Potentially dangerous interaction between Petzl RIG & Micro Traxion

It should be noted that this issue may also be possible with other similar equipment from a range of different brands.

It is important to state from the outset that the equipment used in the described incident below was not at fault and was in a good state of repair. Although it was ‘human error’, I don’t believe this type of event has been recorded before and the purpose of this report is to raise awareness of an unlikely, but possible, potentially dangerous interaction between 2 common devices used in the LCMLA Vertical Award scheme.

On the afternoon of the second day of a Vertical Leader training course in April 2022, we were covering the use of Traxion and pulley/jammer systems for hoisting. I had already demonstrated to the two candidates how to use and release the Traxion devices. They both competently demonstrated their ability to do so safely at ground level (but still with a full body weight on it) with both a Pro Traxion and Micro Traxion device. One candidate went up a 5m training pitch to a ledge with a Y hang and installed a Petzl Micro Traxion as part of a haul system. They then proceeded to haul another T/A about 1.5m up the wall. At this point of the exercise, they were to reverse the haul and lower the person on the rope. The candidate used a Petzl RIG (version 2 D021AA00) on the ‘dead’ side of the rope to lift the T/A enough to release the toothed cam on the Micro Traxion. This was successfully achieved but a moment later the T/A on the rope went into freefall, dropping around 1.5m onto the ground. This all occurred under direct supervision of the T/A and at no point had anything been done by the candidate that was not expected or safe.

The exact details of the few minutes after the fall are irrelevant here, but the T/A was thankfully uninjured, although a little bruised. The candidate was asked to leave the equipment exactly as used and make their way down safely.

The 2 devices were being used on Petzl Parallel 10.5mm rope (good condition) and using Petzl OK oval triple action or screw action locking karabiners. All equipment was compatible and being used as per manufacturers instructions and LCMLA scheme best practice.

When the situation was calm again and everyone was known to be okay, I ascended to the look at the setup. I had already formulated a hypothesis about how this had occurred. Seeing the equipment and speaking to the candidate and T/A had confirmed that both the Micro Traxion and Petzl RIG were being used correctly and the RIG handle was in the locked position when the fall occurred. Once I was able to see the exact position of the equipment, I was confident that I had identified the reason for the fall and was able to replicate it in situ (on camera) and again on the ground later.

Probable Cause

The candidate and T/A were similarly matched in terms of bodyweight, but perhaps the T/A was slightly heavier. As the candidate released the teeth of the Micro Traxion from the rope, they were raised up in their harness by the weight of the T/A below. The candidate’s hands were on the Micro Traxion and bracing against the wall. The rope in the RIG was not being held. The RIG had its handle in the locked position. As the participant was lifted, the top of the RIG came into contact with the base of the Micro Traxion. The Micro Traxion moved between the RIG side plates and it pressed the top of the RIG’s cam down, at the point where the ribs are, opening the cam and releasing the lock on the rope. Without a hand on the rope, and with pressure on the cam top, there was no locking or breaking action on the RIG. This resulted in the release and drop of the T/A.

The candidate would not have been expected to have a control hand on the rope at this point. The RIG was in the locked position and is a hands-free device in that mode.

I filmed the interaction in the exact location and have uploaded it to a private link on YouTube:

https://youtube.com/shorts/oEE4bQcBFbc

Comments

• This interaction was not a fault of the equipment, nor was it something that is isolated to these two items of equipment. I anticipate it would be possible to recreate the issue with a range of cammed belay devices and pulley/jammer setups.
• The participant was not at fault and operated the devices according to the manufacturers instructions and the training given.
• The supervising T/A (on the rope) was not at fault and was observing the operation throughout.
• A heavier casualty on a rope being counterbalanced by a lighter rescuer likely increased the chances of the 2 devices coming together.
• The position of the Traxion in relation to the RIG was unfortunately in the ‘sweet spot’ to cause this issue. It is something that might take many attempts to recreate, but clearly will, and has, always been possible.
• This incident would fall under the user-error category, but as it was something that had not been witnessed or reported before, I don’t believe it was reasonably foreseeable by anyone involved. That said, it is now a known issue and should be accounted for in training and safeguarding trainees.

Follow up actions

• This confirms to me the importance of a close-to-ground practice session in a controlled environment when first teaching these skills.
• I shall now specifically demonstrate this interaction as part of my teaching when using RIGs or similar devices.
• I shall introduce a requirement when training to either:
  • Maintain a hold of the dead rope during the counterbalance manoeuvre, even on a locked belay device, or,
  • Tie a backup knot a short way down the dead side of the rope to act a blocker in the event of uncontrolled release.
• I shall highlight the issue when I do Vertical Core Skills assessments if the candidate is unaware.

It should be noted that this issue may also be possible with other similar equipment from a range of different brands.