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How do
pilots know what runway to use?
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Traffic Patterns
Just like there are traffic patterns to
get in and out of parking lots, there are traffic patterns to get
airplanes in and out of airports. The standard pattern is called a left
hand pattern. The pilot makes all the turns to the left.
Exceptions to this would be at airports were controllers would direct
traffic to the runway, or were there are obstructions or populated area
were a right hand pattern would be used. The pattern is set up so that
the pilot is landing on the runway going into
the wind. Pattern consists of three legs;
a DOWNWIND, BASE,
and FINAL. The Downwind
is the first leg, or entry leg of the
pattern. Its path is parallel to runway, but flown in
the heading opposite to the landing heading. If a pilot is
landing on runway 14, the downwind heading would be 320
degrees (140 + 180 = 320). At the landing end of the runway, the pilot
makes a left 90 degree turn to the Base
leg. This is the leg where the pilot slows down and descends the
airplane. As the plane approaches the landing end of the runway, the
pilot makes another 90 degree turn to the left. At this point, the
airplane is aligned with the runway and is on Final.
This is the leg where the pilot further descends and slows the airplane.
The pilot is also making sure that the airplane systems such as flaps
and landing gear are all down in preparation for landing.
On the compass circle, the arrow
represents the wind, with the head of the arrow pointing in the
direction the wind is blowing TO. Try to
determine the runway airplanes should use for take off and landing.
Remember to take off and land INTO wind, or
in this example, into the arrowhead.
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For taking off and
landing, an airplane must be going into the wind. This gives the
airplane better performance at a slower ground speed. Wind direction is
determined by a compass heading where
the wind is coming from.
For example, a northeast wind could be coming from a compass heading
ranging from 30 degrees to 60 degrees. Runways are numbered by the
compass heading the airplane would be going to on take off or landing.
If an airplane at Batten Field is taking off or landing on the runway
facing to the northeast, its heading would be approximately 40 degrees.
When numbering runways, only two numerals
of the compass direction are used. A runway heading 320 degrees would be
numbered 32. Runways with
headings from 10 degrees and 90 degrees have the 0 moved from the back
to the front. So a runway with a heading of 40 degrees would be numbered
04. The highest a runway
can be numbered is 36. That’s because the compass only goes to 360
degrees. Even though they have the same numerals, runway 01
is quite different from runway 10.
Runway 01 is heading northeast at 10
degrees while runway 10 is headed
a little south of east at 100
degrees.
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