2. Wind Effect on Aircraft Movement
Head wind is good for
both landing and take-off Dangerous!
Reference: http://www.physicsclassroom.com
Tail wind pushes the
landing aircraft-needing
longer runway to stop!
2
5. V Sin(𝜽)
𝜽
Cross Wind Component
Wind Direction
Crosswind
Chaos
V
Cos(𝜽)
Head Wind/Tail Wind
Component
6. Crosswind Component Chaos
• It tends to drift the aircraft away from the runway
centerline.
• Its limiting values are prescribed by ICAO and FAA on
the basis of size of aircraft:
– Small: 15kmph
– Mixed: 25kmph
– Large: <35kmph
6
7. 7
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
8. 8
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
9. 9
Wind Data: Collection and Application
• Data collected over a period of, typically, 10
years.
• Systematically arranged on Wind Rose
diagram.
10. 10
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
11. 11
Type of Wind Rose Diagrams
Type-I Shows
Direction and
Duration of
wind ONLY
Type-II Shows
Direction,
Duration and
Speed of wind
12. 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
13. Components of Wind Rose: Type-I
Circles show
duration for
which wind blew
1
13
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
14. 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
Runway
Orientation
14
16. Wind Rose Type-II
16
Step-2: Mark 16 directions, each with a wind coverage area of 22.5, as
shown in the next slide
17. 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
17
The percentage of time in a year during which the crosswind component remained below the
specified value (See Slide no. 6).
18. Wind Rose Type-II
Step-3: Draw radial directions to show wind coverage area. This creates
segments in which wind coverage (% time) is written
18
19. 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
19
20. Typical Wind Data
Direction
Duration of Wind (%)
Total Percentage of
time wind blew
between6.4 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
22. 22
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…
31. 31
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%.