30 40 50 60 70 80 90 30.0 29.9 29.8 Figure 12-11.  A properly lit instrument panel and city lights provide  recommended conditions for night flying. Figure 12-10.  Digital panel instrument gauges for WSC aircraft. Figure 12-9. Classic instrument gauges for WSC aircraft. pilot fl ying under VFR must exercise caution to  avoid flying into clouds or a layer of fog. Usually,  the first indication of flying into restricted  visibility conditions is the gradual disappearance  of lights on the ground. If the lights begin to take  on an appearance of being surrounded by a halo  or glow, the pilot should use caution in attempting  further flight in that same direction. Such a halo  or glow around lights on the ground is indicative  of ground fog. Remember that if a descent to land  must be made through fog, smoke, or haze, the  horizontal visibility is considerably less. Under  no circumstances should a night flight be made  during poor or marginal weather conditions. The pilot should practice and acquire competency  in straight-and-level flight, climbs and descents,  level turns, climbing and descending turns, and  steep turns. The pilot should also practice these  maneuvers with all the flight deck lights turned  off. This blackout training is necessary if the  pilot experiences an electrical or instrument light  failure. Training should also include using the  navigation equipment and local NAVAIDs. In spite of fewer references or checkpoints, night  cross-country flights do not present particular  problems if preplanning is adequate, and the pilot  continues to monitor position, time estimates, and  fuel consumption. The GPS is the most valuable  instrument for day and night cross-country fl ying.  For night cross-country flying, spare batteries or  a GPS hooked to the aircraft electric system with  a battery backup is recommended. NAVAIDs,  the aircraft has climbed to an altitude at which the light  beam no longer extends to the surface. The light can cause  distortion when it is reflected by haze, smoke, or fog that  might exist in the climb. Therefore, when the landing light  is used for the takeoff, it may be turned off after the climb is  well established provided other traffic in the area does not  require its use for collision avoidance. A properly lit instrument panel and visual reference to the  ground with city lights are recommended for night fl ying.  [Figure 12-11]  At night, it is usually difficult to see clouds and restrictions to  visibility, particularly on dark nights or under overcast. The   Orientation and Navigation 12-10