When is refueling not permitted in an air taxi with passengers on board?

Fueling an air taxi with passengers on board is a critical safety consideration. The correct answer emphasizes that refueling should not occur without the presence of the pilot-in-command (PIC) to monitor the fueling process. This requirement is in place to ensure that all safety protocols are followed, as the PIC is responsible for the safety of the passengers and the aircraft.

When the PIC supervises the fueling, they can ensure that proper procedures are being followed, and any potential hazards can be addressed immediately. This supervision minimizes the risk of accidents, such as fuel spills or improper fueling practices, which can pose significant risks to passengers and the overall flight safety.

The options regarding weather conditions, fuel capacity, and nighttime operations may reflect other safety concerns but do not specifically address the importance of direct oversight by the PIC during refueling operations. Therefore, the correct answer highlights the necessity of having the PIC present, underscoring the importance of oversight and safety in passenger operations.