TEM is a conceptual framework that aides, from an operational perspective, in understanding the interrelationship between safety, human performance and the dynamic and challenging contexts in which ATM duties are performed. The TEM framework is sensitive to the interplay between the operational environment and human performance, and the resultant impact on human performance.
Threats are defined as external events or errors outside the influence of the controller, but which require his or her attention and management if safety margins are to be maintained. Threats are everywhere (traffic, adverse weather, airport/airspace infrastructure, equipment, pilots, other controllers, etc.) and controllers must devote attention to managing them. The more complex, challenging, and/or distracting the environment is, the greater the controller’s workload.
Controller errors are defined as observed deviations from organizational expectations or controller intentions. Errors can vary from minor deviations, such as not using a checklist, to something more severe, such as not coordinating an altitude change with other controllers. Regardless of cause or severity, the outcome of an error depends on whether the error is detected and managed before it leads to a consequential outcome. This is why the foundation of TEM lies in understanding error management rather than solely focusing on error commission.
Undesired States (USs) may occur as a result of threats or errors that are not properly managed. Undesired Sates are more difficult to define, but involve a clear reduction in safety margins and may be thought of as pre-cursors to incidents.
The Threat and Error Management (TEM) framework has been used widely in aviation:
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