What factors commonly lead to instrument approaches?

Instrument approaches are primarily influenced by external conditions, which typically include weather conditions, terrain obstacles, and air traffic control requirements. Weather conditions, such as low visibility, storms, or inclement weather, can limit a pilot's ability to conduct visual approaches, necessitating the use of instrument approaches to ensure safety.

Terrain obstacles, like mountains or tall buildings, can also obstruct pilot visibility, requiring an instrument approach to navigate safely and comply with regulations that prioritize aircraft separation and obstacle avoidance. Furthermore, air traffic control requirements may dictate the type of approach to ensure orderly and safe traffic flow, especially in busy airspace.

While factors such as aircraft weight and balance, flight crew experience, and fuel load are important for overall flight safety and performance, they do not directly influence the decision to conduct instrument approaches in the same way that weather, obstacles, and ATC requirements do. These factors are more about aircraft performance and operational capabilities.