Increasing Altitude and the Optokinetic Cervical Reflex

Area of Science:

• Aerospace Medicine
• Human Factors Engineering
• Neuroscience

Background:

• The optokinetic cervical reflex (OKCR) is a pilot's reflexive head tilt in response to aircraft banking, aiming to stabilize the horizon.
• Visual cues and the surrounding environment change significantly with altitude, potentially impacting spatial orientation.
• Limited research exists on how increasing altitude affects the OKCR.

Purpose of the Study:

• To investigate the effect of altitude on the optokinetic cervical reflex (OKCR) in pilots.
• To test the hypothesis that higher altitudes decrease the OKCR due to altered visual cues.

Main Methods:

• 16 subjects participated in flight simulator sessions at two altitudes: below 1500 ft and above 15,000 ft.
• Head tilt, aircraft altitude, and bank angle were recorded during simulated flights.
• Statistical analysis using two-way ANOVA with Bonferroni post hoc tests was performed.

Main Results:

• Aircraft bank consistently elicited head tilt in the opposite direction at both low and high altitudes.
• A statistically significant reduction in head tilt (86% of bank angles) was observed at high altitude compared to low altitude.
• The magnitude of head tilt was smaller at higher altitudes for equivalent bank angles.

Conclusions:

• The study demonstrates a discernible difference in the OKCR between low and high altitudes.
• Pilots exhibit a diminished head tilt response at higher altitudes.
• Further research is needed to elucidate the underlying mechanisms and consequences of this reduced reflex on pilot orientation.