PAPI systems with remote on-off switching shall be operated when they serve the runway in use and where intensities are controlled in accordance with TBL 3-4-4 except:
NOTE: The basic FAA standard for PAPI systems permits independent operation by means of photoelectric device. This system has no on-off control feature and is intended for continuous operation. Other PAPI 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, or a five-step intensity system.
|5||On Pilot Request|
|4||Day - Sunrise to sunset|
|3||Night - Sunset to sunrise|
|2||On Pilot Request|
|1||On Pilot Request|
|*During a 1 year period, twilight may vary 26 to 43 minutes between 25 and 49N latitude.|