If you look close the next time you ride a lift, you will see a "catch" on the other side of the sheeve(wheel). It is there to catch the cable if there was ever to be a derail. It only let's the cable drop a few inches. And they have finger switches on each one to stop the lift if and when this happens. There is also a counter weight at the bottom of each lift, witch drops to counter act the slack in the line to keep the lift line from hitting the ground. I worked as a lift mechanic for 3 yrs at bear creek and was lucky enough to never see this happen, but there are so many fail safes to save the lift riders that you would never hit the ground or really come close. Unless the cable snaps. Every year they have to test each and every chair and lift line. For the grips(clamps on top of the chair) they run 3 test on each one. And for the chairs and lines they actually load the chairs with 55 gallon drums of water to act as people weight and they run multiable test on roll back and stopping power of each lift and line. But still no one can predict what mother nature brings as far as wind and weather. Hope this helps