Undesired aircraft state

[Ref SKYbrary, Airbus FAST magazine, FAA AC 120-90]

What’s an undesired aircraft state?

According to FAA doc:

Undesired aircraft state – a position, speed, attitude, or configuration of an aircraft that:

  • results from flight crew error, actions, or inaction; and
  • clearly reduces safety margins

Undesired aircraft state can be managed effectively, returning the aircraft to safe flight, or the crew action or inaction can induce an additional error, incident, or accident.


According to Airbus publication:

An undesired aircraft state is characterised by unintentional divergences from normal operating parameters. It may involve pitch and/or bank angle divergences, as well as inappropriate airspeeds for the conditions.

Deviations from the desired aircraft state will become greater until action is taken to stop the divergence. Return to the desired state can be achieved through the aircraft’s static or dynamic stability, auto-flight system response or pilot intervention.

Airbus believes that flight crew engagement combats complacency through active monitoring.

This makes active monitoring critical in ensuring awareness and avoidance of undesired aircraft states and provides the strongest counter-measure against startle**. An engaged crew is in the best position to cope with undesired aircraft states.

From the early stages of training, pilots should acquire knowledge, skills and attitudes to perform active monitoring throughout all operations and phases of flight.



As defined by ICAO, “startle” is the initial short-term, involuntary physiological and cognitive reaction to an unexpected event that commences the normal human stress response.


#What’s #undesired aircraft state

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