UFC 3-535-01
17 November 2005
Power the threshold lights with the associated runway edge lights. Connect to the HIRL
series circuit. Emergency and automatic transfer requirements are the same as for
HIRL.
4-4.7
Control Requirements
4-4.7.1
Where there is no approach light system, provide remote on and off and
three intensity levels through the runway edge light controls.
4-4.7.2
When installing approach lights, the threshold lights may be circuited so
approximately half of them are controlled by the approach light system. Interleave the
threshold lights selected for operation with the approach lights, with the threshold lights
to be operated with the runway lights so they present a uniform pattern symmetrical
about the runway centerline when operated without runway lights. This may require that
the two innermost lights be operated off the same circuit. Wherever possible, the lights
selected for operation with the approach lights should not be bi-directional fixtures with
runway end lights installed.
4-4.8
Aiming Threshold/ Approach
When used as part of an approach light system, bi-directional threshold lights, both in-
pavement and elevated, have fixed aiming angles (with 3.5 to 4.0 degree toe-in on the
red side only) for the beams and therefore cannot be adjusted.
4-4.9
Monitoring Requirements
Threshold lights have the same monitoring requirements as the edge lights.
4-4.10
Compliance with International Military Standards
4-4.10.1
NATO
The standard meets NATO STANAG 3316 for high intensity threshold lights.
4-4.10.2
ASCC
The standard meets ASCC AIR STD 90/27, for high intensity threshold lights.
4-4.11
Additional Information
See FAA AC 150/5345-46 for more information.
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