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Tips and
Tricks
Select the year for your sunset/sunrise chart:
2005
2006
2007
2008
"Night" has various definitions depending on the activity (e.g., night
landing currency, use of position lights, etc.). Consult the FARs:
- 61.57 for night landing currency (one hour after
sunset to one hour before sunrise)
- 91.209(a) for position light usage (sunset to
sunrise)
- 1.1 for definition of "night" (the end of evening civil twilight to
beginning of morning civil twilight) as it applies to VFR fuel requirements,
anti-collision light usage, etc. 91.205 and 91.209(b) also includes
information on anti-collision lights
Note: In the USA, evening civil twilight ends (night begins) about 25 - 30
minutes after official sunset, depending on latitude. Night ends with the
beginning of morning civil twilight (about 25 -30 minutes before sunrise,
depending on your latitude).
Twilight: Before sunrise and again
after sunset there are intervals of time, twilight, during which there is
natural light provided by the upper atmosphere, which does receive direct
sunlight and reflects part of it toward the Earth's surface. Some outdoor
activities may be conducted without artificial illumination during these
intervals, and it is useful to have some means to set limits beyond which a
certain activity should be assisted by artificial lighting. The major
determinants of the amount of natural light during twilight are the state of
the atmosphere generally and local weather conditions in particular.
Atmospheric conditions are best determined at the actual time and place of
events. Nevertheless, it is possible to establish useful, though necessarily
approximate, limits applicable to large classes of activities by considering
only the position of the Sun below the local horizon. Reasonable and
convenient definitions have evolved.
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.
This above definitions and the charts found in the
links are excerpted from the US Naval
Obersvatory's website and are provided solely
as a convenience. Phoenix Aviation Incorporated makes no warranty,
expressed or implied, as to the accuracy of this data; the
pilot should consult the US Naval Observatory directly or refer to official
publications as part of their preflight planning for night flights and currency
determination.
Copyright © Phoenix Aviation Incorporated 2005. All Rights Reserved.
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