Definition of night time

hammerhat

hammerhat

Well-Known Member
If an aircraft is approved for day VFR only and has position lights when does the night start for this aircraft? IOW can it be operated between the sunset and the end of civil twilight?
 
91.1

Night means the time between the end of evening civil twilight and the beginning of morning civil twilight, as published in the Air Almanac, converted to local time.
 
Even though not technically night until end of civil twilight, position lights would still need to be on after sunset.
 
BarbieDreamPilot said:
91.1

Night means the time between the end of evening civil twilight and the beginning of morning civil twilight, as published in the Air Almanac, converted to local time.
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Sweet. So how do you measure how far below the sun is below the horizon?

I honestly think of these things as a "WTF, WHO KNOWS?! It's dark out, I'm logging it as night."
 
mshunter said:
Sweet. So how do you measure how far below the sun is below the horizon?

I honestly think of these things as a "WTF, WHO KNOWS?! It's dark out, I'm logging it as night."
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As you quoted:

... as published in the Air Almanac, converted to local time...
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Sunset and Sunrise have an exact time each day, and the geometric center of the sun positioned 6° below the horizon (end/beginning of civil twilight) has an exact time, as well. We've kinda had that established for hundreds of years, and built an entire civilization with reference to it. It's really not that hand-wavey.

Really, log what you want—I really don't care—but if you want the actual answers, they're out there and clearly defined, and I, for one, use them.

-Fox
 
Acrofox said:
As you quoted:



Sunset and Sunrise have an exact time each day, and the geometric center of the sun positioned 6° below the horizon (end/beginning of civil twilight) has an exact time, as well. We've kinda had that established for hundreds of years, and built an entire civilization with reference to it. It's really not that hand-wavey.

Really, log what you want—I really don't care—but if you want the actual answers, they're out there and clearly defined, and I, for one, use them.

-Fox
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Yeah, and I believe that you go to an almanac every time you fill out your log book.
 
mshunter said:
Yeah, and I believe that you go to an almanac every time you fill out your log book.
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Why "every time"?
  • If you fly nights regularly, you might only need to do it once to get a general idea and accurately guesstimate after that.
  • If you only do it once in a while, what's the big deal with an extra 60 seconds to check*, especially if you are getting online weather briefings. (I haven't even checked mine but I wouldn't be surprised if some EFB apps do it and I'd bet one can download one that will.)
  • It might be so obvious you don't need to. Local area or the same destination regularly, one gets to know when it gets dark and about what time the sun sets - takeoff and landing after tha, I wound;t bother checking.
  • If it's one of those typical night flights when you take off when it is still light and you haven't done and don't expect to do a night takeoff before daylight in the morning, you wouldn't bother since your night landing doesn't really count for currency anyway.
  • If it's an intentional night currency flight, that 60 seconds takes place hours or even days before.
  • If it's not even dark, why would you bother to check?
[* I'm being very liberal on the amount of time. It's pretty easy to check http://aa.usno.navy.mil/data/docs/RS_OneDay.php]
 
MidlifeFlyer said:
Why "every time"?
  • If you fly nights regularly, you might only need to do it once to get a general idea and accurately guesstimate after that.
  • If you only do it once in a while, what's the big deal with an extra 60 seconds to check*, especially if you are getting online weather briefings. (I haven't even checked mine but I wouldn't be surprised if some EFB apps do it and I'd bet one can download one that will.)
  • It might be so obvious you don't need to. Local area or the same destination regularly, one gets to know when it gets dark and about what time the sun sets - takeoff and landing after tha, I wound;t bother checking.
  • If it's one of those typical night flights when you take off when it is still light and you haven't done and don't expect to do a night takeoff before daylight in the morning, you wouldn't bother since your night landing doesn't really count for currency anyway.
  • If it's an intentional night currency flight, that 60 seconds takes place hours or even days before.
  • If it's not even dark, why would you bother to check?
[* I'm being very liberal on the amount of time. It's pretty easy to check http://aa.usno.navy.mil/data/docs/RS_OneDay.php]
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Every time because I do my logbook at the end of every month (or as close to it as possible).
 
MidlifeFlyer said:
You are complaining about checking once a month while sitting around with a beer? :fury:
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No. I'm stating who the eff is that concerned about it that they bother to check. The only thing that it matters for is currency after you get your certificates. There is a 99% probability that it is not going to be close when it comes to logging landings. Quit splitting hairs.
 
mshunter said:
No. I'm stating who the eff is that concerned about it that they bother to check. The only thing that it matters for is currency after you get your certificates. There is a 99% probability that it is not going to be close when it comes to logging landings. Quit splitting hairs.
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If you look at my earlier post, you will see I pretty much agree with you (unless you think the only choice is between checking everything and nothing). I think you'll also agree night passenger currency is a currency matter. If that's the issue, I don't see any reason not to check that 1% of the time when it is close.

Logging night time for the sake of logging night time? No currency issue there and no real reason to track it at all once all night flight requirements are met for the next certificate or rating.

.
 
MidlifeFlyer said:
If you look at my earlier post, you will see I pretty much agree with you (unless you think the only choice is between checking everything and nothing). I think you'll also agree night passenger currency is a currency matter. If that's the issue, I don't see any reason not to check that 1% of the time when it is close.

Logging night time for the sake of logging night time? No currency issue there and no real reason to track it at all once all night flight requirements are met for the next certificate or rating.

.
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I never really disagreed with you though. I win! :)
:stir:
 
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