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reference to the horizon, the pilot must be prepared to fly IFR. 

• Will the flight conditions allow a safe emergency landing at night? 

• Preflight all aircraft lights, interior and exterior, for a night flight. Carry at least two flashlights—one for exterior preflight and a smaller one that can be dimmed and kept nearby. [Figure 3-8] 

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The human eye will see nothing outside that is dimmer than the flight deck lighting. Always fly at night with the interior lights as dim as possible. As the flight progesses and the eyes adjust to the darkness, usually the interior lights can be dimmed further, aiding the outside vision. If the interior lights will not dim, that would increase the risk factors by restricting the pilot’s outside vision—probably not the time for a night flight. 

## Visual Illusions 

Although weather, terrain, airport conditions, and night versus daylight flying each produce unique challenges, together these factors conspire against a pilot’s senses. It is important to understand that unwittingly these factors can create visual illusions and cause spatial disorientation producing challenges the pilot did not anticipate. [Figure 3-9] Even the best trained pilots sometimes fail to recognize problem until it is too late to complete a flight safely. 

An accident involving a Piper PA-32 and an airline transport pilot illustrates how visual illusions can create problems that lead to an accident. In this case, the aircraft collided with terrain during a landing. The sole occupant of the airplane was an airline transport pilot who was not injured. The airplane owned and operated by the pilot, sus tained substantial damage. The personal transportation flight was being operated in visual meteorological conditions (VMC) in mid-afternoon. Although it was not snowing, there was snow on the ground. 

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