Visual Contrast Detection Thresholds for Aircraft Contrails

摘要

Twenty licensed pilots participated in a laboratory investigation of visualdetection thresholds for simulated aircraft contrails. Subjects searched a projection screen for simulated contrails while maintaining a prescribed flight profile on a simple flight simulator. Simulated contrails varied in width from 5 arc min of visual angle to 25 arc min, and varied in length from 2 deg to 10 deg. Subjects performed the detection task in an uncued condition, in which they searched an area measuring 135 deg x 37 deg; and in a cued condition, in which they searched an area measuring 45 deg x 37 deg. Detection thresholds decreased with increasing widths and length, however, thresholds were found to be higher than those demonstrated in previous studies. This difference is attributed to the use of a large visual search area and a secondary task. Cued detection, as described above, led to slightly lower detection thresholds. Psychometric functions were drawn that allow the reader to extrapolate the probability of detection associated with contrails of a given size and contrast.