The Aid Climbing Ratings System

How to Rate Aid Climbs

Eric Bjornstad aid climbing in the Valley of the Gods in Utah.
Legendary desert pioneer Eric Bjornstad aiding up a A1 crack in the Valley of the Gods in southern Utah in 1969. Photograph courtesy Eric Bjornstad

Aid climbing is simply climbing sections of cliffs by using equipment, including rope, aiders, cams, and carabiners, to ascend upward, whereas using only the rock for handholds and footholds to ascend and gear to protect yourself is free climbing. Aid climbing allows climbers to get to wild places on big walls and on faces that would otherwise be unclimbed. Aid climbing is an important part of every all-around climber’s skills.

The Aid Rating System

Aid routes are rated for difficulty by using a different system than that used for free climbing. The aid rating system uses A for aid climbing with the use of rock-damaging pitons or C for aid climbing without pitons as its basis, running from A0 to the almost mythical A6 rating. As in free climbing ratings that use the Yosemite Decimal System (YDS) in the United States, the aid rating for a route refers to the most difficult aid section. The A and C ratings are also subdivided with a + or – for routes, for example with aid placements that are not C3 but hard C2, which would be rated C2+.

Aid Ratings are Subjective

Remember that aid ratings, just like free climbing ratings, are subjective and always open to interpretation, depending on a climber’s experience. One man’s C3 pitch might be one woman’s C2+ pitch.

A0/C0: This rating is given to sections of mostly free routes that require minor sections of aid to progress upward. These aid section don’t require the use of aiders or other specialized aid gear but instead the climber ascends “French free” by simply grabbing gear and pulling up or stepping on pitons or bolts. Other AO/CO aid includes tension traverses, pendulums, and resting on gear. An example of an A0 route are the first three pitches of the West Face of El Capitan in Yosemite Valley, which can be done all-free at 5.11c or with three aid moves at 5.10 A0.

A1/C1: Easy aid climbing with solid bombproof gear placements that can hold any leader fall and the gear won’t pull out of the rock. Aiders and other aid equipment is required. Aid placements are usually bolts, fixed pitons, or straightforward placements of cams and nuts. Most aid pitches have C1/A1 sections. Examples of routes with C1 pitches are Moonlight Buttress, Prodigal Sun, and Touchstone Wall in Zion National Park.

A2/C2: Moderate aid climbing. Most of the placements are solid but could occasionally pull out if the leader falls on them. Nor do falls resulting from the gear pulling have injury potential. Sometimes aid pitches with strenuous, sideways, and awkward placements are given a C2 rating. A couple big walls with C2 aid pitches on them are Moonlight Buttress and Space Shot in Zion National Park, The Nose of El Capitan, and The Oracle tower in the Fisher Towers.

A3/C3: Hard aid climbing. Harder aid placements with consecutive marginal placements; increased fall potential (up to 20 feet); tricky and hard-to-find placements that only hold body weight; routefinding problems; and dangerous sections with hooks or old rivets. Most aid climbers will be challenged on C3 pitches. C3 placements always require testing. C3 routes also have greater fall potential than easier routes with the possibility of ripping out 8 or 10 pieces and falling 50 feet; falls, however, usually are not dangerous or have high injury potential. Many A3/C3 pitches require several hours to lead with complex gear placements. Examples of C3 aid routes are The Shield, Pacific Ocean Wall, and Wall of Early Morning Light on El Capitan.

A4/C4: Harder aid climbing with dangerous falls, marginal placements, and big scare factor. These pitches have sustained tricky placements, including many consecutive body-weight-only placements (up to 75 or so feet) and the possibility of bad falls onto ledges as well as long falls. Every placement needs to be bounce-tested so that the leader can string lots of bad placements together. Pitches can require at least a half-day to lead. Only extremely competent and experienced aid climbers lead C4 pitches. Most A4/C4 pitches require nailing with pitons or extended lengths of hooking. Examples of C4 aid routes are Lost in America and Wyoming Sheep Ranch on El Capitan.

A4+/C4+: Big danger factor—usually the hardest aid most climbers will do. Think A4 and then take it to the next level. Lots of time is required for these dangerous leads and the leader must move very carefully, testing every piece and sometimes standing on multiple pieces of gear to distribute body weight. The rock is often rotten and loose with expanding flakes and shifting blocks. Falls could be long zippers with uncertain landings on ledges with the possibility of multiple fractures or severe injury. An example is the Welcome to Wyoming pitch on Wyoming Sheep Ranch on El Capitan.

A5/C5: Extremely difficult aid climbing with no single piece of gear on a pitch able to catch and hold a leader fall. These pitches are not only extremely hard but also extremely scary and dangerous. Physical injury is the outcome of a fall. A5/C5 pitches have no drilled holes for hooking or enhanced placements; if they do, they are A4/C4. Belay anchors are solid. An example of an A5 route is The Reticent Wall on El Capitan, which requires eight days to climb its 21 pitches.

A6/C6: The mythical grade. Does it exist? Expect sustained A5/C5 aiding with bad belay anchors which won’t hold a fall. Think both climbers falling to the ground in case of failure.