Are We Sure Marine Escape Chutes Work?

Ships, cars and airplanes are all quite reliable, but since they move and occassionally behave in unexpected ways, it is necessary to provide emergency systems to protect passengers or crew, or allow passengers and crew to escape.

There are many such systems like seatbelts, air bags, escape slides, life rafts and life boats. The design and operation of such systems is always complex and often includes complex trade offs and, due to the inherent safety of boats and airplanes, only allows limited actual testing. Some systems are incredibly cost effective (seatbelts) others are effective, but carry high additional costs and can be questioned with regard to cost and safety effectiveness (such as air bags).

Marine evacuation systems (MES), and particularly marine evacuation chutes belong in that latter category and this blog raises some issues we have encountered.

When systems such as airbags and MES are actually called on during an emergency, they already have incurred an operational history that impacts their ultimate effectiveness in the form of the cost they incurred (including the cost of injuries) prior to their use in the emergency.

In cars the ever increasing thickness of the A pillar (the posts on either side of the windshield) due to roll over standards and the inclusion of side airbags, is now starting to create a visual obstruction to an extent where I am starting to question its safety in turns. Especially with regard to pedestrians at pedestrian crossings. If we add large mirrors that are placed immediately behind these A pillars, and high driving positions as found in large SUV’s, there is a visual obstruction that is an accident waiting to happen. Almost perversely, in that case the airbag that is fitted in the A pillar and the roof strength is of no benefit to the pedestrian that is run down on the sidewalk and we are dealing with a very dubious safety trade off. (I can go on with this subject, bizarrely, cars still need to be designed for people that do not use seatbelts. Nuff said.)

In maritime there appears to be a dubious solution to passenger and crew evacuation aboard large ferries and passenger ships. Undoubtedly lifeboats are a less than perfect solution since they are heavy, difficult to launch and require high levels of maintenance and training. Over time, lifeboats have been, at least, partially replaced by inflatable life rafts.

Inflatable life rafts, as devices, are reasonably effective to the extent that there is a relatively large body of experience with regard to smaller life raft effectiveness that has developed with their use in small craft sinkings. While boarding a life raft from a sinking small craft is far from easy, experience shows that it can be accomplished by vessel crews in actual abandonment conditions.

On the other hand, large passenger vessels and large ferries use much larger rafts and often do not have a suitable boarding deck near the water level. Therefore, the sheer number of people that needs to be evacuated requires an alternate approach. Today, this approach includes the use of evacuation chutes and slides (MES).

Since evacuation slides have perceived disadvantages, it appears that the evacuation chute approach has now become more dominant.

Recently we were tasked to evaluate the safety of one of those evacuation chute systems and our investigation indicated that quite possibly there are issues with the effectiveness of those systems. Our review indicated that injuries during training are quite common.

This mirrors issues that have occurred with lifeboat deployment too, but there has been an effort to make lifeboat training and equipment safer. However, it appears that no such effort has occurred with marine evacuation chutes.

Oddly, besides training accidents, we also noted that the actual effectiveness of these chutes during an actual emergency, especially with passengers, is quite dubious due to a general lack of operational experience in actual emergency conditions. As near as we could determine, it is at least reasonable to question the effectiveness of these chute systems especially in any type of wave and wind conditions with regard to evacuation speeds, evacuation instructions, passenger size variables, chute blockages and evacuation injuries.

Quite possibly an open slide system is more effective. While there may be passengers who balk at using an open slide; that would be a personal responsibility issue (like seatbelts), rather than an issue where one balking or blocking passenger in a chute system can block the escape of the rest of the remaining passengers aboard the ship. A passenger stuck in a chute takes a long time to clear, especially in wave conditions, but a balking or stalled passenger on a slide can be shunted aside, nicely or not, which certainly would increase the effectiveness of slides over chutes in a real emergency.

Our investigation indicated that a reevaluation by IMO and national authorities of these chute systems based on operational experience during training exercises would be in order.  Such an investigation would look at training experience, but would particularly focus on manufacturer’s experience while attending training exercises, manufacturer’s evaluation of the effectiveness of the systems they sell and reevaluation of the original certification testing.

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