main and backup failed webbing tested but whats the backstory?

UPDATE: A friend told me that one of the guys fell up a tree and was also able to prevent something from happening to the other one.

The International Slackline Association has compiled a multitude of tests over the years here:

https://data.slacklineinternational.org/safety/research/

Without a question, permarigged highlines/webbings degrade, often show a 50% reduction in strength over relatively short periods of time. Some data shows sheathed webbings degrade slower, and, ultimately, webbing materials (nylon, polyester, UHMWPE, aramids) and construction degrade at different rates.

The webbing in this case, as I understand, was an unsheathed UHMWPE that was permarigged for 6 months or more. UHMWPE webbing is low-stretch and, across all simulated and real-world testing, experiences higher peak forces during falls. Additionally, UV-degraded webbings tested demonstrate a lower modulus of elasticity (lower stretch).

Furthermore, fall height increases the impact force, and therefore peak load, on the webbing. It has long been theorized that loose backups may experience higher peak loading (Jerry Miszewski et al), but it's unknown at this point whether or how much this may have factored into this specific incident.

Put these known issues together and you have a recipe with all the ingredients for disaster.

We are incredibly fortunate that our friends survived. The ISA was founded (exclusively by active slackliners) in large part to study and disseminate slackline safety. Sadly, several vocal members of the slackline community, including some of the most well-known slackliners, railed strongly against its formation and continued their opposition as they saw the ISA as trying to "govern" or "control" how people slackline. Despite no evidence of this stance and significant outreach and discussion by slackliners involved in (and outside of) the ISA, a vocal minority sowed distrust in the organization and hampered their ability to share this vital and life-saving information.

The information that could have prevented this incident and near-tragedy has been published and available for years. It's not as flashy or fun as the YouTube content you get from Ryan Jenks (HowNot2) or others, but is necessary and critical for our community. As a slackline/highline/whateverline rigger with people's lives in your hands, please consider the data generated and/or shared by the ISA as an important part of your rigging knowledge toolkit.

290m line at CRG was rigged and two people went to do a tandem session on it. One guy whipped and the mainline failed. They then fell on the backup which also failed. Both guys were at death fall height but got extremely lucky and walked away with some scrapes and no lasting injuries.

The main/backup section that failed was permarigged for 9 months before it was used in that rig while the non-permarigged pieces broke near MBS. For more detail join the Slackchat Facebook group since that's where it was posted.