Head position of helicopter pilots during slalom maneuvers.
BACKGROUND
Pilots typically tilt their heads when executing coordinated banking turns, a phenomenon commonly attributed to the putative opto-kinetic cervical reflex (OKCR). The OKCR is usually described as a reflex, primarily driven by stimuli in the visual periphery, and is important to a pilot's spatial orientation by providing a relatively stabilized horizontal frame of reference. The present paper presents an alternative hypothesis for the observed head tilting seen in pilots.


METHODS
An archived data set, originally collected for other purposes, contained the head turn, pitch, and tilt of 4 helicopter pilots recorded at 10 Hz as the pilots executed 42 slalom maneuvers in an AH Mk 7 Lynx helicopter under visual flight conditions. The analytic method was a correlational analysis of head turn, pitch, and tilt.


RESULTS
As expected, pilots routinely tilted their heads during the slaloms in a fashion typically attributed to the OKCR. Correlations among head turn, tilt, and pitch showed that when the helicopter turned left, the head, presumably to look into the turn, turned left and also pitched up and tilted right. Similarly, when the helicopter turned right, the head, presumably to look into the turn, turned right, pitched up, and tilted left.


CONCLUSIONS
The head tilting usually attributed to a neuromuscular reflex driven by visual stimuli may be a biomechanical consequence of the head posture pilots assume when they simply look where they are going, eliminating the need to postulate the existence of a novel neuromuscular reflex.
Temme
Leonard A
LA
U.S. Army Aeromedical Research Laboratory, Aircrew Health and Performance Division, Fort Rucker, AL 36362-0577, USA. leonard.temme@se.amedd.army.mil
Still
David L
DL
D000328:Adult; D000401:Aircraft; D001359:Aviation / Q000379:methods; D001696:Biomechanical Phenomena; D006257:Head / Q000502:physiology*; D019416:Head Movements / Q000502:physiology*; D006801:Humans; D008297:Male; D010865:Pilot Projects; D011187:Posture / Q000502:physiology*; D012027:Reflex, Vestibulo-Ocular / Q000502:physiology*; D013037:Spatial Behavior / Q000502:physiology*; D006113:United Kingdom; D014481:United States; D014785:Vision, Ocular / Q000502:physiology*