title: Underwater detectibility of a lighting system on a helicopter escape exit.
abstract: BACKGROUND
  When a helicopter ditches into water, it immediately inverts due to the weight of the engines and then fills with water. Locating the emergency exit for escape under such conditions is a difficult task. A new lighting system for an escape exit has been developed that illuminates on contact with water. The detectibility of the lighting was investigated under varying conditions of ambient illumination, water turbidity, and viewing distance.
  
  
  METHODS
  A total of 288 underwater detection trials were carried out by 9 subjects with an illuminated hatch placed at 2 distances (1.5 m and 3.1 m), under 2 ambient illuminations (bright: > 3000 lux and dark: < 0.1 lux), and in 2 conditions of water turbidity. The water temperature was 12 degrees C for all conditions.
  
  
  RESULTS
  At 1.5 m, the lighting system was detectable in less than 1.5 s by all subjects in both clear and turbid water and under both bright and dark conditions. At 3.1 m, the lights were detectable in both clear and turbid water under the dark condition and in clear water under the bright condition. However, the lighting was not reliably detected in turbid water under bright condition.
  
  
  CONCLUSIONS
  The system met original design requirements in terms of detectibility at 1.5 m. The detection time was always under 1.5 s. It could also be detected at 3.1 m in clear and turbid water, under dark conditions. However, the detectibility at 3.1 m in turbid water, under bright condition was less reliable.
authors.affiliation: School of Health and Human Performance, 6230 South, Dalhousie University, Halifax, Nova Scotia, Canada B3H 3J5.
authors.forename: Brendan D
authors.initials: BD
authors.lastname: O'Neill
authors.forename: John W
authors.initials: JW
authors.lastname: Kozey
authors.forename: Chris J
authors.initials: CJ
authors.lastname: Brooks
mesh_terms: D000060:Accidents, Aviation; D000401:Aircraft; D006801:Humans; D008029:Lighting; D014867:Water
chemical_list: D014867:Water