Non-pilot subjects were flown in a small aircraft and asked to interpret the artificial horizon after being spatially disorientated. The majority of participants wrongly interpreted the instrument due to feeling the ‘leans’, when our eyes and ears generate confusing signals to the brain.

Key facts

    • Spatial disorientation leading to the ‘leans’ has been recognised as a significant hazard in aviation and there have been several commercial air transport accidents in which it has been identified as a causal factor.
    • 40 non-pilot subjects were flown in the National Flying Laboratory Centre’s Bulldog aircraft, in collaboration with TNO Human Factors and TU Delft in the Netherlands.
    • Subjects were blindfolded while a test pilot flew gentle rolling manoeuvres, then removed the blindfold. The subjects were then asked to return the aircraft to the wings-level position using only the artificial horizon (AH) instrument. 
    • The results suggest that pilots experiencing spatial disorientation, with the incorrect expectation leading to the ‘leans’, are more prone to make an error while attempting to correct the upset using the AH.

Bulldog aircraft in flight 
The NFLC Bulldog training aircraft.

Aircraft cockpit interior 
Interior of the cockpit, showing a) the AI, b) the subject holding the centre-stick and c) the inertial measurement unit.


Impact of our research

Favourably, participants were better able to prevent errors when they took more time before responding. This supports the drive to provide enhanced upset recovery training to help pilots prevent incorrect, intuitive responses.

It may be useful to provide additional advice to pilots to alert them that they have been subjected to a manoeuvre likely to induce spatial disorientation as an aid to upset recovery; this could be based on existing multi-sensory models to predict spatial disorientation events.

This research could also have implications for the design of instruments and cockpit layouts to make it easier for disorientated pilots to re-familiarise themselves with the position of their aircraft.

Why the research was commissioned

Spatial disorientation has been identified as a significant hazard in aviation.

Pilot expectation, startle and upset recovery training are active areas of research following several commercial air transport accidents in which spatial disorientation has been identified as a causal factor.

This work is part of a collaborative programme of work with Visiting Professor Eric Groen from TNO Soesterberg and Dr Annemarie Landman from TU Delft in Holland.

Why Cranfield?

Our National Flying Laboratory Centre (NFLC) aircraft are virtually unique in the global academic sector and are used to support pioneering research, teaching and consultancy.

Cranfield is unique in the world because we have our own runway, our own airport, our own aircraft and our own air navigation service provider.

Facilities used

This study was published in the Journal of Applied Ergonomics. Download a PDF of the paper.