Peter Gibbs President of Survival Systems Training Limited, Dartmouth, NS. Designed course curriculum for Emergency Breathing Systems for both military and civilian helicopter operations. Provided train-the-trainer programs in Aircraft Ditching and Emergency Breathing Systems world-wide for both military and commercial operations. 22 years service in the Royal Navy as a helicopter search and rescue diver and commando helicopter crewman. Commercial divers certificate HSE Part IV (UK), Master Sports Diver ACUC. 31 years in the survival business. email me at peterg@sstl.com ENSURE THAT THE TRAINEES UNDERSTAND THE RELATIONSHIP BETWEEN ALL THREE COMPONENTS.

The Principles of Emergency Breathing Systems for Helicopter Underwater Escape Foster broader knowledge and understanding of the differences between a compressed air breathing system and a rebreathing systems used for helicopter underwater escape.

Helicopter Statistics* In 24 accidents where the cause of death was known 162 fatalities 92 drowned 56.7% of fatalities were the result of drowning (where the cause of death was known). *World Civil Helicopter Water Impacts: Summary of Occupant Injuries. Courtesy Clifford (1996).

Why People Perish Survival will be determined by an individuals’ breath-hold time. Cold shock (Essentials of Sea Survival, Golden and Tipton). Gasp reflex and inability to breath hold.

A Histogram of BHT Under Water in 228 Subjects (Cheung et al, 2001)

The Study Scientific Study. An Investigation of Passenger Evacuation from the Super Puma Helicopter. Brooks, Muir, Gibbs. (March 1999). All participants were underwater escape trainers or divers and each person carried an emergency breathing system for added safety. Study showed under controlled conditions there was a breath-hold requirement of between 23-92 seconds for all subjects to escape. This study proved that there was a need for passengers to carry some form of supplementary air. (Published June 2001, Aerospace Medical Journal)

The Solution Provide some form of air system (3 systems) Rebreather Hybrid Rebreather Compressed Air Based on Self Contained Underwater Breathing Apparatus (SCUBA) Based on breathing air at atmospheric pressure Based on breathing air at atmospheric pressure plus 3.5 litres of compressed air

Types of Systems Compressed Air Demand Valve 1st Stage Regulator Mouth Piece Aluminum Cylinder 3000 psi Low Pressure Hose

Types of Systems Rebreather Securing Strap Mouth Piece and Nose Clip Flexible Hose Red Activating Knob Counter Lung

Types of Systems Hybrid Rebreather Emergency Manual Inflator 3.5 Litres Compressed Air Salt Water Activated Automatic Inflator Securing Strap

Systems Specifications COMPRESSED AIR Working pressure 1800 lbs psi - 3400 lbs Volume 42 litres - 80 litres System weight - approximately 3 lbs. Regulator - first stage Demand valve - second stage Duration of air supply approximately 21 breaths at 21 feet* *based on an average breath volume of 1.5 litres at a breath rate 10.5 bmp with a starting pressure of 3000 psi. REBREATHER/HYBRID Atmospheric pressure Volume = Lung volume + 3.5 litres System weight - 2.25 lbs. Regulator - not required Demand valve - not required Duration - ?

Compressed Air POSITIVE Instant supply of air underwater. Requires no prior activation Duration 2 - 6 minutes Several types available Purge capability Proven in real accidents NEGATIVE Pulmonary over inflation injury Integration difficulties with survival equipment Runs out without warning

Rebreather (Hybrid) POSITIVE Simple design NEGATIVE Complex procedures to follow to make operational during critical part of flight (I.e. ditching) Must activate the system before immersion. No purge capability (cannot be operated under water) Breathing resistance changes with orientation and depth. May be difficult or impossible to breathe at depth. Requires a full breath of air prior to going underwater (rebreather only) Danger of Hypoxia Hybrid Pulmonary Over inflation injury Integration difficulties with survival equipment POSITIVE Simple design

Many Different Systems Integration Many Different Systems Lifejacket Suit Mounted in Aircraft Requires skillful human engineering to match air system to equipment and aviation environment

Flight Commander Leg Mounted Compressed Air System

Brace Position Leg Mounted Compressed Air System (2 point harness)

Compressed Air System Lifejacket/Chest Mounted Using a 4-Point Harness

Leg Mounted Compressed Air System Using a Helly Hansen Immersion Suit

Lifejacket/Chest Mounted Compressed Air System Using a 4-Point Harness

Hybrid Rebreather Using a 4-Point Harness

Hybrid Rebreather Deployed and Ready for Use (Breathing Atmosphere)

Training Requirements All Systems Require: Theory Training Practical Wet Training Practical Underwater Egress Training Approximately four (4) hours

Maintenance Compressed Air System User visual check Recharge 2 year check cylinder and replace O-rings 5 year hydrostatic test if cylinder is greater than 2” in diameter. Hygiene easy Rebreather User visual check Re-pack 5 year replace gas cylinder, operating mechanism, O-rings and swivel elbow Hygiene difficult and time consuming (training only)

Conclusion It is vital to have some form of air system for helicopter underwater escape, especially flying over water below 150C I have discussed the advantages and disadvantages of three systems - compressed air, a rebreather (with no compressed air) and a hybrid rebreather (with compressed air). It is important that the correct system is implemented and that thorough human engineering has been used to integrate the system so it works as advertised. Questions