If you’re in the Executing Phase it is the Project Manager’s responsibility to make sure that the team is performing their tasks on schedule and to deal with a team member’s vacation, or absence. As @cdj24 mentions, it should be communicated in the planning phase if a team member is planning to take a big vacation or be absent from work. However, I believe that if the team member decides after the Planning phase to take a vacation, that he/she would require approval from the project manager. In my office we have “Time Away forms” where we select what we are requesting time taken “Vacation, Scheduled Sick day (doctor appointment), Bereavement, etc” and then our manager has to sign off and the office admin puts the information in the “Time Away Calendar” that everyone in the office has access to. This I think would be the best process because in this situation the Project Manager can see if it would be appropriate with the Project timeline if that team member can take off or if they are required to meet certain deliverables. There will definitely be situations where the will be a family emergency or personal problem and the Project Manager will have to see as @cdj24 mentions if they can work remotely, be replaced, or have someone cover their responsibilities while they are out. Overall, I don’t think there should be too many surprises with team members taking vacation or taking time off, but there should be a company process so that there is a clear dialog with the team members and manager so the project can meet its milestones and timeline for deliverables is adhered to. Everyone knows people will take vacation, get sick, have a family emergency so this should be accounted for in the planning stage and a process implemented for when these occur.