Wrongs and right about quickdraws

INTERVIEWS

Wednesday, 24 July



This is the quickdraw that the police showed to Tito's father.

Picture published first by Grimper Magazine showing the wrong assembled quickdraw, the rubber string and the right assembled rubber string, but notice that the rubber string is placed at the wrong biner.

2. Wrong assembled dog bone fixation.
A short rubber capsule makes the error easier to spot. The weight of the biner should be enough to pull it out of position.

4. Inside rubber like used by Black Diamond and Mammut can also be wrongly attached, but the mistake is hard to do and easy to spot.

Picture  from the new Petzl safety manual for use of rubber strings.



In the aftermaths of the tragic accident of Tito Traversa, it has been a broad discussion on 8a.nu and other climbing forums about the whys and how of the quickdraw’s failure. In many cases, it seems to be some misunderstandings on the purpose of the rubber string attached to the sling. After have seen the picture that explains how the rubber string was wrong assembled with an example of a right assembled quickdraw, we decided at 8a.nu to find some answers. Because this picture just shows how difficult this issue is, even though the rubber string is correctly mounted, it’s placed at the wrong end of the sling on the “right” assembled quickdraw, fixating the straight gate biner.

We contacted therefore Andres Lietha, who works as Head of Business Unit Hardware at Mammut in Switzerland. All the product managers and developers for safety gear work in his department (ropes, biners, slings, harnesses, etc.) meaning that he’s pretty much involved in all safety gear development and issues. We want already here to emphasize that no Mammut gear was involved in the accident. We are directing our questions to Mr Andres Lietha because he’s an expert in this field.

During the design, how do the engineers take into account the factor of human mistakes and how much does it influence the outcome of the product?
If you look at the accidents statistics you will very rarely or almost never find accidents due to pure gear failures – all the gear on the market has to fulfill the EN Norms, which provide quite a safe margin to the impact forces, which can happen. Accidents are almost always based on human failure or a combination of human failure with aging problems or other factors. And what’s very important: EN Norms do not cover human failures / misuse.

So to avoid this human failures is definitely at focus in each design / development process. But there is also always a question about how far you want to go. For example: There have been some accidents when people tied in to the gear loops of the harness – so should we make all gear loops of all harnesses strong enough to compensate this failure? We decided to do this on rental harnesses, as we expect this failure to happen more frequently with rental clients, but did not apply it on all other harnesses as this makes the gear loops big and stiff and the harness a bit uncomfortably and more expensive.

Is there any established method for predicting the different situations a product may encounter (regarding human behaviour and thereby the risk of not understanding the proper use of the gear in question)?
We try to go systematically through all variants of use and misuse on a product but there is no established method to make sure this checklist is complete.

How does designers of safety gear get feedback from users?  
We have a defined internal validation process for new safety gear. The user is of course not involved – we cannot test safety with users. If we start to sell new safety gear we have to be 100% sure it works. Of course we still collect user feedbacks about design, handling or not safety related features in a later stage. 

The use of rubber strings on quickdraws is not a new feature, what are the mayor advantages of that piece of gear?
There are two purposes: 
– Avoid 180 degree turning of the biner, that makes the clipping of the rope very uncomfortable .
– Avoid 90 degree turning of the biner that can lead to critical across loading.
So it’s definitely an essential little piece - if you don’t fix your rope biner you create other risks. Have also in mind, that a fixation of the upper bolt biner is wrong, and can also create a critical biner position on the bolt and across loading.

Have you followed the discussions on the web forums about the causes of this specific accident?
When I have a look at the comments on 8a.nu there seems to be a lot of misunderstanding and mixing up of the possible failures – may be it would be worth to put them together again and explain what is safe or not.

1. Open sling failure - This can happen with any type of fixation rubber and can also happen while climbing after a correct assembling. This problem was well known since a couple of year – but it’ seems that many climbers are still not aware of this. Solution: Never use any biner fixation on an open sling - this is not a new fact!

2. Wrong assembled Dog Bone Fixation - This can only happen with long Dog Bones or / and thin, flexible slings (see picture with the redish webbing) With short dog bones and a thick sling (eg. 16mm) the failure is not possible, as after a wrong assembling, the sling falls directly apart (see picture with the yellowish webbing).
The wrong assembled dog bone type was principally known – but we were probably less aware about the potential risk.

3. The failure with the fixation type as shown here - It seems that this type of fixation should not be used any more to avoid this potential failure. We at Mammut never sold this type of rubber piece so we have never discussed it.

4. It is also possible to assemble inside rubber wrong – but this seems to be well visible (see picture with the grey sling).
However in Titos case, the wrong rubber string placement was pretty well visible too.

In the light of what just happened, do you think it would be better to skip the rubber strings all together, or is there any other ways to make the use of the strings more safe?
Definitely not, this would create new, probably higher risks – use a short dog bone for thicker, or with thin slings an inside rubber type to avoid this problem. Never use any a fixation on open slings. And probably generally: don’t use gear from other persons. However, my perception about when failure is possible or not, changed quite a bit after this case.

There is also an excellent document from our friends from Petzl available



1  C O M M E N T S:
Sort by: Date A Reply A