|
Tips
and Tricks
Select the year for your
sunset/sunrise chart:
2009
2010
2011
2012
2013
"Night" has various definitions depending on the activity
(e.g., night landing currency, use of position lights, etc.). Consult the current FARs as your definitive source:
- 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.
Information provided from the US Naval Observatory
website. Consult and verify data with original sources before flight.
Phoenix Aviation is not responsible for errors, omissions, or changes.
Copyright © Phoenix
Aviation Incorporated 2009. All Rights Reserved.
|
