Normal Operations Safety Survey (NOSS)

NOSS stands for Normal Operations Safety Survey. It is a method which is designed to capture threats to safety that arise during everyday operations, as they occur. It has been developed in partnership by ICAO, The University of Texas, EUROCONTROL and a number of Air Navigation Service Providers.

NOSS provides a means by which even the safest of organisations can continue to learn how to decrease the risk of future incidents or accidents. It is based on the Threat and Error Management framework, the underlying principles of which claim that routine threats to the safety integrity of the system are constantly being managed by the system before they lead to serious outcomes. The frequency of these threats and the ways in which they are managed are known at a local level by the operators of such systems but this information is often not captured in any structured way by the organisation. NOSS provides and means by which this can be achieved.

Although NOSS is based on observing controllers in their everyday work it is not designed to assess controller performance; rather it is concerned with acquiring and overview of how the system performs.


Aviation is considered to be an ultra safe industry; the number of serious incidents and accidents occurring are among the lowest of the high technology industries that surround us everyday. However, even in these ultra safe industries things happen that surprise us and make us think; how did that happen or, where did that come from? The fact is that even ultra safe industries are not immune from things going wrong.

Sometimes this may be because a procedure that was good in the past is not so appropriate now, or that a random or introduced change upsets a previously well performing operation in an unforeseen way.

Of course, because serious and therefore noticeable events are rare, the individuals in the system may fail to notice that things are drifting toward a less safe state. This is where NOSS can help.

NOSS is designed to identify threats to the safety of the operation and how they are managed. From this information organisations can learn how to improve without having to experience an incident or accident. NOSS can therefore be considered as a safety learning tool, not an incident investigation tool.


  • NOSS will ultimately help you do your job safer and better
  • NOSS helps inform the existing Safety Management System
  • NOSS helps operations learn what they are doing now that keeps them safe.

Added value

Because NOSS captures data on what is done during the routine daily operations it potentially allows a forecast for future failures of the system. It is therefore proactive, providing information about today’s operation, compared with incident investigation which is reactive and looks back.

NOSS can identify practices that both challenge and promote safety. Other parts of the organisation can benefit from this information and perhaps avoid or adopt these practices as appropriate.

How does NOSS work?

The NOSS process begins with data collection in the operational setting. Following this, the data generated is de identified immediately; individuals and their workstations are not traceable from this data or from the subsequent report it generates. Data is examined for inconsistencies and clarity (data cleaning) and then analysed prior to the NOSS report being produced by an independent agency.

Participation in the NOSS process is voluntary and individuals who are the subject of a NOSS observation can stop the NOSS observation at any time and ask for records to be destroyed.

To date NOSS has been piloted in two air navigation service providers. Here are two reactions from people involved in these studies.

During 2006 EUROCONTROL has run 2-3 European NOSS trials aiming to gather experience and provide a possible basis for European wide implementation.

NOSS Support team

Contact us for more information.

+32 2 729 39 51