Preliminary Study of the Implementation and use of Emergency Breathing Systems (CAA Paper 2003/13)

Abstract

Summary

The primary aim of this study was to establish the extent of knowledge and testing performed on various forms of emergency breathing system (EBS). Issues and concerns were reviewed, highlighting gaps in the current knowledge.

Published data on helicopter water impact accidents was analysed to determine the frequency of different impact conditions and the incidence of drowning. The high incidence of drowning is largely due to cold shock, which greatly reduces breath-hold time and thus limits the time available for escape. EBS are designed to help overcome cold shock by allowing individuals to breathe underwater for a short time, thus extending underwater survival time. In this way EBS can provide a means of bridging the gap between maximum breath-hold time and escape time, and thus reduce the incidence of drowning.

Consideration of the different types of helicopter accident has led to the conclusion that emphasis should be placed on the deployment of EBS after landing on water, but before submersion. Underwater deployment should only be attempted if escape would otherwise be impossible.

Whilst it was considered that reliance on EBS for escape should be minimised, it has been shown that successful use of EBS can reduce the levels of stress experienced during helicopter escape under simulated conditions. That said, satisfactory performance of EBS is dependent upon good design, reliability of the equipment, ease of use and performance on demand. Other key factors include human individual capabilities, training, environmental conditions, helicopter design and the features of the helicopter accident.

In order to maximise the benefits of EBS and minimise the risk of human error during deployment and operation, training is required. Such training should include both classroom and practical sessions (dry and wet), with a progressive development of knowledge leading to competence and confidence in the use of EBS. It was also considered important that competence be maintained to prevent any potential failure of deployment.

When reviewing current knowledge on EBS equipment, particular attention was given to the testing and development of two products, one being a re-breather and one a compressed gas system. The background and rationale behind their selection are discussed. Established performance criteria and problems encountered during the development of these and other products provide a basis for the approval and selection of future products.

Based on this knowledge, an example technical standard for emergency breathing systems has been drafted. The draft example standard identifies minimum performance requirements to ensure that equipment is manufactured to consistent and satisfactory standards, and that basic health and safety requirements are met.