Preparing for NOSS

Preparing for NOSS

Note: This article is entirely based on the draft ICAO NOSS Manual.


Organising for NOSS

When an ATS provider starts the preparation for conducting Normal Operations Safety Survey (NOSS), one of the first steps towards advancing the survey is that the management should seek and receive support from the controllers’ workforce and their representing associations and unions.

Consideration should be given to the establishment of a project steering committee to oversee the preparation, implementation and follow-up of a NOSS in the organisation. The steering committee is typically comprised of the NOSS project manager, a representative from the controllers' association, a management representative and a representative from the operational environment (e.g. a supervisor). One of the tasks of the steering committee could be to plan and design the NOSS promotion campaign as part of the project management plan.

The project steering committee is also the logical platform to address whether or not the organisation needs the services of an external NOSS facilitator and/or a data analyst for the NOSS project. If it is the first time that a NOSS is being conducted in the organisation, chances are that external services will be required. However for an ATS provider that has prior experience conducting a NOSS, this expertise may already be available in the organisation.

The project manager is the person to elicit the support for the NOSS project from both management and the controllers' association. The project manager organises briefings for different levels of management as required, to assist in setting the organisational expectations for the NOSS project. The project manager organises the resources for the NOSS project, promotes the project within the organisation and in general acts as a troubleshooter for the duration of the project. In the data collection stage the project manager may also be responsible for rostering the observers. The project manager should be responsive to observer needs and act quickly to resolve any issues that may arise.

International Civil Aviation Organisation (ICAO) recommends that, prior to conducting NOSS, a careful designed promotion campaign will facilitate the controllers' understanding of the purpose of the survey. The NOSS project should be communicated and made transparent to the workforce.

Target Selection

For most ATS providers, conducting a NOSS in the entire operational environment will not be feasible as NOSS is designed to capture data in a selected part of the operation over a limited period of time. Therefore an ATS provider should determine early on in the project which specific part of the operation will be the target for the NOSS.

A NOSS that covers a large array of operations may highlight more general issues, but by focusing on smaller units of analysis (e.g. conducting a NOSS within an ACC as opposed to across multiple ACCs), more detailed information about the operating environment will be captured. Results from earlier trials indicate that organisations that do not try to cast too wide a net can maximize the information derived from the NOSS that can be used during the safety change process.

After conducting a NOSS in a specific area of the operation an ATS provider may decide to target a different area for another NOSS, thus potentially covering the entire operational environment over a number of years.


Once the NOSS target has been selected, the next item to decide on is how many observations will be required in order to obtain a representative view of the normal operations in the target area. If too few observations are conducted, it will be difficult to be sure that the data collected are representative of operations. Important trends may be overlooked and, as a result, the information in the final report will be diluted. On the other hand, if too many observations are conducted, this can affect the motivation of the observers and the observed alike, and it will take longer for the NOSS report to be completed.

In order to determine how many observations are appropriate, it is necessary to consider the scope of the NOSS. The number of working positions in the towers, approach and/or area sectors to be included in the NOSS should dictate the number of observations conducted. For example, if a NOSS is scheduled in a tower environment with one ground control position and two runway control (or air control) positions, a representative sample could be obtained by conducting 30 observations on the ground control position, and a total of another 30 observations on the two runway control positions. (Assuming that the two runway control positions are of equal complexity and workload, the observations can be divided 30-0, 15-15, or 0-30, just to give some examples, as long as the required total number is reached.) In a smaller tower with only one controller plus an assistant, a representative sample could probably be obtained by conducting 40 to 50 observations of the controller position.

If a NOSS is being conducted in an ACC with five groups of sectors, 25 to 30 observations would be conducted on each group, equally distributed amongst the sectors in that group.

It is to be expected that during the data collection period some observations will have to be terminated as a result of operational developments at the working position or, for other reasons, will not result in a usable observation report. Therefore the total number of scheduled observations should be 5 to 10 per cent higher than the minimum number of observations required to produce a valid NOSS project report.


When considering the very first preparatory activities for a NOSS as the starting point, and the delivery of the final report as the end point, the duration of a NOSS may be anywhere between 6 and 9 months. This period however will most likely be experienced as such only at the NOSS project management level. For the operational staff in an organisation, the starting point will probably be perceived to be the first day of the data collection phase. Therefore, to the operational staff, the duration of the NOSS project will appear to be in the order of 2 to 4 months, depending on the time required to analyse the data and prepare the report.

The duration of the data collection period is to a large extent determined by the number of observations that need to be scheduled. As a general guideline though it is recommended to collect the data in a period of one or two months, in order to provide flexibility in rostering observers, prevent observers from becoming fatigued, prevent the observed staff from tiring of the constant presence of observers, and capture data over a wider time frame which will provide a more representative depiction of the operation. During this period the collection of data is not necessarily a continuous process, i.e. the NOSS observations do not have to take place every day in this period. If data were to be collected over a period longer than two months, however, there is a risk that organisational momentum and focus may be lost.

Timing for the NOSS

Consideration must also be given to where the project fits in with other ongoing activities and developments in the ATS organisation. If new equipment has been commissioned, or major changes in procedures are being implemented, that is probably not a good time to conduct a NOSS. On the other hand, if a period is foreseen in which there will be a relative surplus of staff available, this might be an excellent opportunity to schedule the data collection phase of a NOSS. No all-encompassing guidelines are available for deciding on the time frame, except that the NOSS project steering committee would seem to be the logical platform for this discussion.


One of the NOSS trials was held in a State where English is not the first language. This did not present any problems since the level of conversational English within the observer group was high. However, it was suggested after the trial that perhaps the observer reports might have been of an even higher quality if they could have been written in the native language of the participants. Any ATS provider can of course opt to conduct a NOSS in the local language, as long as it is realised that a decision to translate the NOSS supporting material may have implications for external support, coding and potentially also for benchmarking of the NOSS results with other organisations.

Briefings of Affected Groups

Briefings provide both an ideal opportunity to explain the NOSS concept and a forum to identify unforeseen issues and answer questions. Each briefing should be carefully planned to ensure a logical flow of information that focuses on the needs and requirements of each particular group. At each briefing ample time should be allowed for questions and discussion on key issues.

The content of each briefing needs to be tailored to each group's needs; however, there are a number of generic items that should be included in all briefings:

  • the purpose of the NOSS and the intended outcomes;
  • where the NOSS process fits into the organisation's Safety Management System;
  • the extent of the planned NOSS including the locations to be observed and the timeframe for the NOSS;
  • an explanation of the NOSS operating characteristics; and
  • the name and contact details of the project manager for any queries or issues that may arise in relation to the planned NOSS.

According to ICAO there are several groups whose support is critical for the NOSS that should receive specific and tailored briefings. These groups are: senior management, staff representatives/unions groups, operational managers; supervisors, general staff.

Correctly managed briefings that promote this philosophy will greatly improve the likelihood of a successful NOSS. Preparation and planning are the keys to success in this area and if correctly executed will result in an informed organisation that is prepared and willing to participate.

Selection of Observers

During the data collection period, which to the operational staff in an ATS provider is the most visible part of a NOSS, the role of the observers is more than just that of collecting the data. Because of their proximity to the staff at the operational positions, the observers also become the “face of NOSS” in that period. Even though observers are not expected to interact with the controllers they observe, it is inevitable that some questions will be asked by the operational staff before the observation is conducted, or immediately after.

Those interchanges are usually about the purpose of the observations, or the NOSS methodology in general, and may contribute significantly to the understanding and acceptance of the observation process by the workforce. It is therefore prudent to keep that aspect in mind when selecting the candidate observers for a NOSS.

Attributes of suitable candidates to be selected as NOSS observers include:

  • Professional credibility and trust;
  • Analytical quality;
  • Open-mindedness;
  • Motivation;
  • Sound judgement.

Observers who are not rated at the working position they observe usually produce better reports than observers who are rated at that position. An explanation for this may be that rated observers tend to become absorbed in the technical details at the working position more than non-rated observers do. Non-rated observers, in contrast, tend to focus more on the situation as a whole at the working position, which in essence is what a NOSS is looking for.

Observers’ “Code of Conduct”

There are generic guidelines that must be kept in mind when formulating rules of conducting the NOSS:

  • The observers must be as unobtrusive as possible during observations.
  • The observers are not there to assess the performance of individual controllers.
  • The observers should not interfere with the ongoing operations unless safety is clearly about to be compromised. (This situation may be compared to an on-the-job-training situation, where the instructor has to decide to what stage a situation can develop before an intervention is necessary.) An observer should not permit a traffic situation to degrade to the point where safety is compromised. The observer should give the controller(s) a reasonable opportunity to manage and resolve the situation. If it appears however that the situation will not be resolved in time, the observer is expected to bring the situation to the attention of the controller. This action will show that NOSS observers will not let safety be jeopardized and that they will provide an additional defence for the controller while present.
  • If an incident should occur during a NOSS observation, conventional incident reporting mechanisms are expected to prevail. The observation will cease and the data will not be used for NOSS purposes.
  • If a controller declines to be observed, the observer should simply withdraw. The observer should inform the project manager at the earliest convenient point about this and, if known, provide any rationale as to why the controller may have refused. While it is not necessary for the project manager to know the identity of the controller who has refused, it is important that the project manager determine if this was merely an isolated event or if the refusal was due to a bigger issue such as a lack of understanding of the goals of NOSS or a miscommunication. With this knowledge, the project manager will be able to decide on remedial actions when appropriate.

Data Handling (Storage and Protection)

For the integrity of the NOSS process, it is essential that the data be protected from inappropriate use. Solutions that may be worth investigating in this respect include the creation of an independent body (nationally or regionally) for the storage of the data, or storing the data in an institution that is not legally bound to make information available to the public (e.g. a university or a research laboratory).

Receiving the Report

While areas of strength are easy for the organisation to accept, areas of unexpected weakness can potentially cause an overreaction if not properly managed. The NOSS report is merely a diagnostic overview of what is occurring during normal operations and does not indicate solutions. For meaningful safety change to occur, the organisation must determine why particular patterns of threats, errors and undesired states are occurring.

To ensure that the maximum benefit is gained from a NOSS report, the organisation must prepare well in advance. At that stage the following points should be considered with the final report in mind:

  • What does the organisation hope to achieve from NOSS? The organisation must be clear about the outcome that is sought and be confident that their expectations are realistic.
  • Is senior management prepared for unexpected and possibly undesired findings?
  • Do any groups within the organisation have strong negative agendas that could be boosted by the NOSS findings? The NOSS findings should always be seen as enlightening to all levels of the organisation and never as a political tool.
  • Is the organisation prepared to share all findings, good and bad, with staff?
  • Is the organisation committed to addressing issues highlighted by the NOSS?

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