perpendicular to the runway centerline lights. They generally extend from the landing
threshold to 3,000 feet down the runway at 100-foot intervals.
Taxiway edge lights are blue. Their spacing is variable and depends upon the length of
a straight segment of a taxiway or the radius of curvature on a taxiway turn. On straight
segments over 300 feet in length with lighting along both edges, lights are placed up to
200 feet apart. On straight segments over 300 feet in length with lights along one edge,
lights are placed up to 100 feet apart. On straight segments of 300 feet or less with
lights along one or both edges, lights are placed up to 50 feet apart. Taxiway lights that
mark a curved edge of a taxiway follow the rule that the sharper the radius of curvature
the closer the lights are placed.
At some naval air stations, taxiway centerline lights are used to supplement edge lights
wherever more positive guidance of aircraft is necessary, such as at complex taxiway
intersections or large ramp areas where pilot confusion might occur. They are also used
to add directional guidance at high speed taxiway exits. Taxiway centerline lights are
Approach lighting systems of varying types, colors, and construction have been
specifically developed to meet civil and military requirements. These lights are installed
in areas extending outward from the threshold of the instrument runway and are usually
pilots first visual contact with the ground under extremely low-visibility conditions.
Electronic landing aids such as ground control approach (GCA) and instrument landing
system (ILS) are used to bring the pilot down to approach minimums. Approach lights
are required for the pilot's final alignment with the runway, and runway lights are
required for completion of the landing.
The approach lighting system normally consists of a series of crossbars of white lights
in the approach zone immediately ahead of the runway threshold with the standard
length being 3,000 feet. The system also includes high-intensity blue-white sequence
flashing lights (strobes) placed on the extended centerline from 1,000 feet to 3,000 feet
from the runway threshold.
The intensity of the approach lights can be varied from the control tower. To be most
useful, the lights must be sufficiently bright to penetrate the overcast effectively without
blinding the pilot or producing halo effects. The sequenced flashing lights are controlled
independently of other lights and are either on or off. They are, however, a component
of the approach lights; therefore, the approach lights must be on before the sequenced
flashing lights will operate. You should be alert during periods of low visibility and fog
because the pilot will often request "strobes off" on short final. When rebounding off the
fog, strobe lights can produce a blinding effect for the pilot.
Information about the various configurations of approach lighting systems available
today is contained in both the Flight Information Handbook and the Aeronautical