Minimum Hours in Position

Minimum Hours in Position


Holders of air traffic controller (ATCO) licenses are usually required to have exercised their privileges for at least a specified minimum of hours in order to have their license revalidated.

Erosion of ATCO knowledge and skills is a natural process which is normally addressed by refresher training. However, maintaing the necessary level of competence (and especially the practical aspect thereof) is particularly challenging with some groups of license holders:

  • Administrative personnel. Managers and ATM experts sometimes choose to retain their ATCO licenses although their main job may not require this.
  • On-the-job training instructors (OJTIs). While performing their duties in live environment in the ops room, they are not actually practicing their controller skills.
  • Holders of several ratings and/or endorsements, e.g. a person that can work at a tower, approach and area control or one that is endorsed for all sectors of a large and complex ACC (area control centre) containing several groups of sectors. A controller being allowed to work at three different positions will have 1/3 of the hours (at best) for each of them compared to a colleague who only has one option. A similar issue arises with shift supervisors, many of whom are active air traffic controllers as well.
  • Holders of ATCO license that additionally perform other tasks outside the ops room, e.g. instructors in a simulator, theoretical instructors, conducting simulations, etc.
  • A combination of the above.

Associated Issues

All the cases described in the previous section are generally beneficial to the ATM system. Combining the expertise and experience from different (but relevant) fields can synergise and produce excellent results. For example, an ATM expert designing procedures or airspace features may experience them first-hand as an end-user as well. An instructor in theoretical training can enrich the training by adding current situational examples or identify gaps in the training process. On the other hand, special care must be taken to balance the two worlds so that safety is not compromised. The primary risks are:

  • Not being there. If a person is currently acting as a controller but his primary occupation is something else it is possible that their mind remains focused on tasks other than the provision of ATS, especially in situations that seem like low or medium workload. Such circumstances are conductive to complacency and human error and may eventually contribute to an incident.
  • Erosion of practical skills. Sector and unit capacity definitions are based on the assumption that controllers are able to execute routine tasks in an expeditious manner. Therefore, a person that only seldom works in the ops room (or in the tower) may find it more demanding to perform e.g. simple interactions with the ATM system. This may, depending on the circumstances, result in the person being overloaded with traffic that could have been safely handled by a regular controller that only works at that position.
  • Not being up to date. The ATM environment is constantly evolving. While it may sometimes appear that this happens at a slow pace, the truth is that small changes, such as an updated letter of agreement, new sectorisation or a new/updated procedure appear quite frequently.


The issue with a person "not being there" can be dealt with at both organisational and personal level. The organisation must establish procedures and distribute tasks in such a way that people are provided enough time and resources to complete them, meaning they do not have to work "in background mode" while providing air traffic services. On a personal level, it is a matter of self-discipline to focus on the tasks at hand. Unfortunately, there is no formal, measurable way to address this issue.

On the other hand, both erosion of skills and not being up-to-date can be mitigated by placing a formal requirement for minimum hours, i.e. to exercise the licence privileges every so often. Many countries have strict rules about this. Additionally, the following factors may be considered:

  • The basic problem may be more related to individuals than to the system. This makes it especially difficult to design indiscriminate procedures.
  • Reducing the number of unit and sector endorsements is a step to consider. While working interchangeably between a tower and approach units at the same aerodrome (or a tower and ground) is perfectly acceptable and adding a degree of flexibility, adding endorsement for ACC sector(s) or supervisor duties to those may prove to be too much. This is especially true for people who combine office work with being a controller.
  • Regular competence checks or the introduction of continuous assessment are a good preventive tool.
  • Studying recordings of RTF exchanges with an instructor will help to detect errors in phraseology.

In the European Union, the procedures for maintaining and assessing controller competence are described in the Unit Competence Scheme. This is a document that is required so that the unit complies with Regulation 2015/340 and contains, among other things:

  • A minimum of hours for exercising the privileges of the unit endorsement within a defined period of time, which does not exceed 12 months (but can be shorter, e.g. 6 or 3 months). It is also possible to define several minima, e.g. a quarterly and a yearly one. If the requirements are not met, appropriate remedial procedures are defined, e.g. simulator training, supervision by an OJTI, assessment procedures, etc.
  • A maximum continuous period (90 days at most) when the privileges of a unit endorsement are not exercised. If this period is exceeded then appropriate procedure is executed for competence assessment and/or training. It is acceptable to define different procedures for different situations. Generally, the longer the period is, the more training will be required. It is possible, however, to prescribe the necessary training based on e.g. simulator assessment.
  • A special provision defining how the OJTI's time spent instructing is to be counted in this regard. The Regulation sets an upper limit of 50%, meaning that, at most, half these hours are treated as being in position. Note that if an OJTI instructs trainees in a simulator, this is not counted towards the minimum required hours.

A Real Life Scenario

This section describes a real-life situation which was discussed at a meeting of the EUROCONTROL Safety Improvement Sub-group (SISG). Details have been changed to preserve anonymity.

He was working at the Area Control Centre in Hightown, he was just back after a meal break and still had a few hours before he could return home. The last few months had been interesting, his new project was going well, but he also enjoyed the few days a month he worked operationally as a controller. As it was almost 15 years since he last worked 100% operationally, he never considered returning to operational life full time; it simply did not interest him. This was the second day he had worked operationally this month, the last time was three weeks ago; he did not really bother.

He saw the conflict well in advance; the two aircraft were not exactly on opposite tracks, but close enough for him to realize that he should do something. With his long operational experience he had done this thousand of times before; he would adjust the heading of one, or if necessary, both of the aircraft. Why it went wrong this time he could not really explain afterwards; neither could he when it happened again two months later. He did give the pilots new headings but not enough; in both cases the conflict resulted in a loss of separation.

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