Shift plan

The shift plan or rota is the central component of a shift schedule in shift work. The schedule includes considerations of shift overlap, shift change times and alignment with the clock, vacation, training, shift differentials, holidays, etc. The shift plan determines the sequence of work (W) and free (F) days within a shift system.

A notation used often identifies day (D), swing (S) and night (N) shifts for the W days and O (off) for rest days.

Note that a worker transitioning from N to O works for the first six or seven hours of the first day "off". Thus, when days off follow night shifts, the first one or more days "off" are, in fact, days of recovery from lack of nighttime sleep. Note also that this daily notation refers to the start of a shift. If a shift starts at 23:00, then this is a W day even though only one hour is worked. The day after this shift is an F day if no shift starts on this day, though many hours have been worked from midnight on.

One shift system may allow many shift plans. For example, the twelve-hour, 2nW:2nF system with n = 1 allows twelve different plans in three serially-identical sets. Within a set, DONO has the same sequence as NODO. DNOO is the preferred sequence because days off follow night work and there are two consecutive days off.

The US Navy uses a three shift system with an 18-hour day instead of a 24-hour day. The 24-hour period is divided into four shifts: 00:00-06:00, 06:00-12:00, 12:00-18:00, and 18:00-00:00. A sailor stands watch on their shift. During the off shift there is time to perform maintenance, study for qualifications and handle collateral duties. During off time the sailor has time to sleep, relax, and perform personal tasks, such as laundry.

This does not apply to the attached air wing, which will work a 12 on, 12 off schedule 7 days a week.

Submarine sailors in the US Navy use a plan known as sixes while underway. The ship operates on an 18-hour schedule. An individual is scheduled to stand watch for 6 hours, perform any other duties and engage in leisure time for 6 hours, then sleep for 6 hours. With sufficient personnel, a given watchstation may benefit from a fourth man (the midnight cowboy). He will stand the same 6-hour watch in a given 24-hour period, usually from midnight to 06:00 (hence themidnight portion of the name, often shortened to cowboy) and the normal watchstander is free. This gives rise to a schedule of six on, twelve off, six on, thirty off, six on, twelve off.

In the 12/24/12/48 or 12/24 plan, employees work in shifts of 12 hours; first a "daily shift" (e.g. 06:00 to 18:00), followed by 24 hours rest, then a "nightly shift" (18:00 to 06:00), finishing with 48 hours rest. This plan needs four teams for full coverage, and makes an average 42-hour workweek. The pattern repeats in a 4-week cycle, i.e. over 28 days, and has 14 shifts per employee therein.

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