Airport
Lighting Aids
1.
Runway approach ramps
Simple version of approach lights
A simple form of approach lighting consists of
a low intensity white centerline and cross bar. It starts 500 meters earlier to
the runway edge (the green lights).
Figure
1: Simple Approach Light System
Precision version of approach
lights
Airfields can have more difficult approach lighting systems used
mainly in link with ILS equipped runways. A well-known system is the Calvert
Approach lighting system. The Calvert system consists of a white centerline and
5 white cross bars. It starts 900 meters earlier to the runway edge. At airfields
where CAT II and III approaches are conducted, supplementary approach lights
are added to the system. Supplementary approach lights are installed the last
300 meters earlier the runway edge, consist of a white Centerline barrette and
two red side barrettes.
| Figure 2: Calvert Approach light system |
2. Visual Approach Slope Control
Precision
Approach Path Indicator (PAPI)
The PAPI provides a visual aid to determine the correct approach
path. It contains single row of 4 red
and white lights. The color is depending on the vertical angle as shown in the
diagram hereunder.
Figure 3a: PAPI light system
Figure 3b: PAPI light arrangement
PAPI’s are not designed to be used outside 15° of the runway
centerline. PAPI’s are usually located to the left side of the runway. But,
where this is impossible, it can be mounted on the right side of the runway.
There also are airfields where PAPI’s are placed on both sides of the runway.
Where a PAPI is used together with an ILS, it is located to align both glide
slopes as much as possible.
Visual
Approach Slope Indicator (VASI)
A VASI system does greatly the same as a PAPI system. It is just a
different arrangement.
It contains two rows of two red and white lights which the arrangement
is as shown below:
Figure
4: VASI light arrangement
VASI systems may consist of 2, 4, 6,
12, or 16 light units arranged in bars referred to as near, middle, and far
bars. Most VASI systems consist of 2 bars, near and far, and may consist of 2,
4, or 12 light units. Some VASIs consist of three bars, near, middle, and far,
which provide an additional visual glide path to accommodate high cockpit
aircraft. This installation may consist of either 6 or 16 light units. VASI
installations consisting of 2, 4, or 6 light units are located on one side of
the runway, usually the left. Where the installation consists of 12 or 16 light
units, the units are located on both sides of the runway.
T - VASI
A variation
of the VASI is the T-VASI, which presentation is as shown below:
Figure
5:T-light arrangement
Runway lighting
All
runways certified for night operations shall have:
· Runway Edge Lights
·
Runway Threshold and Runway End
Lights
Note that centerline
and touchdown zone lights are additional guidance in support of low visibility
operations.
Runway edge lights
Edge
Lights are white lights situated along the edges of the stated runway width
spaced at 60 meters.
Figure 6a:
Runway edge lights
Figure 6b: Runway edge lights
They
are white except for:
·
Caution Zone Lights
·
Pre-Threshold Lights
·
Runway Exit Lights
·
Stop way Lights
Caution Zone Lights
Yellow
caution zone lights are installed on ILS equipped runways without centerline
lights, on the last 600 meter.
Pre- Threshold Lights
On a runway
with a displaced landing threshold (an available area in front of the threshold
for the take-off run and not the landing), the runway edge lights from the
beginning of the pavement up to the displaced threshold are red. Where the area
in front of the threshold is narrower than the associated runway width, the
edges are lighted is blue.
Runway Exit Lights
One or two
Omni-directional blue lights may replace or supplement the edge lights to
indicate an exit taxiway.
Stop way Lights
Where a stop
way is provided the edge lights are red and facing one way so only the landing
traffic is able to see them. A stop way is for emergency use only, and not for
routine landings.
Runway threshold and runway end
lights
Runway
Threshold lights are always seen green by a pilot on final, indicating the
start of the available landing distance. Runway End lights are always seen red,
indicating the boundary of the runway available for guiding.
Runway centerline lights
For runways
supporting low visibility operations high intensity runway centerline lights
are installed.
Runway
centerline lights are color coded:
·
From the threshold until 900
meters from the runway end the centerline lights are white.
·
The next 600 meters are
alternating red and white lights.
·
The last 300 meters are only red
lights.
Runway
centerline lights are spaced each 30 meters. However for CAT III runway
operations, they are spaced each 15 meters.
Figure 8: Runway
centerline lights
Touchdown zone (TDZ) lights
For runways
supporting low visibility operations additional touchdown zone lights,
consisting of two rows of white barrettes are installed. The touchdown zone
lights extend from the threshold light bar for 900 meters or the midpoint of
the runway, whichever is the shorter distance.
Figure 9: Touchdown zone lights
Rapid Exit Taxiway Indicator Lights (RETIL)
Rapid exit taxiway indicator lights consist of six yellow lights in a three/two/one configuration, spaced 100 meters apart (Where the single yellow light is situated 100 meters from the start of the turn).
Figure 10:Rapid Exit Taxiway indicator lights
3. Taxiway Lighting
Taxiway
edges are provided with blue edge lighting. Green taxiway centerline lights are
provided for low visibility procedures (Where green centerline lights are provided,
blue edge lights may also be provided).
Figure 11: Taxiway Lighting
Stop bar
Airfields approved
for low visibility operations have stop bars lights. Stop bars lights consist
of equally spaced red lights across the taxiway at a 90° angle to the taxiway centerline.
Stop bars are situated at runway entry’s and holding points. They may also be
installed at taxiway intersections (e.g. connected with a taxiway guidance
system). Normally stop bars are installed
connected with green lead-on lights.
Figure 12:stop bar
Runway guard lights
Runway guard
lights are two
pairs of alternately
flashing yellow lights.
Each pair located next to the taxiway indicating close proximity to the
runway. Where a taxiway is wider than usual an alternate variation may be
installed, where additional pairs of alternately flashing yellow lights are
installed into the taxiway across the full width.
Figure 13:Runway guard light
