Crew assignments call for being on duty one day and off duty the next until 72 hours are worked on duty. At that time, the crew is relieved of duty for four days.
The work schedule covers a 28-day period with three alternating crews (A, B, and C), each of which work 24 hours starting at 7:00 am and ending at 7:00 am the next day. Holidays and weekends are not considered when determining duty schedules.