When must the main doors be monitored or manned?

The main doors of an aircraft must be monitored or manned whenever passengers are on board and the aircraft is on the ground to ensure safety and security. This requirement serves several critical purposes: ensuring that the doors are secure and cannot be inadvertently opened during operations that could lead to safety hazards, such as fueling or servicing the aircraft, and helping to manage the passenger boarding and deplaning processes effectively.

Having personnel available at the doors also allows for quick response in case of emergencies or unexpected situations, ensuring that passengers can be safely evacuated if necessary. Furthermore, this practice aligns with aviation safety regulations and protocols, which establish clear procedures for managing passenger safety from the moment they step onto the aircraft to when they disembark.

Monitoring or manning the doors is not necessary during cruising altitude since the aircraft is in a stable flight condition, and there are typically no passenger ingress or egress during this phase. Similarly, bad weather and takeoff or landing phases require other safety measures and considerations but do not specifically mandate continuous monitoring of the main doors in the same way as when passengers are on board and the aircraft is on the ground.