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Published on: October 31, 2011
Detectability of emergency lights for underwater escape
J R Allan1, D H Brennan, G Richardson
1Environmental Sciences Division, RAF Institute of Aviation Medicine, Farnborough, Hants, U.K.
Aviation, Space, and Environmental Medicine
|March 1, 1989
Summary
Underwater escape lighting is unreliable in turbid water beyond 1.5 meters. Visibility is significantly reduced, impacting detection times and reliability for immersed subjects, suggesting design limitations.
Area of Science:
- Human visual perception
- Underwater visibility
- Safety engineering
Background:
- Effective underwater lighting is crucial for safety, especially in emergency situations like aircraft egress.
- Water clarity and ambient light significantly influence the visibility of underwater signals.
Purpose of the Study:
- To quantify the detection time of underwater lights under various environmental conditions.
- To assess the reliability of underwater lighting for emergency egress scenarios.
Main Methods:
- Measured detection times of three underwater lights by six subjects in clear and turbid water (attenuation coefficient = 4.2.m-1).
- Varied viewing distances (1.54 m, 3.1 m), angles (0°, 65°), and ambient illumination levels.
- Compared viewing through a window (simulating a face mask) versus full immersion.
Main Results:
- Lights were rapidly detected (<1s) through a window in clear water.
- No lights were detected at 3.1 m in turbid water.
- Reliable detection by immersed subjects at 1.54 m occurred only in clear water under lower ambient light.
Conclusions:
- Underwater escape lighting design should not exceed a 1.5 m visibility range, especially in turbid conditions.
- An illuminated guide-bar could enhance directional guidance for underwater aircraft escape.
