Final answer:
On Open Assignment trips, sign-up for positions is required at the beginning of each duty period or with a change of aircraft type or crew complement. Therefore correct answer is option 2.
Step-by-step explanation:
The question asks about the process by which crew members sign up for positions at the beginning of their duty period or when there is a change of aircraft type or crew complement. The correct option to fill in the blank is Option 2: Open Assignment.
In airline operations, an open assignment system provides flexibility, as it allows crew members to sign up for positions on trips that have not been previously assigned to them. This contrasts with a pre-assigned system where crew members are given their schedules in advance, a rostered system that follows a set rotation, or a dynamic system that may change according to various operational needs.
For open assignment trips, sign-up is necessary at the start of the duty period to ensure that crew members are aware of their responsibilities and any potential changes in the aircraft they will be operating or the crew members they will be working with.