Which of the following situations requires reevaluation of the sling load?

Reevaluation of the sling load is crucial whenever there is a shift in the load during transport. A shifting load can alter the center of gravity, affect the load's balance, and potentially compromise the safety and stability of the aircraft. It can lead to dangerous flight conditions, making it essential for the flight crew to reassess the situation to ensure that the load can be carried safely. If the load is not properly secured or if it shifts unexpectedly, it can result in a catastrophic failure during flight.

The other situations do not inherently require a reevaluation of the sling load. For instance, improvements in weather conditions may enhance the safety and feasibility of the flight, but they do not directly affect the status of the load itself. Changes in flight crew could lead to a reassessment of protocols and procedures but are not necessarily linked to the stability of the current load. Similarly, increased light levels do not impact the physical positioning or safety of the load being transported. Therefore, monitoring for load shifts is the primary factor necessitating reevaluation to maintain operational safety.