These individual duties are rotated among the staff about every two hours at busy locations. At busy times, controllers must work rapidly, and mental demands increase as traffic mounts, especially when poor flying conditions occur and traffic stacks up. Brief rest periods provide some relief, but are not always possible. Radar controllers usually work in semi-darkness. Some jobs are located outside the contiguous United States in Alaska, Hawaii, Puerto Rico, the Virgin Islands, and American Samoa.
Employees are able to relocate to meet staffing requirements.
The starting grade is normally GS-7. Trainees are paid while learning their jobs. Promotion from trainee to a higher-grade professional controller depends upon the employee's performance and satisfactory progression in his or her training program. Trainees who do not successfully complete their training courses are separated or reassigned from their controller positions. During the first year, the trainee is on probation and then she or he may advance from positions backing up professional controllers to primary positions of responsibility.