Pre-Flight Planning resources

Pre-Flight Planning

Preparation

Daylight and darkness

Daylight and darkness AIP GEN 2.7

‘Night’ is that period between the end of the evening civil twilight and the beginning of the morning civil twilight. For all intents and purposes, first light should be construed as the beginning of civil twilight and last light as the end of civil twilight. The terms ‘sunrise’ and ‘sunset’ have no relevance when calculating daylight operating times for the VFR pilot.

To compute the beginning or end of daylight using the graphs contained in this section:

  • enter the top or bottom of the scale at the appropriate date (each line represent five-day increments)
  • move vertically up or down to the curve for the latitude of the place concerned (interpolating for intermediate latitudes if necessary)
  • move horizontally to the left or to the right and read local mean time on the vertical scale at the side
  • to convert to UTC, subtract (in E longitudes) from the LMT obtained, the time increment corresponding to the longitude of the place concerned in the Conversion of arc to time table
  • to convert to EST, add 10 hours to UTC
  • to convert to CST, add 9.5 hours to UTC and
  • to convert to WST, add 8 hours to UTC.

When using these graphs, note that the parameters used in compiling them do not include the nature of the terrain surrounding a location, or the presence of other than a cloudless sky and unlimited visibility at that location.

Consequently, cloud cover, poor visibility or high terrain to the west of an aerodrome will cause daylight to end at a time earlier than that extracted from the appropriate graph. Allowance should be made for these factors when planning a flight having an ETA near the time of last light.

NAIPS automatically computes first light and last light. This information can be provided through pilot access, as part of a telephone briefing, or from Flightwatch.

Local time

Local time in Australia falls into three separate zones:

EST
UTC + 10 hours
New South Wales (except the Broken Hill area), Queensland, Victoria, Tasmania and the Australian Capital Territory
CST
UTC + 9.5 hours
South Australia, the Northern Territory and the Broken Hill area
WST
UTC + 8 hours
Western Australia

However, certain states introduce local summer time each year between October of that year and March of the following year, which adds an additional hour to the local time applicable in that state

A notice to airmen (NOTAM) or aeronautical information publication (AIP) supplements will be issued detailing revised hours of operation for those aeronautical facilities affected by local time changes during periods of State Summer Time and which do not have such hours publicised in AIP.

Time of last light AIP GEN 2.7

Worked example

Find the time of last light for a location at S36 09.0 E144 46.0 on 20 November.

Solution

Use the Time of last light April to September chart (see page 2.27 top) and Arc to time conversion table (page 2.29):

  1. Using the Time of last light chart, enter at 20 November and follow downward until reaching latitude 36° (by interpolation) then straight across to read off Local Mean Time (LMT) = 1919.
  2. To convert to UTC, using the Arc to time conversion table, find longitude 144° = 9h 36m.
  3. Add the increment corresponding to 46’ in the right hand column = 3’ 04” + 0936 = 0939.
  4. Subtract the arc to time from the LMT to give the time of last light in UTC: 1919-0939 = 0940 UTC

Location
Echuca
Date
20 November
Lat/Long
S36 09.0 E144 46.0

Time of first light April to September

Time of first light October to March

Time of last light April to September

Time of last light October to March

Arc to time conversion AIP GEN 2.7

Degrees

Minutes

Long deg

Time

Long deg

Time

Long min

Time

Long min

Time

Hr

Min

Hr

Min

Min

Sec

Min

Sec

110

7

20

135

9

00

0

0

00

30

2

00

111

7

24

136

9

04

1

0

04

31

2

04

112

7

28

137

9

08

2

0

08

32

2

08

113

7

32

138

9

12

3

0

12

33

2

12

114

7

36

139

9

16

4

0

16

34

2

16

115

7

40

140

9

20

5

0

20

35

2

20

116

7

44

141

9

24

6

0

24

36

2

24

117

7

48

142

9

28

7

0

28

37

2

28

118

7

52

143

9

32

8

0

32

38

2

32

119

7

56

144

9

36

9

0

36

39

2

36

120

8

00

145

9

40

10

0

40

40

2

40

121

8

04

146

9

44

11

0

44

41

2

44

122

8

08

147

9

48

12

0

48

42

2

48

123

8

12

148

9

52

13

0

52

43

2

52

124

8

16

149

9

56

14

0

56

44

2

56

125

8

20

150

10

00

15

1

00

45

3

00

126

8

24

151

10

04

16

1

04

46

3

04

127

8

28

152

10

08

17

1

08

47

3

08

128

8

32

153

10

12

18

1

12

48

3

12

129

8

36

154

10

16

19

1

16

49

3

16

130

8

40

155

10

20

20

1

20

50

3

20

131

8

44

156

10

24

21

1

24

51

3

24

132

8

48

157

10

28

22

1

28

52

3

28

133

8

52

158

10

32

23

1

32

53

3

32

134

8

56

159

10

36

24

1

36

54

3

36

25

1

40

55

3

40

26

1

44

56

3

44

27

1

48

57

3

48

28

1

52

58

3

52

29

1

56

59

3

56

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