Airservices—Is it OK to EXPECT?

image: Airservices

The old adage, ‘never assume anything in Air Traffic Control’ is as relevant today as it was 40 years ago.

Controllers do base operational decisions on an expectation that a pilot will comply with control instructions every day.  It is reasonable for this to occur however what is important to ALWAYS remember, is that those reasonable expectations are still in fact ASSUMPTIONS.

It is imperative therefore, that an effective and continuous scan is employed, which becomes a great defence towards assurance that those reasonable expectations are being realised and that the plan based on those expectations is appropriate and achieve the desired intent.

Expectation bias however, is a very powerful human condition when an individual’s expectations about an outcome influence perceptions of one’s own or others’ behaviour.  As a result, this bias can erode the skills and techniques ‘normally’ applied to assure safe and efficient air traffic services to the point where safety margins are infringed.

Airservices has identified that a significant number of occurrences are influenced by expectation bias. Awareness of the influence expectation bias can have on your ability to perform ATC, is an important step in mitigating the condition from developing.


  1. Did some manager with a degree think up “expectation bias”? Saying it is a condition that needs mitigating is a load of rubbish that can be replaced with one word. CONCENTRATE.
    If pilots didn’t expect the nose to rise and speed to decrease when the pulled back on the stick, they would never learn to fly. We check the controls pre-flight. So if this fails to happen in flight, there is a very serious reason, which would have been taught, if not practised in training.
    What worries me is that the computers or autopilots are so complicated that the captain often doesn’t know who is flying the plane.

  2. What all these so called bias fairytale stories fail to realise is that we are dealing with HUMAS here on both ends of the string jam tin communication system! We can make a 100 airframes exactly the same, you will never make a 100 pilots and or controllers the same! With a constant commercial pressure on pilots flying for a living the system will be broke for all time, get used to it!

    • There is technology out there now, like Block Chain technology and digital datalink comms which are perfectly suited to an improved Air Traffic Services System, including ATC and now with a system backup of similar capacity to GPS/ Satellite/ Datalink based systems. There should be a revolution but politics will stop that ..

  3. One historical example is 1978 accident between C172 and B727 at San Diego. Expectations were for the B727 crew on approach – to have a clear straightforward run in with nil PCAs from other aircraft.

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