What is a common risk for pilots when flying at night?

Reduced visibility leading to misperception of distances is a significant risk for pilots flying at night. At night, the lack of natural light can obscure visual cues that are otherwise readily available during the day. This diminished visibility affects depth perception and can lead to difficulty judging distances to objects, such as the runway or other aircraft. Additionally, the absence of familiar ground references that are easily noted during daytime flying can cause pilots to misjudge their altitude and distance to objects below them.

While the other choices may present challenges, they are not as universally applicable to night flying as the issue of reduced visibility. For instance, over-reliance on ground references tends to be less of a concern at night, since visibility is limited, and pilots are more likely to rely on instruments. Similarly, many pilots are trained to use their navigation equipment proficiently, regardless of the time of day. While air traffic may increase in certain areas at night, it is not a direct consequence of flying at night compared to the more immediate issue of misperception due to reduced visibility. Therefore, the intrinsic challenges of reduced visibility and distance misperception make this a common and notable risk for nighttime flying.