Flight display dynamics and compensatory head movements in pilots

Area of Science:

• Human Factors
• Aerospace Physiology
• Neuroscience

Background:

• The optokinetic cervical reflex (OKCR) helps pilots maintain head alignment with the horizon during flight.
• Understanding how visual references influence OKCR is crucial for flight safety and display design.

Purpose of the Study:

• To investigate whether altering the visual reference frame on a flight display affects the optokinetic cervical reflex (OKCR).
• To determine if pilots' spatial orientation reference shifts from the horizon to the aircraft symbol under different display conditions.

Main Methods:

• Eight subjects, including rated pilots, flew in a simulated cockpit under visual meteorological conditions requiring frequent aircraft banking.
• Pilots' head tilt was analyzed using conventional regression against aircraft bank and an event-based analysis of head movements relative to turns.
• Three display configurations were tested: Inside-Out, Frequency-Separated, and Outside-In.

Main Results:

• Head tilt correlated with horizon tilt in Inside-Out and Frequency-Separated displays, but remained level in the Outside-In condition.
• Event-based analysis revealed anticipatory head movements favoring the direction of the imminent bank in Inside-Out and Frequency-Separated conditions.
• A significant interaction (p < 0.001) was found between display condition and aircraft bank regarding head tilt.

Conclusions:

• The horizon is a primary spatial reference, but pilots can temporarily shift their reference to the aircraft symbol.
• Anticipatory head movements, preceding the OKCR, can occur in response to changing visual references in flight displays.
• These findings have implications for flight display design and pilot spatial orientation.