Which documents must pilots check as part of required preflight action?

The requirement for preflight action emphasizes the importance of understanding the operating environment for a safe flight. Among the considered choices, checking ATC traffic delays and runway lengths is essential for a pilot to effectively plan their departure and arrival procedures. This information helps the pilot anticipate and manage potential delays en route, allowing them to adjust their flight plan accordingly. Knowing the runway lengths is crucial to ensure that the aircraft can safely take off and land, considering factors such as aircraft weight, weather conditions, and runway surface.

In contrast, while aircraft registration and weight and balance are important for regulatory compliance and ensuring the aircraft is loaded within its operational limits, they do not directly address traffic conditions or landing infrastructure. Flight logs and aircraft maintenance records are relevant for the aircraft's airworthiness but don't provide immediate situational awareness regarding traffic or runway specifications at time of flight. Lastly, weather forecasts and sectional charts are critical for navigation and safety, but they do not cover the traffic delays that can directly impact a pilot's flight plan and operational decisions.