Refuelling with passengers embarking, on board or disembarking
Occasionally, it might be necessary to refuel when passengers are still disembarking or a new bunch of passengers is boarding or even when transit passengers remain on board during a refuelling stop. In these circumstances, additional safety precautions are applied:

• The full number of cabin crew must be on board (the number corresponding to the minimum number of flight attendants for a flight).
• They must occupy their stations near the emergency exits (no catering handling, assisting passengers with baggage stowage, etc.).
• Passengers must be informed about fuelling in progress (by an on-board public address system and/or at the gate before boarding).
• The "Fasten your seat belts" sign must be switched off and passengers asked not to fasten their belts for quick evacuation.
• At least two escape paths depending on the size of the aircraft must be available (doors open with the bridge/airstairs connected or doors closed with an armed slide and the area below free from vehicles and objects for slide activation).
• Two-way communication maintained between personnel supervising refuelling and the cockpit for quick evacuation initiation.
• At most airports, fireman supervision or at least notification and monitoring through CCTV cameras is required.
• Such refuelling can only be done with low-risk fuels such as Jet A1. Wide-cute fuels and AVGAS are unsuitable due to their higher risk of ignition and hence can only be refuelled/de-fuelled if passengers are not on board, boarding nor disembarking.

Source: EASA AIR OPS - AMC1 NCC.OP.155 Refuelling with passengers embarking, on board or disembarking