When is it not allowed to refuel an air taxi flight with passengers on board?

Refueling an air taxi flight with passengers on board is generally prohibited when the pilot-in-command is not available because the pilot's presence is crucial for safety and oversight during the refueling process. The pilot-in-command is responsible for ensuring that all safety protocols are followed, and their presence is necessary to manage any potential emergencies or unforeseen situations that may arise during refueling. This includes monitoring the operation, ensuring that only qualified personnel are conducting the fueling, and maintaining communication with ground control and onboard passengers.

Fueling practices are governed by strict safety regulations meant to protect both passengers and crew. This is especially important in an air taxi operation, where the safety of multiple passengers is at stake. If the pilot is unavailable, there is no one present to maintain this level of oversight, increasing the risk involved with refueling.

Other options do present scenarios that could complicate the refueling process, such as poor weather or operating after hours, but these situations do not inherently prevent refueling with passengers on board. Similarly, if the aircraft is parked, it could still be safely refueled as long as the pilot-in-command is present to oversee the process.