What is an example of a visual illusion experienced by pilots?

A false horizon is a notable visual illusion that pilots may encounter, particularly when flying in conditions where the true horizon is obscured or indistinct. This can occur in situations such as flying over flat terrain, water, or in clouds and fog, where environmental cues are limited. The absence of a clear horizon can lead pilots to mistakenly align their aircraft with misleading visual references, such as lights on the ground or other terrain features that do not accurately depict the natural horizon.

Understanding this phenomenon is crucial for pilots, as it can result in miscalculations during flight, especially during critical phases like takeoff and landing. Recognizing the potential for visual illusions helps pilots to rely more on their instruments, promoting safer flight operations.

In contrast, the other choices do not represent visual illusions. Cloud formations may affect visibility but do not create the misleading references associated with illusions. Wingtip vortices refer to air disturbances created by an aircraft and are not visual cues. Lastly, sunny weather, while it can offer good visibility, does not inherently cause visual illusions.