Review of Policy: Single Person Operations in ATC (SPO)

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Review of Policy: Single Person Operations in ATC (SPO)

43RD ANNUAL CONFERENCE, Hong Kong, China (SAR), 22-26 March 2004

WP No. 166

Review of Policy: Single Person Operations in ATC (SPO)


Shrinking federal budgets and commercial pressures from privatisation are producing a global drive for increased efficiencies in the Air Navigation Systems of the world. Consequently, ANS providers are looking to find increased productivity from ATCOs.

Member Associations with staff shortages and those where the Air Navigation System is still developing may find themselves facing similar pressures. As a result, employers are using a number of different labour practices in an effort to increase the number of aircraft movements handled per person and/or reduce number of staff required to run the system.

Because these practices may affect the health and safety of the ATCOs and the safety of the system, IFATCA must monitor their implementation and effect.

This working paper will address one such practice; the use of ATCOs in Single Person Operations (SPO) and will review appropriate policies.

It should be noted that this Working Paper reflects the realities of the ATCOs working environment and does not mean that IFATCA endorses the use of SPO at all.


Up till 2004 IFATCA’s definition of Single Person Operations reads: SPO can be defined as that period of time when an operational ATC unit is providing service with only one person present on staff, that being the ATCO.

Recent incidents and accidents have shown that SPO are still in use at many ATC working places and are serious elements of safety risks. The presence of other staff does not reduce those risks.

Often SPO are part of historically implemented staffing procedures.

There seems to be a lack of awareness of the effects of SPO in safety management, both on regulator’s and provider’s, as well as on controller’s side.

Effect on the ATS system

A 1996 study into Air Traffic Control by Transport Canada noted:

“Running an operation at its most efficient staffing levels usually means that very little surplus staff is tolerated. Unfortunately, in a safety-critical working environment, redundancy in system components is a requirement, including the human side of the system”

Because workload may increase unexpectedly or uncontrollably, back-up staff should be available on call-in within reasonable time limits to ensure the safe continuation of service. But it should be noted that in case of an aircraft emergency or any other incident/accident it is unlikely that staff could be called in quickly enough to assist in the increased workload in case of SPO. This is a risk that ANS providers and their customers must be willing to take if they use SPO. At the same time it is a strong argument against the use of SPO.

Studies on Safety Cultures in Organisations do show that safety thinking should be integrated in all actions taken by an ANSP.

Effects on ATCOs

Fatigue influences the controller’s abilities and leads to decreased alertness and low motivation.

Increase of fatigue and the level of stress felt by the ATCO in the course of his shift are both detrimental to health and well-being.

Immediate relieve should be available in case of an incident/accident

Further information on the resulting effects of SPO and current IFATCA policy can be found in the following areas of the IFATCA Manual:

Page 4131 Work and Rest Schemes

Page 4221 Stress

Page 4223 Fatigue

Page 4223 Pregnancy


SPO eliminate redundancy in the human element of the ANS system. This can lead to a failure of the whole system should the traffic demand on the ATCO exceed his abilities or would he fall ill.

SPO may be detrimental to the wellbeing of the ATCO by reducing his ability to take normal breaks while at the same time it may increase the level of stress and fatigue under which he is operating. In such cases distraction when performing double separate surveillance tasks becomes an even larger safety risk.

The minimum level of staffing should, for these reasons already, be more than one ATCO.

The use of single controller shifts should be strongly discouraged by MAs, both through their providers as their regulators.

Air Navigation Service Providers (ANSPs) must bear full responsibility for the resulting risks to the system when choosing to use SPO. The ATCO must not be held liable for incidents or accidents resulting from the use of SPO.


That the Policy on page 4112 Para 1.6 of the IFATCA Manual be replaced by the following:

1.6 Single Person Operations (SPO)

‘Single Person Operations (SPO) can be defined as operations where an operational ATC unit is providing service with only one appropriately qualified ATCO on duty’

1.6.1 ‘Rostering Single Person Operations (SPO) shall be avoided. In the unlikely event of unavoidable SPO appropriate measurements shall be taken to ensure that the SPO-situation will be alleviated as soon as possible. Until such time measures shall be taken to mitigate all impacts of SPO such as: traffic regulation, provide breaks, informing neighbouring ATC units. Procedures shall be in place to implement such measures in an efficient way, not increasing the workload of the ATCO’

1.6.2 The use of single controller shifts should be strongly discouraged by MA’s, both through their providers and their regulators.

1.6.3 When providers choose to use SPO, they must bear the responsibility for the resulting risk(s) to the system. The ATCO must not be held liable for incidents or accidents resulting from the use of SPO.


Impact of Shiftwork and Overtime on Air Traffic Controllers: Phase II, Rhodes & Associates, 1996.

Report of a Committee on Regulation of Air Traffic Controllers’ Hours to the Civil Aviation Authority – United Kingdom, 1990.

Fatigue in Air Traffic Controllers: Literature Review Transport Canada, Transportation development Centre, 2000.

Focus on Aviation Safety – Prof. Patrick Hudson, Leiden University, 2002.

BFU/Ueberlingen accident 2002

Tahiti incident 2003

Single Person Operations – Paul Neering, IFATCA Circular June 2003, The Controller 2003.

Last Update: September 29, 2020  

March 24, 2020   1019   Jean-Francois Lepage    2004    

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