What action should be taken if fuel vapour is detected inside the aircraft?

When fuel vapour is detected inside the aircraft, the most critical and immediate action is to evacuate passengers. Fuel vapour presents a significant safety hazard due to its flammable nature, which could lead to a fire or explosion in an enclosed space like an aircraft. The safety of passengers and crew is the highest priority, and protecting them from potential harm must be addressed promptly.

Evacuating passengers helps to ensure their safety by moving them away from the source of danger as quickly as possible. Immediate evacuation allows the cabin crew to manage the situation effectively and coordinate with emergency services if required. It also prevents possible panic among passengers, as they will be guided through a clear and safe evacuation process.

The other options, such as informing the cabin crew only, continuing with boarding, or checking for leaks visually, do not sufficiently address the urgent nature of the fire risk posed by fuel vapour. While communication and assessment are important aspects of emergency procedures, they should occur after ensuring that all individuals onboard are safe from immediate danger.