but whose beams are directed away from the tower, may become objectionable due to light being back-reflected off water droplets and/or snowflakes. It is recognized that this problem cannot be eliminated entirely because the nature of the airport environment predisposes that at least some luminaires will be in the line of sight of the tower Operator. Within the limits of practicality, however, the luminaires should not be placed so as to become visual obstructions in certain critical directions, such as that towards the approaches, runways, and taxiways.