What factors influence the decision to initiate a go-around?

Initiating a go-around is a critical maneuver that pilots must execute under certain circumstances to ensure the safety of the flight. The correct choice highlights several key factors that directly pertain to the integrity of the approach and landing phase.

Poor visibility can significantly impact a pilot's ability to assess the landing environment effectively, leading to a go-around decision if the runway and its surroundings cannot be clearly seen. An unstable approach is another crucial reason for initiating a go-around, as it indicates that the aircraft is not on the proper flight path or configuration for a safe landing. This could involve being too high, too fast, or misaligned with the runway centerline. Lastly, unexpected obstacles on the runway, such as other aircraft, vehicles, or debris, present immediate hazards that necessitate a go-around to avoid potential collisions or accidents.

While pilot fatigue and experience level, flight plan discrepancies, and weather conditions certainly play roles in flight safety and decision-making, they are not as directly connected to the specific scenario of executing a go-around during the landing phase. The primary focus during this phase is the immediate operational environment related to the approach and runway. Thus, the factors cited in the correct answer encapsulate the most critical reasons to initiate a go-around effectively.