JO 7110.65 3-4-3

VASI systems with remote on-off switching must be operated when they serve the runway in use and where intensities are controlled in accordance with TBL 3-4-2 and TBL 3-4-3 except:

As required by facility directives to meet local conditions.

As required by the pilot. TBL 3-4-2 VASI Intensity Setting-Two Step System Step

Period/Condition

High

Day-Sunrise to sunset.

Low

Night-Sunset to sunrise.

TBL 3-4-3 VASI Intensity Setting-Three Step System Step

Period/Condition

High

Day-Sunrise to sunset.

Medium

Twilight-From sunset to 30 minutes after sunset and from 30 minutes before sunrise to sunrise,* and during twilight in Alaska.

Low

Night-Sunset to sunrise.

*During a 1 year period, twilight may vary 26 to 43 minutes between 25 and 49N latitude.

NOTE-

The basic FAA standard for VASI systems permits independent operation by means of photoelectric device. This system has no on-off control feature and is intended for continuous operation. Other VASI systems in use include those that are operated remotely from the control tower. These systems may consist of either a photoelectric intensity control with only an on-off switch, a two step intensity system, or a three step intensity system.

REFERENCE-

FAA Order JO 7210.3, Para 10-6-5, Visual Approach Slope Indicator (VASI) Systems.

FAA Order 6850.2, Visual Guidance Lighting Systems.