Operations where an operational ATC unit is providing service with only one appropriately qualified ATCO on duty.
Source: IFATCA
Description
There are two types of Single Person Operations (SPO) in ATM:
position staffed by a single person (sector operated by one person)
an Ops room staffed by a single person
SPO is typically used during nighttime or low-workload periods. It is not suitable for high workload or degraded systems conditions. Contingency plans need to be in place in case either of these occurs.
The benefits of SPO are optimal use of available personnel and cost reduction. It is sometimes used as a measure against fatigue caused by too many shifts due to controller shortage. Neglecting the issue (i.e. failing to compensate the shortage within a reasonable period of time) however, can have the opposite effect.
Due to a number of safety concerns, SPO should only be implemented after a thorough examination which determines the conditions under which it is acceptable as well as the measures to eliminate or sufficiently mitigate the associated hazards.