| The following report and correspondence documents an actual
life safety
incident
involving the basic design flaw of the Petzl ascender, a climbing gear
failure wherein a Petzl model Ascension B17, unexpectedly disconnected
itself from the climbing rope while the climber was climbing on a cliff
side. The author personally witnessed this incident on Saturday 27
March 2004. Petzl was informed, and chose neither to follow through
with a
design review nor to notify the public how to avoid possible
danger due to its flawed product safety design. Petzl instructions for
use of
the ascender contain no information
about
this life threatening safety problem. As of this date, the Ascension
B17 ascender has
not
been recalled. The previous models of Petzl Ascension ascenders did not
have this dangerous design flaw. Tough decisions yet remain for Petzl,
for their
conscience,
and for their company's bottom line. When
the manufacturer does not make it clear to users what the safe limits
of use
are for the products they manufacture and sell, it falls to the users
to educate and inform ourselves, determine the life safety
limits of use, and to
gain
full knowledge of possible failure modes. Buyer beware, there are
serious product safety problems out there. Do you have one in your pack? |
 Many climbers, cavers, and rope rescue personnel are injured every year due to gear failure and product safety design flaws. Educate yourself and use good safety procedures. Never use climbing equipment that has been badly designed or is prone to failure. |
  |
 CLIMBER, ASCENDER, ROPE AT BASE OF PITCH Photo taken just minutes before the incident. |
 Petzl ascenders manufactured after approx 1999. |
Description of Petzl model B17 Ascension Ascender Failure
Mode The design of the nylon (plastic) cam "safety catch" in Petzl ascenders manufactured since 1999 has a curved crescent surface protruding for the thumb to manipulate it. The prior design did not have this. This design "feature" is described in Petzl promotional literature as a new improvement, which is "ergonomic". It is the protruding edge of this curved surface that unfortunately forms an arc wedge with the elongated smoothness and continuous angular position needed to induce lateral displacement of the safety catch when it is moved upward against a rough rock surface. That movement unlocks or disengages the safety while at the same time pulling the cam down and away from the rope capture enclosure. Once the rope is no longer captured, the ascender falls loosely off and away from the rope thereby disconnecting. |
Climbing Rope Using
Ascenders
- Gear Failure - Petzl Ascenders
TYPE OF INCIDENT: Gear Failure, non-injury.
REPORTED BY: Bonnie Crystal
INITIAL REPORT DATE: 18 APRIL 2004
DATE OF INCIDENT: Saturday 27 March 2004, approx 1530hrs.
INCIDENT LOCATION: Cliffside above the entrance to "R" Cave, California.
INCIDENT LOCATION WEATHER: Clear, sunny, temperature 17C degrees, no precipitation.
LOCATION DETAIL: Dry limestone cliff, with rough uneven face.
ROPE: PMI, 9mm Static in good condition.
SRT METHOD: American style, no rebelays.
RIGGING: Top anchor of rope to trees and rock outcroppings above cliff face. A rope pad with separate rigging is positioned between the rope and rock approximately 1meter from the top, where the rock is rough and the top of the pitch becomes more horizontal.
PITCH DISCRIPTION: 10meters approximate total pitch height. Excess rope is flaked into a bag at ground level at the takeoff position. Slight overhang at mid pitch, rope hangs free to the ground for the lower half of the pitch. Above mid-pitch, rope lays against rock with gradual curvature slope of about 10degrees to 30degrees. 2meters from the top, the rope lays in a wide angle V-notch in the rock (approx 130 degrees).
OBJECTIVE: Practice ascending the rope from the bottom to the top of the pitch.
WITNESSED BY: Bonnie Crystal
WITNESS/REPORTER EXPERIENCE LEVEL: 33years+ Comm towers; aid-climbing; vertical-caving
CLIMBER: "Mike" (surname withheld)
CLIMBER HANDEDNESS: Right handed, right footed.
CLIMBER EXPERIENCE LEVEL: Novice
CLIMBER SYSTEM TYPE: Frog ascending system.
CLIMBING SYSTEM UPPER ASCENDER DESCRIPTION: PETZL ACENSION B17-L LEFT HANDED ASCENDER, recent model, excellent condition, clean, functioning freely as designed, very little indication of wear marks or scratches, no visible indication of damage. Attached to a 5/16" webbing foot sling through a bottom hole. The other bottom hole is attached via a lanyard to the seat harness D screwlink.
CLIMBING SYSTEM LOWER ASCENDER DESCRIPTION: PETZL CROLL ASCENDER, recent model, excellent condition, functioning freely as designed, very little indication of wear marks or scratches, no visible indication of damage. Ascender attached direct to seat harness D screwlink. Figure-8 style GGG Frog chest harness attached to upper hole of ascender.
PHOTO OF
CLIMBER,
ASCENDER, AND ROPE AT BASE OF PITCH
This photo was taken just minutes
before the incident.
Dear Hank,
I originally sent an informal email report on an incident involving Petzl Ascension B17-L Ascender Unintentional Rope Disconnection to [xyz Petzl dealer] on 13 April 2004. I sent the informal email report to [xyz] because I own and use a lot of Petzl gear, which I have purchased from the good [xyz] company for many many years. He replied to me by email, indicating that he was forwarding my message to Petzl. On the following day, I posted an informal message on the San Francisco Bay Chapter of the National Speleological Society grotto's egroup describing the incident, because the incident happened at a cave during the SFBC grotto's regular vertical practice session. I was the only close eyewitness to the incident which involved a caver who was practicing vertical rope ascent on the cliff face above a cave entrance.
My informal message about the incident on the SFBC grotto egroup received a quick reply from another a Petzl dealer Mr.[abc]. He said that he had known about Unintentional Rope Disconnection with the updated B17 ascender since shortly after the new version of the ascender came out (1999). I asked Mr. [abc] a few questions in response to his comments. One of the questions I asked him was if he was speaking as a Petzl representative. At the time I am writing this, Mr. [abc] has not yet answered my questions.
I have not received a reply from Petzl to my initial informal report forwarded through [xyz]. I expected it would take some time for the report to be digested and a response or course of action to be formulated. In this email, I am providing Petzl, and other individuals directly involved with analysis of the incident with a more detailed report of the incident (attached below). Please be aware that correspondence regarding this may also be forwarded to concerned individuals, and thus may show up on the internet.
After the initial incident, back on the ground in a controlled environment, I re-created the failure mode of the ascender to try to understand it better. The failure mode is repeatable and requires only gentle motion for it to disconnect unintentionally from the rope. In other words: the ascender can come off the rope without the climber intentionally manipulating or disengaging the "safety catch", and in doing so, the ascender does not need to be torqued or pryed from the rope by force.
Upon close inspection, I observed that the design of the nylon cam "safety catch" has a curved crescent surface protruding for the thumb to manipulate it. This is described in Petzl promotional literature as a new improvement, which is "ergonomic". It is the protruding edge of this curved surface that forms an arc wedge with just the elongated smoothness and continuous angular position needed to induce lateral displacement of the safety catch when it is moved upward against a rough rock surface. That movement unlocks or disengages the safety while at the same time pulling the cam down and away from the rope capture enclosure. Once the rope is no longer captured, the ascender falls loosely off and away from the rope thereby disconnecting.
I have not encountered the above-described failure mode with such ease on the previous metal "safety catch" version of the Petzl Ascension Ascender, pre-1999. The previous version has a metal post safety catch manipulator protrusion instead of the nylon thumb crescent safety catch of the present-day version.
I look forward to Petzl's response to this report.
Best Regards,
Bonnie Crystal
18 APRIL 2004
Subject: RE: Petzl Ascender Unintentional Rope Disconnection
Date: 4/20/2004 4:46:13 AM GMT Standard Time
In a message dated 4/20/2004 4:46:13 AM GMT Standard Time, [Hank Moon at Petzl.com] writes:
Bonnie
Thank you for your very detailed description of the incident - much
appreciated. I have copied Steve on this post because of the following
statements he made in his post to the SFBC group:
"If any ascender opens under any circumstances, without the operator
deliberately opening the safety gate, this IS LIFE THREATENING."
"Other brands do not have such a problem."
Bonnie, you seem to share both of these opinions with Steve, so I
guess
this question is for you: would you briefly describe your view of how
Mike's life was endangered by the incident? Your report states that
after the ascender was re-attached to the rope, "Climber continues
climbing rope and reaches the top of the pitch without physical
injury."
This would seem to imply that there was an expectation of physical
injury, presumably from the lower ascender failing while the upper
was
briefly detached from the rope? If this is correct, would you also
give
your ideas of the possible mechanisms of such a failure? I am wondering
in all this if old fears about cast-aluminum jumars spontaneously
breaking are haunting this discusssion? Or am I reading too much into
the report?
I have no hard data on whether other brands might have "such a
problem"
- or not. I have heard stories of various non-Petzl ascenders
inadvertently coming off rope, but again, nothing I have personally
witnessed. I have, however, seen other types of failure. I was caving
in
TAG with my friend John about 15 years ago; can't remember the exact
cave, but it was multi-drop. John had just bought a pair of CMI
ascenders, having swallowed the misleading claim of "strongest on the
market". When I first saw them, I was impressed: their beefy frames
sure
*looked* stronger than my Petzls. Plus they were black (always cool).
Having bottomed the cave, we were headed out when John got a funny
look
on his face while getting on rope. "It broke," he said, holding up
one
of his brand-new CMI's. "What"?!!I moved closer to take a look. Somehow
during our descent, the safety catch on one of the CMI's had broken.
It
wasn't completely broken off, but it would no longer function as a
safety catch. So much for "strongest on the market", I thought. Being
a
mild paranoid type, John had 3 other ascenders with him, so the ascent
out of the cave was uneventful.
I will reply in more detail to your report later this week. In the
meantime if you can provide your perception of how the situation was
life-threatening, it would help me to prepare a more meaningful
response. I hope that you do not perceive this request as disingenuous
or evasive; if we were speaking in person, I am sure that you would
not.
However, the limitations of electronic communication can easily foster
misunderstandings. I hope that despite this difficulty, we can arrive
at
a clearer picture of the causes and importance of this incident.
Best regards
Hank
Subject: Re: Petzl Ascender Unintentional Rope Disconnection
20APR2004
Date: 4/20/2004 8:12:47 AM GMT Standard Time
TO: Mr. Hank Moon (Petzl America)
FROM: Ms. Bonnie Crystal
DATE: 20 APRIL 2004
Hi Hank,
Thank you very much for your courteous and friendly reply to my report.
Perhaps it is the responsibility of the manufacturer to make it clear to users what the safe limits of use are for the products manufactured and sold. Perhaps it is the responsibility of the users to be informed, determine the safe limits of use, and to gain full knowledge of possible failure modes. Perhaps it is good for independent organizations to determine safety guidelines or point out suggested limits of safe use for products. Or perhaps it is a combination of the above.
I'm not personally in a position to determine what the safe limits of use should be for Petzl products. As you have noticed, I have not admonished Petzl to go forth and tell the world about this problem or to recall or redesign the ascender. I leave those tough decisions to you, your conscience, and your company's bottom line. That's probably something you and your company will have to wrestle with in the days ahead. With the liability situation as it is in USA these days, I certainly don't envy your position, Hank!
As for your question of hanging on a cliffside by a rope with only one solitary ascender... I tend to go with the conventional wisdom that it isn't safe. The fact that the solitary ascender in this particular incident was a Petzl Croll may have made it somewhat more scary to me at that moment. In fact, thinking about it now, it seems a little scary even with a single prussik knot or a Rock Exotica or a Gibbs, but yes, the fact that it was just a Petzl Croll is a bit more scary than some other ascenders I can think of if I had the choice...
As to whether or not the incident was "life threatening"; that phrase was injected into the discussion by one of your Petzl dealers [Mr. abc]. But when asked about it, I responded that indeed, when the incident occurred, the climber and I both reacted with the feelings and physiological symptoms of a threat to the climber's life. Adrenaline flowed.
In my report to you, dated 18 APRIL 2004, you should note that I've made no value judgment on the incident. I have simply stated the facts as best I know them and remembered them from the incident. I suspect that Petzl will want to investigate the ascender failure mode further, and I suspect that a design review might be initiated. The failure mode is so easily recreated by anyone with the simple description of it, that I don't think there is a need for you to be supplied with diagrams or photos or a video of it being recreated. But if your staff has any problem recreating it, I can at some point make an mpeg video or other photos of it being recreated here.
At this point, I want to give you a couple of corrections and
clarifications
to the 18 APRIL 2004 report, a result of [B.F.'s] research today
([B.F.]
is the SFBC grotto vertical chair). B.F. was present at the site of the
incident, but was not in a position to directly view the incident in
action
easily. He has discovered a photo that he had taken as "Mike" was
attaching
his ascenders while starting to climb the rope. This photo was taken
just
minutes before the incident. Please note the photo image shows the gold
anodized color of the Petzl Ascension Ascender model B17-L, which is a
left-handed ascender. I have attached the photo to this email.
[...]
Best Regards,
Bonnie
Bonnie Crystal
20 APRIL 2004
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