Class 6: Hands, long fall, ropes, climb using equipment. Class-6 is serious rock climbing with ropes where you hang on your equipment and use it to pull yourself up the route. Class-6 climbing often is referred to as "aid climbing" because you use your equipment to "aid" in your ascent. There are not necessarily any handholds. You might fall on Class-6, and the fall could be long and result in sudden death unless your belayer saved your life with the rope. You wouldn't do it with your hands in your pockets, you would want a rope, and you might be so puckered up that you wouldn't even be thinking a happy song.

Class-6 is graded according to the technical difficulty of setting the equipment and the length of the potential falls (using "A" as an abbreviation for "Aid"):

• A1: easy aid climbing where placement would be easy and secure; no falls
• A2: moderate aid climbing where placement would be difficult but generally secure; short fall
• A3: hard aid climbing where placement would be difficult and insecure; moderate length falls
• A4: nearly impossible aid climbing with potentially long falls.