geometrically 6 degrees below the horizon. This is the limit at which twilight illumination is sufficient, under good weather conditions, for terrestrial objects to be clearly distinguished; at the beginning of morning civil twilight, or end of evening civil twilight, the horizon is clearly defined and the brightest stars are visible under good atmospheric conditions in the absence of moonlight or other illumination. In the morning before the beginning of civil twilight and in the evening after the end of civil twilight, artificial illumination is normally required to carry on ordinary outdoor activities. Complete darkness, however, ends sometime prior to the beginning of morning civil twilight and begins sometime after the end of evening civil twilight. [FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Sunrise and sunset conventionally refer to the times when the upper edge of the disk of the Sun is on the horizon, considered unobstructed relative to the location of interest. Atmospheric conditions are assumed to be average, and the location is in a level region on the Earth's surface.[/FONT]

 

[midlifeflyer]

Can anyone tell me when civil twilight is? The AIM mentions something about 6 degrees with the sun or something, but who is going to get their protractor out to measure this?

These guys will:

http://aa.usno.navy.mil/data/docs/RS_OneDay.html

 

[satpak77]

dude "night time" is when its night out or "not daytime, sunrise, nor sunset"

don't make it hard than it really is

 

[A Squared]

dude "night time" is when its night out or "not daytime, sunrise, nor sunset"

don't make it hard than it really is

Ummm, duuuuude, no it is not. Night time is not everything which is "not day, sunrise nor sunset".

There actually *is* a specific legal definition of night, and your definition is wrong. You're not making it easier, you/re just making it "wronger"

 

[UndauntedFlyer]

We turn on the position lights from sunset to sunrise. We log night landings from one hour after sunset to one hour before sunrise. When is the official night used for anything? I guess it would be for logging night flight but not night landings for currency. Is that right? I really don't know. Any thoughts on this?


Also I have an official copy of the "American Air Almanac." It contains the official twilight for the definition of "night."

 

[Daytonaflyer]

Undauntedflyer,
That sounds about right to me. I use a rule of thumb: 30 minutes after official sunset equals "evening civil twilight" for logging night time. Use one hour after sunset for logging night landing currency. The only thing I use "sunset" and "sunrise" for is for 121 ops; we always had to be off the ground before sunset when departing from runways with no lights.
How can we tell if the sun is 6 degrees below the horizon anyhow? It's below the horizon, so we can't see it, lol.

 

[A Squared]

When is the official night used for anything?

91.151 night VFR fuel reserves

91.155 VFR minima for night flight

91.205 required equipment for night flight

121.590 runway lights for pax operations

just for example

 

[UndauntedFlyer]

What is really strange about all these different uses of the night definitions is that a person can be not qualified for night landings with passenges and still land 59 min past sunset when it would be pitch dark and as far as the FAR's are concerned: That was a day landing. Go figure out that one.

A Squared, thanks for your information on this too. Good work off the top of your head. .

 

[A Squared]

The only thing I use "sunset" and "sunrise" for is for 121 ops; we always had to be off the ground before sunset when departing from runways with no lights.

Do you have a source for that? I've heard that too, but haven't been able to find any support for it. I'm wondering if it's really an old wives tale or something dreamed up by some fed with too much time on his hands.

How can we tell if the sun is 6 degrees below the horizon anyhow?

By looking it up in the American AIr Almanac or the U.S. Naval observatory website.