If you suspect a belay device may fail, what safety measure should you use?

• A. Engage a backup knot as redundancy.
• B. Tighten the rope until it stops moving.
• C. Unclip the climber from the rope.
• D. Stop all operations and watch.

Answer: (A)

When a belay device might fail, you want a second, independent way to stop a fall. Engaging a backup knot provides redundancy, giving you a second line of protection that doesn’t rely on the belay device functioning perfectly. If the device hesitates or slips, the knot can still arrest the climber’s descent, keeping them safe while you address the issue. The other actions don’t add that safety layer: tightening the rope doesn’t create a fail-safe, unclipping the climber releases control, and stopping all activity while watching leaves the climber unprotected.