What must be ensured on the flight deck when refueling occurs with passengers onboard?

When refueling occurs with passengers onboard, it is crucial that the flight deck is manned by at least one pilot. This ensures that there is always someone in command who can respond to any emergency situation that may arise during the refueling process. Keeping a pilot on the flight deck allows for immediate decision-making and handling of potential safety concerns, which is particularly important when passengers are present, as their safety is paramount.

Having a pilot in the flight deck during refueling helps maintain oversight of the situation, ensuring effective communication with ground crews and an ability to take quick action if needed. This is a critical safety protocol that aligns with regulatory standards concerning the presence of personnel capable of managing the aircraft and the safety of those onboard.