According to the TEM model of ICAO Annex 1, what defines an 'error'?

The definition of an 'error' according to the Threat and Error Management (TEM) model in ICAO Annex 1 encompasses both actions and inactions by an operational person that cause deviations from expected outcomes. By including inaction alongside action, the definition acknowledges that failing to act appropriately can also lead to errors.

In aviation, both active mistakes (like performing the wrong checklist item) and omissions (like failing to verify crucial information) can have significant consequences. Therefore, the model highlights the comprehensive nature of errors, reflecting the complexity of human behavior in safe operational practices. Recognizing both errors of commission (doing the wrong thing) and errors of omission (not doing something necessary) allows for a better understanding of human factors and enhances training and safety measures in aviation environments.

The other options do not capture the complete definition since they either limit the scope to only actions or imply a moral judgment with terms like "wrong," which detracts from an objective understanding necessary for effective error management in complex operational settings.