Friday, October 10, 2008

Understanding Fall Factors

Many climbers don't really understand fall factors. But it's actually is quite straightforward. Fall factors may be determined by a simple formula:

Fall Factor = Length of Fall/Length of Rope

Using this formula, you can determine how hard you've hit the anchor. A factor 2 is the maximum that may be attained in a typical climbing fall, since the height of a fall can't exceed two times the length of the rope. Under normal circumstances, a factor 2 fall can only occur when a leader has no protection and he falls past the belayer. Once protection is placed, the distance of the fall as a function of the rope length is lessened, and the Fall Factor drops below 2.

A fall of 30 feet is significantly more serious if it takes place with 15 feet of rope out after the climber has placed no protection and falls past the belayer, than if it occurs 100 feet above the belayer (a fall factor of 1.15), in which case the dynamic stretch of the rope more effectively cushions the fall.

A factor 2 fall is very bad. Indeed, it is actually possible that an anchor may fail in the event of such a fall. As such, it is imperative that climbers place gear immediately after they start to climb as they leave a belay station. This will limit the possibility of a bad fall.

In the following video a climber is approximately twenty-five feet out from his belayer. He falls eight feet above his last piece of pro. With rope stretch and slippage he actually falls approximately twenty feet. That piece of pro eight feet below makes his rather large fall totally acceptable with a fall factor of 1.32.



If you are interested in finding out what kind of fall factors you've sustained or might have come close to sustaining, an online fall factor calculator may be found here.

After a breakdown of fall factors such as this, some people will still be confused. So the question must be asked, what are the main points that you should take away from this? They're actually quite simple:
  1. Always put in a piece immediately after you climb away from the anchor. This will protect your anchor from sustaining a factor 2 fall.
  2. This should be an obvious one. Always use a dynamic rope that is in good shape.

--Jason D. Martin

2 comments:

Craig Magtutu said...
This comment has been removed by the author.
Anonymous said...

Hi

Could you please explain how you calculated the fall factors of 1.15 and 1.32 in your article? When I work through the calculations, based on the numbers in your article, I get a different result - 0.3 for the first and 0.8 for the second.

I get 0.3 by dividing the fall of 30 feet by the 100 feet of rope out, and 0.8 by dividing the fall of 20 feet by the 25 feet of rope out. Am I missing something?

Many thanks.