Originally Posted by Aterpster
At an airport such as BHM I presume the FAA had verified these PAPIs as being correctly aligned. Otherwise, the two approaches would have categorically been NA at night because the visual segment is encumbered by penetrations of a 34:1 slope in the visual segment and, perhaps even a 20:1 slope (higher terrain a bit left of centerline with lots of trees and homes.
The approach charts for both R18 approaches contain the note that the procedure is NA at night, which seems to support your presumption.