Featureless Terrain Illusion Atmospheric Illusions Ground Lighting Illusions Helicopter Night VFR Operations Chapter Summary 12-10 1.  The sky cover is less than broken (less than  5 ⁄ 8 cloud  cover), the time is between the local moon rise and  moon set, and the lunar disk is at least 50 percent  illuminated; or 2.  The aircraft is operated over surface lighting that, at  least, provides lighting of prominent obstacles, the  identification of terrain features (shorelines, valleys,  hills, mountains, slopes) and a horizontal reference  by which the pilot may control the helicopter. For  example, this surface lighting may be the result of: a.  Extensive cultural lighting (manmade, such as a  built-up area of a city), b.  Significant reflected cultural lighting (such as the  illumination caused by the reflection of a major  metropolitan area’s lighting reflecting off a cloud  ceiling), or c.  Limited cultural lighting combined with a  high level of natural reflectivity of celestial  illumination, such as that provided by a surface  covered by snow or a desert surface. An absence of ground features, as when landing over water,  darkened areas, and terrain made featureless by snow, can  create the illusion that the aircraft is at a higher altitude than  it actually is. The pilot who does not recognize this illusion  will fly a lower approach.  Rain on the windscreen can create the illusion of greater  height, and atmospheric haze can create the illusion of being  at a greater distance from the runway. The pilot who does not  recognize these illusions flies a higher approach. Penetration  of fog can create the illusion of pitching up. The pilot who  does not recognize this illusion steepens the approach, often  quite abruptly.  Low lighting conditions are those that do not meet the high  lighting conditions requirements. Lights along a straight path can be mistaken for runway  and approach lights. This might include street lights along a  roadside or even the internal lights of a moving train. Another  illusion may occur with very intense runway and approach  lighting. Due to the relative brightness of these lights, the  pilot may perceive them to be closer than they really are.  Assuming that the lights are as close as they appear, the  pilot may attempt an approach that is actually lower than  glideslope. Conversely, the pilot flying over terrain with few  lights may make a lower than normal approach. Some areas may be considered a high lighting environment  only in specific circumstances. For example, some surfaces,  such as a forest with limited cultural lighting, normally  have little reflectivity, requiring dependence on significant  moonlight to achieve a high lighting condition. However,  when that same forest is covered with snow, its reflectivity  may support a high lighting condition based only on starlight.  Similarly, a desolate area, with little cultural lighting, such as  a desert, may have such inherent natural reflectivity that it  may be considered a high lighting conditions area regardless  of season, provided the cloud cover does not prevent starlight  from being reflected from the surface. Other surfaces, such  as areas of open water, may never have enough reflectivity or  cultural lighting to ever be characterized as a high lighting area. While ceiling and visibility significantly affect safety in night  VFR operations, lighting conditions also have a profound  effect on safety. Even in conditions in which visibility and  ceiling are determined to be visual meteorological conditions,  the ability to discern unlit or low contrast objects and terrain  at night may be compromised. The ability to discern these  objects and terrain is referred to as the “seeing condition,”  and is related to the amount of natural and man-made  lighting available, and the contrast, reflectivity, and texture  of surface terrain and obstruction features. In order to conduct  operations safely, seeing conditions must be accounted for in  the planning and execution of night VFR operations. Through the accumulation of night flying experience in a  particular area, the pilot develops the ability to determine,  prior to departure, which areas can be considered supporting  high or low lighting conditions. Without that pilot experience,  low lighting considerations should be applied by pilots for  both preflight planning and operations until high lighting  conditions are observed or determined to be regularly  available. Even if the aircraft is certified for day and night  VFR conditions, night flight should only be conducted if  adequate celestial illumination is assured during the entirety  of the flight. Night VFR seeing conditions can be described by identifying  high lighting conditions and low lighting conditions. High lighting conditions exist when one of two sets of  conditions are present: Knowledge of the basic anatomy and physiology of the eye  is helpful in the study of helicopter night operations. Adding 