Background: The majority of Dutch F-16 pilots experience in-flight oxygen mask related nasal discomfort and injury. We aimed to analyze the fit of the oxygen mask. Methods: We successfully scanned 35 pilots with a 3D scanner to measure the distance between the contact area on the nose and the oxygen mask in seven points, and the difference (Δ) in angle between the nose and the mask relative to the facial midline. Ill fit was defined as ≥ 4 mm distance, or Δ ≥ 4o angle. Intraclass correlation coefficients were used to objectify the reproducibility of the measurements. Results: There were 35 pilots who had ≥ 4 mm distance between the nasal dorsum and the mask and 14 pilots had Δ ≥ 4o angle. Reproducibility of the distance measurements was excellent (R ≥ 0.93, CI 95% 0.86-0.96) and of the angle measurements was good (R = 0.72, CI 95% 0.5-0.8). Conclusion: The room for displacement that we found may be a contributor to the discomfort. It is indicative of an ill fit of the oxygen mask, since all subjects had complaints. We recommend evaluating whether improved fixation of the mask and simultaneous reduction of the pressure on the nose will improve comfort.