What is the effective visual range of the PAPI at night?

• A. 10 miles
• B. 15 miles
• C. 20 miles
• D. 25 miles

Answer: (C)

The visual glidepath indicator is there to give you a readable cue of your descent angle on final. The lights are designed to be bright enough to be detected and interpreted from about 20 miles away under typical night conditions, so you have a solid lead to establish and correct your approach before you’re very close to the runway. Night conditions can dull depth perception and color discrimination, but the PAPI’s brightness and spacing make its cue reliable out to roughly twenty miles; beyond that, visibility of the lights becomes uncertain and you shouldn’t rely on it for guidance. So, the effective visual range at night is about 20 miles.