Underwater disorientation as induced by two helicopter ditching devices

Area of Science:

• Human Factors and Ergonomics
• Aerospace Medicine
• Vestibular Physiology

Background:

• Spatial orientation relies on integrating visual, vestibular, and somatosensory cues.
• Underwater environments degrade somatosensory and visual cues, while making vestibular cues ambiguous.
• This disorientation poses a significant risk to emergency egress after helicopter ditching.

Purpose of the Study:

• To compare the degree of underwater disorientation induced by the Modular Egress Training Simulator (METS) and the Shallow Water Egress Trainer (SWET).
• To evaluate the effectiveness of these simulators in familiarizing aircrew with underwater egress scenarios.

Main Methods:

• 36 healthy subjects participated in a repeated measures design.
• Quantified disorientation by measuring subjective vertical pointing deviation, time to egress, and subjective reports.
• Compared disorientation across three seat positions: SWET chair, METS window, and METS aisle.

Main Results:

• Both METS positions induced significantly higher disorientation ratings and worse ease of egress compared to SWET.
• Subjective vertical-pointing accuracy was significantly poorer in METS than SWET.
• Time to egress was significantly longer from METS positions than SWET.

Conclusions:

• The METS device effectively induces underwater disorientation relevant to simulated helicopter ditching.
• METS is a valuable tool for aircrew training in managing underwater egress challenges.
• Findings highlight the importance of simulator fidelity in replicating real-world disorientation scenarios.