Inexperienced rescuers may encounter severe problems in an unconscious patient with opening and maintaining a patent upper airway. Designing a ventilating device that could indicate how to open an upper airway correctly may be beneficial. The heads of 102 volunteers were randomly placed in different head positions by one investigator. A pocket mask was then pressed gently on the volunteer's face followed by measurement of the head position angles. Mean (SD) flexion was - 4 degrees (8 degrees) (95% CI - 5.9 to - 2.9); the mean neutral position was 21 degrees (6 degrees) (95% CI, 19.9 to 22.3); extension was 42 degrees (6 degrees) (95% CI 40.8 to 43.0 degrees) and differed significantly between each position (p < 0.001). The flexion and neutral position angles were significantly greater in men than in women: - 2 (7 degrees) vs. -8 (7 degrees) and 22 (7 degrees) vs 20 (5 degrees); p < 0.001 and p = 0.03, respectively. Maximum extension of the head in both supine men and women was 42 degrees, which could be utilised to optimise assisted ventilation of an unprotected upper airway.