What is the primary function of the No.3 PDI?

The primary function of the No.3 PDI is to conduct checks at the R2 door. This role is critical for ensuring that the door is secure and that all safety protocols related to the boarding and deboarding processes are adhered to. The No.3 PDI, frequently in charge of overseeing various operational aspects during the flight preparation and servicing phases, plays a vital role in maintaining the integrity of the aircraft's safety systems and passenger flow.

While other choices may pertain to important operational tasks, they do not align with the specific responsibilities designated to the No.3 PDI. For instance, conducting toilet checks, checking cabin rows 1-10, and checking the function of the inflight entertainment system are tasks assigned to other crew members or different roles within the cabin crew structure. The focus on conducting checks at the R2 door highlights the importance of safety and efficiency in aircraft operations, particularly in relation to passenger accessibility and emergency preparedness.