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Airport,
Taxiway, and Runway Lights Explained
BY SARINA HOUSTON
If you've been to any
major airport at night, you've probably noticed that there are a lot of
different kinds of lights, ranging from flashing white or yellow to steady red,
green, and blue.
Airport lighting is
essential for aircraft operating at night.
Airport lights can be
divided into different types: General airport lighting, taxiway lighting,
runway lighting, and visual glideslope indicators.
General Airport
Lighting
This first type of
lighting consists of the can't-miss-it airport beacon and any warning lights on
top of towers, buildings, and construction equipment.
The airport beacon is
a large, powerful, rotating light that's highly visible from miles away.
Public-use airport
beacons rotate green and white. Military airports rotate green and white but
have two white lights for each green light, thus differentiating themselves
from civilian airports.
Heliports rotate
between green, white, and yellow lights.
Pilots can easily
identify an airport at night from its beacon, making it one of the easiest
checkpoints for pilots when navigating on a night flight.
Air traffic
controllers may turn the beacon on and off as necessary, or it may be set on a
timer.
Airport buildings,
towers, and other tall equipment on the field will have a small, steady red
beacon on top of them to aid in collision avoidance for low-flying aircraft.
Taxiway Lights
There are four types
of lights on the taxiway, a path for airplanes heading to or coming from a
runway.
Taxiway edge lights: These lights are
blue in color and line the taxiway. Airports often have green taxiway
centerline lights as well.
Clearance bar lights: Set inside the taxiway,
these lights are steady and yellow and are meant to increase the visibility of
a hold position line or a taxiway intersection at night.
Stop bar lights: These in-pavement
lights are steady red and extend across the taxiway at a hold short line, the
area where a taxiway meets the runway. They are meant to prevent a pilot from
leaving the taxiway when their plane would be in danger of causing a collision
on a runway. Once a pilot is cleared onto the runway, the air traffic
controller will turn off the stop bar lights.
Runway guard lights: A pair of two
flashing yellow lights that are positioned at each side of the taxiway at the
hold short line, the runway guard lights are meant to draw attention to the
hold short line.
Runway Lights
There are five different
kinds of runway lights.
Runway end identifier
lights:
This pair of white flashing lights, one on each side of the approach end of the
runway, helps distinguish the runway from the taxiway at night.
Runway edge lights (HIRLs/MIRLs/LIRLs):
On the edges of instrument runways (those equipped with visual and electronic
navigational aids and for which a straight-in landing minimum altitude has been
approved), these steady lights start out white and change to yellow during the
last 2,000 feet, or half the runway length, whichever is less.
Then they change to red as the aircraft
reaches the end of the runway. They can be high intensity (HIRLs), medium
iintensity (MIRLs), or low intensity (LIRLs).
Runway centerline
lighting system
(RCLS): On some precision runways — those for which there is both horizontal
and vertical guidance — an RCLS is installed, with white lights spaced at
50-foot intervals on the centerline of the runway.
With 3,000 feet remaining, the white lights
change to alternating white and red. During the last 1,000 feet, the lights are
all red.
Touchdown zone lights: These steady white
lights are placed in two rows next to the centerline, starting at 100 feet and
extending to the midpoint of the runway, or 3,000 feet beyond the threshold
(the designated ideal landing area), whichever is less.
Land and hold short
lights:
When land and hold short operations (LAHSO) are in effect, flashing white
lights may be seen across the runway at the hold short line.
During LAHSO, air traffic control may require
a pilot who has just landed to hold their position to keep clear an
intersecting runway or taxiway or some other designated point on a runway.
Runway status lights: This group of
lights includes runway entrance lights, the takeoff hold light array, runway intersection
lights, and the final approach runway occupancy signal.
These lights assist in informing pilots and
ground vehicle operators when it's safe to enter or cross a runway. They work
in conjunction with surveillance systems (like ADS-B) and are fully automated.
Visual Glide Slope
Indicators
Visual glide slope
indicators are meant to give pilots a visual guide during their descent to help
maintain a stabilized approach.
They come in two
types, visual approach slope indicators (VASIs) and precision approach path
indicators (PAPIs), each of which has multiple types of arrangements and both
of which give pilots a good idea whether they're on the glide path for a stable
approach.
VASIs: These are bars of
lights on the side of the runway that give pilots a visual indication of
whether their aircraft is too high or too low on the approach.
VASIs can be made up of 2, 4, 6, 12, or 16
lights, are commonly located on two bars — near and far — and provide an
indication for a 3-degree glide slope, the typical approach path for a landing.
In a common two-bar VASI system, a pilot
should see two red lights on the higher, far bars and two white lights on the
lower, near bars.
If all lights on the near and far bars are
red, the pilot is too low. If all lights on the near and far bars are white,
the pilot is too high. Pilots use the saying "red over white, you're all
right" regarding VASIs.
PAPIs: These sets of lights
are arranged horizontally and typically include four lights that can be red or
white, depending on where the aircraft is in the glide slope.
A PAPI system is usually located on the left
side of the runway. When all four lights are white, the aircraft is too high.
As the plane, descends onto the glide path,
the lights on the right side will begin to turn red.
When an aircraft is on the precise glide
path, the two left lights will be white and the two right lights will be red.
When three or more lights are red, the aircraft is too low.
Sarina Houston
Commercial Pilot and
Flight Instructor with Single and Multi-Engine Instrument ratings
Worked for
Embry-Riddle Aeronautical University as an administrative director
Founding President of
a chapter of Women in Aviation, International
Member of NAFI
(National Association of Flight Instructors)
Experience
Sarina Houston is a
former writer for The Balance Careers covering aviation and aerospace. Houston
is an FAA-certified Commercial Pilot and Flight Instructor with Single and
Multi-Engine Instrument ratings. She has been a flight instructor since 2005.
In addition to flying,
Houston has experience in administrative and nonprofit management. She has
worked for Embry-Riddle Aeronautical University as an administrative director,
and was the founding President of a chapter of Women in Aviation,
International—a nonprofit organization that provides support for women and men
who choose to enter the challenging world of aviation.
She maintains
professional memberships with AOPA (Aircraft Owners and Pilots Association),
WAI (Women in Aviation, International), and NAFI (National Association of
Flight Instructors).
Houston currently
works as an independent flight instructor and a freelance aviation writer.
Education
B.S. in Aeronautical
Science, Embry-Riddle Aeronautical University
M.S. in Aeronautical
Science, ERAU-Worldwide, specializing in Aviation Safety and Operations
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