Date: October 02, 2007 05:07PM
"Als Nacht gilt der Zeitraum zwischen einer halben Stunde nach Sonnenuntergang und einer halben Stunde vor Sonnenaufgang. "
seems to mean (according to automatic translation):
"As a night the period is considered between a half hour after sunset and a half hour before sunrise."
It's almost the same in France:
"Nuit : Période pendant laquelle le centre du disque solaire se trouve à plus de 6 degrés en dessous de l'horizon.
Il est admis que :
- pour des latitudes comprises entre 30° et 60° la nuit commence 30 minutes après le coucher du soleil et se termine 30 minutes avant le lever du soleil;
- pour des latitudes inférieures ou égales à 30° la nuit commence 15 minutes après le coucher du soleil et se termine 16 minutes avant le lever du soleil."
Which means in english (with automatic translation):
"Night: Period during which the center of the solar disc is with more than 6 degrees in lower part of the horizon.
It is allowed that:
- for latitudes ranging between 30° and 60° the night begins 30 minutes after laying down it sun and finishes 30 minutes before the rising of the sun;
- for latitudes lower or equal to 30° the night begins 15 minutes after laying down it sun and finishes 16 minutes before the rising of the sun."
In sweden, they talk about the distance to see a light... (I don't accurately).
So, there are a lot of way to say if you are in the night or not, but, when we talk about sunrise, sunset, aeronautic day, aeronautic night, there is only one definition at each time. The definition (which is in the ICAO rules) are given by scientifics like astrophysicists.
When we have changed in OF the way to compute aeronautic day and aeronautic night, (from release 1.1 to 1.2) there was a controversy about that. Some french pilots (and instructors) said that our computations where wrong, because it was +-30 minutes. So, we published a explanation about that in our FAQ (only in french, sorry, I will translate it in english, some times). The conclusion of our FAQ is the following:
- computed and displayed values are the right ones, according to the definitions of each word
- if pilots want to use +-30 minutes, they just have to take sunrise and sunset and to add or sub 30 minutes ;-)