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NOSS Results

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Category: Safety Management Safety Management
Content source: ICAO ICAO

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


As NOSS is a diagnostic tool only, it provides an overview of the “TEM strengths and weaknesses” of the ATC operations observed, but it does not provide any remedies or solutions for problem areas that may have been identified. In that respect the NOSS report is the start rather than the end of a safety management process. The ATS organisation receiving the report must act on the findings presented in it for the report (and thereby the NOSS project) to have any noticeable effects on safety in the organisation.

Interpreting the Report

The ICAO NOSS Manual advises on cautionary presentation of the NOSS report to the organisation by stating that: “The NOSS report contains a significant amount of statistical data that are best interpreted by someone having a firm understanding of the underlying theoretical foundation established by the TEM framework to ensure effective insight into, and consensus on, safety trends and to avoid potential misinterpretation.” For example, certain patterns of errors may be interpreted as reflecting non-standard practices of a particular group, when in fact the patterns of errors are highlighting some aspect of the operational environment (e.g. airspace design, procedures) that is leading to such errors. For this reason it is unwise that the raw statistical data be released for general consumption. It is more useful if information from the report is used for specific briefings at an appropriate level for each of the projected audiences. This does not mean that information should be excluded or added for specific groups, but rather the style and level of the presentation should be varied. The most logical persons to prepare and present those briefings are the project manager and the facilitator (if applicable). It should be highlighted at all briefings that while formally the delivery of the report is the final outcome of NOSS, it also is the starting point of a safety management process that will evaluate the report findings in conjunction with other information sources within the organisation. It should also be stressed that not all findings highlighted in the report will necessarily be acted on, particularly when the level of risk they pose can be adequately managed.

Targets for Safety Enhancements

The recommendations from the NOSS report will indicate targets in the organisation for safety enhancements. Yet it is up to the organisation to determine which changes are going to be made and at what moment in time in the operational processes. The NOSS recommendations can be integrated with those from other elements of the safety management system in the organisation, e.g. incident investigation or voluntary reporting systems. By doing so it is likely that the organisation will apply its resources in the best possible way to enhance safety in its operations.

Guidance on which targets to select first is difficult to provide for it will depend greatly on the particular circumstances of the operations of each ATS provider. Threats that occur infrequently but are often mismanaged would be a category of potential targets. However this applies similarly for threats that occur frequently and are generally well managed, e.g. runway crossings by tow aircraft and/or service vehicles. Even though the crossings appear to be well managed by the ATC crews, close attention of the controllers is required each and every time the runway is crossed. By constructing a taxi track or service road around the runway, the threat can be removed (or its frequency of occurring reduced), thus making the operation more safe and potentially increasing the runway capacity at the same time.

Scheduling a Follow-up NOSS

After a NOSS has been conducted, the results of the report have been analysed and processed by the ATS provider and appropriate safety changes have been proposed and implemented. NOSS can be used as a tool to measure the effectiveness of the changes made. To that end a follow-up NOSS can be conducted on the same target(s), and the results of this second NOSS can be compared with those of the first one. It is recommended to allow an adequate time span between successive NOSSs with the same target(s), in order for safety changes to take effect before they are re-measured.

For a follow-up NOSS the same preparations are required as for a first NOSS (e.g. the publicity phase, observer selection, observer training), even though the same individuals may be involved. Since participating in a NOSS is not a part of an everyday routine, an individual’s skills and knowledge about the process will have faded and need to be re-built just as carefully as the first time.

Once a NOSS project has been successfully concluded, the ATS provider may decide to conduct another NOSS at a different location and/or with a different target (which could be a smaller element of the first NOSS). There is no need to wait a number of years to conduct this “new” NOSS, for it will constitute a “first” for the location or target where it is conducted. If a sufficient number of different locations and/or targets can be selected, an organisation can design a multi-year NOSS programme that successively covers the operations in periodic cycles.

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