night definition
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night definition
Hello All
Can someone give a answer to what is night, as have been told by CASA there is no definition.
EG Day is from 0001 to 2359.
But what is night.
Have fun
Can someone give a answer to what is night, as have been told by CASA there is no definition.
EG Day is from 0001 to 2359.
But what is night.
Have fun
In what context?
Day, as in Day VFR, is surely between first light and last light (or whatever the flaming terminology is in use in Aus). Night must be the complimentary set of day, surely?
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CASA on the website under info for logbooks (or AIC H10/99, if it is still current)
" 'night flying' - means the flight time which accrues during the period between the end of evening civil twilight and the beginning of morning civil twilight."
I am not sure how particular with a definition of night you wish to be?
" 'night flying' - means the flight time which accrues during the period between the end of evening civil twilight and the beginning of morning civil twilight."
I am not sure how particular with a definition of night you wish to be?
Oh for **** sake! 
It's in the AIP!
DAY: That period of time from the beginning of morning civil twilight to the end of evening civil twilight
NIGHT: That period of time between the end of evening civil twilight to the beginning of morning civil twilight
http://www.airservicesaustralia.com/...n/2_2_1-22.pdf
Now, pay attention - civil twilight is an astronomical event which begins in the MORNING when the center of the Sun is less than 6 degrees below the horizon (the point of civil dawn), and ends at sunrise. Evening civil twilight begins at sunset and ends when the center of the Sun is more than 6 degrees below the horizon (the point of civil dusk).
Sunrise is the instant in the morning under ideal meteorological conditions, with standard refraction of the sun's rays, when the upper edge of the sun's disk is coincident with an ideal horizon. Sunset is the instant in the evening under ideal meteorological conditions, with standard refraction of the sun's rays, when the upper edge of the sun's disk is coincident with an ideal horizon.
Sunrise and sunset both are completley different times to civil twilight.
There is also nautical twilight and astronomical twilight but they have noting to do with the AUS AIP definition.
Here's what I use at work:
http://www.ga.gov.au/geodesy/astro/sunrise.jsp
And here's a list of definitions:
http://www.ga.gov.au/geodesy/astro/definiti.jsp#SUN
Here it is for today:
SYDNEY (KINGSFORD-SMITH) AIRPORT Lat=-33°56'00" Long=+151°10'00"
TIMES OF CIVIL TWILIGHT
(for ideal horizon & meteorological conditions)
Time zone: +10.00 hours
20/09/2007 Rise 0524 Set 1815
Tomorrow will be different.
It's in the AIP!
DAY: That period of time from the beginning of morning civil twilight to the end of evening civil twilight
NIGHT: That period of time between the end of evening civil twilight to the beginning of morning civil twilight
http://www.airservicesaustralia.com/...n/2_2_1-22.pdf
Now, pay attention - civil twilight is an astronomical event which begins in the MORNING when the center of the Sun is less than 6 degrees below the horizon (the point of civil dawn), and ends at sunrise. Evening civil twilight begins at sunset and ends when the center of the Sun is more than 6 degrees below the horizon (the point of civil dusk).
Sunrise is the instant in the morning under ideal meteorological conditions, with standard refraction of the sun's rays, when the upper edge of the sun's disk is coincident with an ideal horizon. Sunset is the instant in the evening under ideal meteorological conditions, with standard refraction of the sun's rays, when the upper edge of the sun's disk is coincident with an ideal horizon.
Sunrise and sunset both are completley different times to civil twilight.
There is also nautical twilight and astronomical twilight but they have noting to do with the AUS AIP definition.
Here's what I use at work:
http://www.ga.gov.au/geodesy/astro/sunrise.jsp
And here's a list of definitions:
http://www.ga.gov.au/geodesy/astro/definiti.jsp#SUN
Here it is for today:
SYDNEY (KINGSFORD-SMITH) AIRPORT Lat=-33°56'00" Long=+151°10'00"
TIMES OF CIVIL TWILIGHT
(for ideal horizon & meteorological conditions)
Time zone: +10.00 hours
20/09/2007 Rise 0524 Set 1815
Tomorrow will be different.
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Geez air med you were on to this quick!
Guys, what air med is referring to, isnt what goes in the log book.
What he (and a few of us) is trying to find out is with regards to rostering. Certain operators, such as the RFDS, require guys to do shift work, ie day and night. Day shift generally being 0600 - 1800 and night 1800 - 0600.
Under the CAO 48 dispo, required time off between shifts is often referenced to local nights eg:
" In any consecutive 14 nights, a flight crew member shall have either -
a. 2 periods free of all duty, each of which is a minimum of 36 consecutive hours duration and comprising 2 local nights; or
b. 1 period free of all duty, comprising a minimum of 60 consecutive hours and three consecutive nights;"
Most required time off mentions the period 2200 - 0600 but nowhere is this defined as "night", especially "local night".
Now when a "day" is referred to as "the period between local midnight and the subsequent local midnight", then what, as air med meant when he started this topic, is a night?
Guys, what air med is referring to, isnt what goes in the log book.
What he (and a few of us) is trying to find out is with regards to rostering. Certain operators, such as the RFDS, require guys to do shift work, ie day and night. Day shift generally being 0600 - 1800 and night 1800 - 0600.
Under the CAO 48 dispo, required time off between shifts is often referenced to local nights eg:
" In any consecutive 14 nights, a flight crew member shall have either -
a. 2 periods free of all duty, each of which is a minimum of 36 consecutive hours duration and comprising 2 local nights; or
b. 1 period free of all duty, comprising a minimum of 60 consecutive hours and three consecutive nights;"
Most required time off mentions the period 2200 - 0600 but nowhere is this defined as "night", especially "local night".
Now when a "day" is referred to as "the period between local midnight and the subsequent local midnight", then what, as air med meant when he started this topic, is a night?
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Astronomical night occurs when the sun is 18 degrees below the horizon...
as have been told by CASA there is no definition.
You are correct in what you state, but if a day is stated to be from 0001 to 2359, then how do you determine night, there is no answer
Day is that period of time from the beginning of morning civil twilight to the end of evening civil twilight.
Civil twilight begins in the morning at civil dawn and ends at sunrise.
Evening civil twilight begins at sunset and ends at dusk.
That between civil dawn and civil dusk is day. The rest (apart from the twilight) is night.
For our purposes, it is defined in the AIP however that definition is reliant upon another definition - see above
What you are describing (ie: from 0001 to 2359) is merely a measurement of time being a period of 24 hours which corresponds to a rotation of the earth on its axis. That's it, nothing else.
The Oxford Dictionary which is used by the Australian courts offers a definition, amongst others, of "day" as the time between sunrise and sunset,
which in turn is defined as that period between dawn and dusk.
Just land 10 mins before last light and have a beer!
Last edited by Atlas Shrugged; 20th Sep 2007 at 08:58.
HH,
Not quite. Astronomical twilight is the time when the center of the sun is more than 12 degrees below the ideal horizon but not more than 18 degrees - for the measurement an "ideal horizon" 90 degrees from the zenith is used.
The time it takes the sun to travel that 6 degrees is astronomical twilight.
The levels (or altitudes, if you like) of the sun below the horizon are "true geometric" altitudes which means we ignore a number of things but mainly refraction by the atmosphere having an effect on the observed position of the sun.
PS: I just re-read you post and realised you said "astronomical night" rather than "astronomical twilight"
"Astronomical night" does not exist. There ain't no such thing
Not quite. Astronomical twilight is the time when the center of the sun is more than 12 degrees below the ideal horizon but not more than 18 degrees - for the measurement an "ideal horizon" 90 degrees from the zenith is used.
The time it takes the sun to travel that 6 degrees is astronomical twilight.
The levels (or altitudes, if you like) of the sun below the horizon are "true geometric" altitudes which means we ignore a number of things but mainly refraction by the atmosphere having an effect on the observed position of the sun.
PS: I just re-read you post and realised you said "astronomical night" rather than "astronomical twilight"
"Astronomical night" does not exist. There ain't no such thing
Last edited by Atlas Shrugged; 20th Sep 2007 at 08:39. Reason: to add a PS
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Rubbery???
Are CASA making rubbery rules that no-one can understand again????? That they cannot define themselves???
I remember asking a senior CASA bloke to clarify something, and he said "legal opinion is divided about that"
If the rules are not clear and understandable, they are not complying with the directions they recieved from the minister.
I remember asking a senior CASA bloke to clarify something, and he said "legal opinion is divided about that"
If the rules are not clear and understandable, they are not complying with the directions they recieved from the minister.
Bushy,
I don't really think they are. At the end of the day, it will be decided by the courts. CASA only make the rules. If a precedent has already been set then that's it. If no precedent, then the matter under review will set one, which will become the basis of future deliberations. The problem is that after countless centuries of law, there are so many of them and the courts continue inventing (oops, should have said evolving
) new and interesting laws every day - to suit who is anyone's guess ??
I don't really think they are. At the end of the day, it will be decided by the courts. CASA only make the rules. If a precedent has already been set then that's it. If no precedent, then the matter under review will set one, which will become the basis of future deliberations. The problem is that after countless centuries of law, there are so many of them and the courts continue inventing (oops, should have said evolving
) new and interesting laws every day - to suit who is anyone's guess ??
Sprucegoose
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"Astronomical night" does not exist. There ain't no such thing
PS: I can find many references to atronomical night on google, sadly none from a reputable source...
Oh dear
The education system obviously no longer imparts upon school students, or at least upon some of the denizens of the aviation industry, the difference between:
‘day’ as an environmental phenomenon (e.g. ‘Make sure you only fly when it’s day, Philomena’)
and
‘day’ as a period of time (e.g. ‘Take your medicine at least 3 times a day, Philomena’).
The education system obviously no longer imparts upon school students, or at least upon some of the denizens of the aviation industry, the difference between:
‘day’ as an environmental phenomenon (e.g. ‘Make sure you only fly when it’s day, Philomena’)
and
‘day’ as a period of time (e.g. ‘Take your medicine at least 3 times a day, Philomena’).
