2. Wind Effect on Aircraft
Movement
Head wind is good for
both landing and take-off Dangerous!
Reference:
Tail wind pushes the
landing aircraft-needing
longer runway to stop!
2
6. Crosswind Component
Chaos
It tends to drift the aircraft away from the
runway centerline.
Itslimiting values are prescribed by ICAO
and FAA on the basis of size of aircraft:
Small: 15kmph
Mixed: 25kmph
Large: <35kmph
6
8. 8
Runway
Orientation
For runway orientation wind data is
utilized
Wind data comprises of:
wind intensity,
duration of movement of wind
direction of movement of wind
9. 9
Typical Wind Data
Direction
Duration of Wind (%) Total
Percentage of
time wind blew
between 6.0
to 60kmph
6.0-25
kmph
25-40
kmph
40-60
kmph
N 7.4 2.7 0.2 10.3
NNE 5.7 2.1 0.3 8.1
NE 2.4 0.9 0.6 3.9
ENE 1.2 0.4 0.2 1.8
E 0.8 0.2 0 1
ESE 0.3 0.1 0 0.4
SE 4.3 2.8 0 7.1
SSE 5.5 3.2 0 8.7
S 9.7 4.6 0 14.3
SSW 6.3 3.2 0.5 10
SW 3.6 1.8 0.3 5.7
WSW 1 0.5 0.1 1.6
W 0.4 0.1 0 0.5
WNW 0.2 0.1 0 0.3
NW 5.3 1.9 0 7.2
NNW 4 1.3 0.3 5.6
Total 86.5
10. 10
Wind Data: Collection and
Application
Data collected over a period of, typically,
10 years.
Systematically arranged on Wind Rose
diagram.
11. 11
Wind Rose
Diagram
It is a compass shaped diagram
It exhibits wind direction, duration of wind
movement at different speed ranges
It shows wind speeds
It is used in working out the orientation of
runway
13. 13
Type of Wind Rose
Diagrams
Type-I Shows
Direction and
Duration of
wind ONLY
Type-II Shows
Direction,
Duration and
Speed of wind
14. Types of Wind Rose
Diagram
Type 1:
Concentric Circles: Wind DURATION
Radial Lines: DIRECTION
Type-2:
Concentric Circles represent: WIND SPEED
Numbers in Sectors: DURATION
Radial Lines: DIRECTION
16. Components of Wind Rose: Type-
I
Circles show
duration for
which wind blew
1
16
2
3
N
NNE
NE
ENE
E
ESE
SE
SSE
S
SSW
SW
WSW
W
WNW
NW
NNW
15
14
16
13
1
2
3
4
5
6
8
9
10
11
12
7
Procedure to use Wind Rose
Diagram Type-I
Step-1:
Draw concentric circles showing
wind durations
Step-2:
Divide the circles into 16
segments
Step-3:
Plot the wind duration along
respective directions and join
the points
Step-4:
Runway is oriented along the
longest line in the diagram
17. Wind Rose: Type-
I
Direction
Duration of Wind
(kmph)
N 10.3
NNE 8.1
NE 3.9
ENE 1.8
E 1
ESE 0.4
SE 7.1
SSE 8.7
S 14.3
SSW 10
SW 5.7
WSW 1.6
W 0.5
WNW 0.3
NW 7.2
NNW 5.6
0
3
6
9
12
15
N
NNE
NE
ENE
E
ESE
SE
SSE
S
SSW
SW
WSW
W
WNW
NW
NNW
17
25. Wind Rose Type-
II
25
Step-2: Mark 16 directions, each with a wind coverage area of 22.5, as
shown in the next slide
26. Wind Coverage Angle and
Area
1
2
3
4
N
5
NNE
NE
ENE
E
ESE
SE
SSE
S
SSW
SW
WSW
W
WNW
NW
NNW
22.5
26
The percentage of time in a year during which the crosswind component remained below
the specified value (See 際際滷 no. 6).
27. Wind Rose Type-
II
Step-3: Draw radial directions to show wind coverage area. This
creates
segments in which wind coverage (% time) is written
27
28. Wind Rose Type-
II
Step-4: Mark Calm Period
Calm
Period
Calm Period is
the percentage
of time during
which the wind is
blowing at a
speed less than
6.0kmph (For this
example).
Calculation on
next slide
28
29. Typical Wind
Data
Direction
Duration of Wind (%)
Total Percentage of
time wind blew
between 6.4 to
60kmph
6.0-25
kmph
25-40
kmph
40-60
kmph
N 7.4 2.7 0.2 10.3
NNE 5.7 2.1 0.3 8.1
NE 2.4 0.9 0.6 3.9
ENE 1.2 0.4 0.2 1.8
E 0.8 0.2 0 1
ESE 0.3 0.1 0 0.4
SE 4.3 2.8 0 7.1
SSE 5.5 3.2 0 8.7
S 9.7 4.6 0 14.3
SSW 6.3 3.2 0.5 10
SW 3.6 1.8 0.3 5.7
WSW 1 0.5 0.1 1.6
W 0.4 0.1 0 0.5
WNW 0.2 0.1 0 0.3
NW 5.3 1.9 0 7.2
NNW 4 1.3 0.3 5.6
Total 86.5
Calm Period = 100- 86.5 = 13.5 Percent 20
31. 31
Step-6: Determination of Runway
Orientation
Place transparent strip of width equal to the
crosswind component (at the same scale)
along a direction
Add the wind coverage percentages
superimposed by the strip + Calm period.
Then place the strip along all other directions
See This procedure in the next slides
40. 40
Final
Orientation
Wind Coverage = Sum of the percentages
under the strip for each direction + Calm
Period
The direction with maximum wind coverage
is the direction along which runway is
oriented
In case wind coverage is less than 95% -
Another runway is constructed
For busy airports, the wind coverage may be
increased to 98% or 100%.