RUNWAY
According to the International
Civil Aviation Organization (ICAO)
a runway is a
"defined rectangular area on a land aerodrome prepared
for the landing and takeoff of aircraft".
NAMING THE
RUNWAY
Runways are named by a
number between 01 and 36, which is generally the magnetic azimuth of the runway’s heading in decadegrees:
a runway numbered 09 points
east (90°), runway 18
is south (180°), runway 27
points west (270°) and runway 36
points to the north (360° rather than 0°). When taking off from or landing on runway 09, a plane would
be heading 90° (east).A runway can normally be used in both directions, and is
named for each direction separately: e.g., "runway 33" in one
direction is "runway 15" when used in the other. The two numbers
always differ by 18 (= 180°).
RUNWAY
DESIGNATION
Runway
designations change over time because the magnetic poles slowly
drift on the Earth's surface and the magnetic bearing will change. Depending on the airport location and how
much drift takes place, it may be necessary over time to change the runway
designation. As runways are designated with headings rounded to the nearest
10 degrees, this will affect some runways more than
others. For example, if the magnetic heading of a runway is 233 degrees,
it would be designated Runway 23. If the magnetic heading changed
downwards by 5 degrees to 228, the Runway would still be Runway 23.
If on the other hand the original magnetic heading was 226 (Runway 23),
and the heading decreased by only 2 degrees to 224, the runway should
become Runway 22.
RUNWAY LENGTH
- A runway of at least 6,000 ft. (1,829 m) in length is usually adequate for aircraft weights below approximately 200,000 lb. (90,718 kg).
- Larger aircraft including wide bodies will usually require at least 8,000 ft. (2,438 m) at sea level and somewhat more at higher altitude airports.
- International wide body flights, which carry substantial amount fuel are therefore heavier may also have landing requirement of 10,000 ft. (3,000 m).
- At sea level 10,000 ft (3,000 m) can be consider an adequate length to land virtually any aircraft.
RUNWAY MARKINGS
- There are runway markings and signs on most large runways. Larger runways have a distance remaining sign (black box with white numbers). This sign uses a single number to indicate the thousands of feet remaining, so 7 will indicate 7,000 ft (2,134 m) remaining. The runway threshold is marked by a line of green lights.
- Runway surface marking are white color strips which h is in the center white broken strips which indicates the center on the runway and provides alignment guidance for aircraft.
- Displaced thresholds may be used for taxiing, takeoff, and landing roll out, but
not for touchdown. A displaced threshold often exists because obstacles
just before the runway, runway strength, or noise restrictions may make
the beginning section of runway unsuitable for landings. It is marked with white paint
arrows that lead up to the beginning of the landing portion of the runway.
- Blast pads, also known as overrun areas or stop ways, are often
constructed just before the start of a runway where jet blast produced
by large planes during the takeoff roll could otherwise erode the ground
and eventually damage the runway. Overrun areas are also constructed at the end
of runways as emergency space to slowly stop planes that overrun the
runway on a landing gone wrong, or to slowly stop a plane on a rejected takeoff or a takeoff gone wrong. Blast
pads are often not as strong as the main paved surface of the runway and
are marked with yellow chevrons. Planes are
not allowed to taxi, take off or land on blast pads, except in an
emergency.
RUNWAY LIGHTNING
Runway lighting is used at airports that allow night landings.
Seen from the air, runway lights form an outline of the runway. A particular
runway may have some or all of the following:
- Runway end identifier
lights (REIL) – unidirectional (facing
approach direction) or omni directional pair of synchronized flashing lights
installed at the runway threshold, one on each side.
- Runway end lights – a pair of four lights on each side of the runway on
precision instrument runways, these lights extend along the full width of
the runway. These lights show green when viewed by approaching aircraft
and red when seen from the runway.
- Runway edge lights – white elevated lights that run the length of the runway on
either side. On precision instrument runways, the edge-lighting becomes
yellow in the last 2,000 ft (610 m) of the runway, or last third
of the runway, whichever is less. Taxiways are differentiated by being
bordered by blue lights, or by having green center lights, depending on
the width of the taxiway, and the complexity of the taxi pattern.
- Runway center line lighting system (RCLS) – lights embedded into the surface of the runway at
50 ft (15 m) intervals along the runway center-line on some
precision instrument runways. White except the last 900 m
(3,000 ft): alternate white and red for next 600 m
(1,969 ft) and red for last 300 m (984 ft).
- Touchdown zone lights (TDZL) – rows of white light bars (with three in each row) at
30 or 60 m (98 or 197 ft) intervals on either side of the center line for 900 m (3,000 ft).
- Taxiway center line lead-off
lights – installed along lead-off markings, alternate green and
yellow lights embedded into the runway pavement. It starts with green
light at about the runway center line to the position of first center line light
beyond the Hold-Short markings on the taxiway.
- Taxiway center line lead-on lights – installed the same way as taxiway center line lead-off
Lights, but directing airplane traffic in the opposite direction.
- Land and hold short lights – a row of white pulsating lights installed across the runway
to indicate hold short position on some runways that are facilitating land and
hold short operations (LAHSO).
- Approach lighting system (ALS) – a lighting system installed on the approach end of an
airport runway and consists of a series of light-bars, strobe lights, or a combination of the two that extends
outward from the runway end.
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