Alpine Butterfly Loop
Also known as: Butterfly Loop
loop knot
Life-safety notice
TyingPoint's illustrations are for learning. For any life-safety use — climbing, rope access, rescue, or load-bearing rigging — seek qualified in-person instruction, and always inspect and test every knot before you trust your weight (or anyone else's) to it.
Alpinists on glacier travel needed a knot that could do something most loops can't: sit in the middle of a rope, between two tied-in climbers, and hold a third climber's clip-in point securely no matter which direction the rope happened to pull from at the moment of a crevasse fall. A standard mid-line loop tends to distort or slip when loaded off-axis. The alpine butterfly was refined by mountaineers precisely because it stays put under load from the loop itself, from either standing end, or from any combination - a genuinely unusual property for a knot this simple to tie.
The tying method looks unlike most loop knots: instead of tucking a working end through a hole, it's built by folding a series of loose turns over each other and pulling one through the resulting gap. Lineworkers used a closely related knot for decades to make a temporary footloop on a hanging cable, which is where its "lineman's loop" nickname sometimes comes from, though the mountaineering and utility traditions arrived at the same shape somewhat independently.
Because it's tied entirely mid-rope with no access to an end, it's also the standard way to isolate a worn, kinked, or damaged section of a rope - the flawed section sits inside the loop and out of the load path, while the rest of the rope carries the strain as normal.
Search-and-rescue teams also favor it for a related reason: it's one of the easiest common loops to inspect and untie even after being loaded, unlike the figure-eight loop or double fisherman's knot, both of which can jam hard under a big fall. That combination - genuinely secure under multidirectional load, yet still reasonably easy to undo afterward - is unusual enough among knots that it's often taught right alongside the figure-eight as a core mountaineering skill rather than a niche specialty knot.
How to tie the Alpine Butterfly Loop
- 1Lay three turns of rope loosely across your palm.
- 2Pick up the turn nearest your fingertips and lift it clear of the other two.
- 3Carry that turn across and around both remaining turns, so it wraps them.
- 4Then tuck the same bight back underneath both turns and pull it out the far side - that bight becomes the loop.
- 5Pull both standing ends firmly apart to snug the knot into shape.
- 6Check the loop can be loaded from either standing end or from the loop itself without distorting.
Strength & security
Approx. strength retained: 70-75%
Its defining property is that it can be loaded in three different directions - either standing end, or the loop itself - without capsizing, which no other common mid-line loop reliably does. This makes it the standard choice for isolating a damaged section of rope or clipping a middle climber into a glacier rope team.
Cautions: It must be dressed carefully before loading; a loosely dressed alpine butterfly can slip under an off-axis pull. It is not designed to be tied at a rope's end - use a figure-eight loop or bowline there instead.
Alternatives
- Figure-Eight Loop
The better choice at a rope's actual end; the alpine butterfly is built specifically for a mid-line loop where both ends are already committed.
- Bowline on a Bight
Also usable mid-line, but doesn't share the alpine butterfly's true multi-directional loading tolerance.
FAQ
Can the alpine butterfly be tied at the end of a rope?
It can, but it isn't the right tool there - a figure-eight loop or bowline is the correct end-of-rope knot. The alpine butterfly's value is specifically its ability to sit mid-line.
Why do glacier rope teams use this particular knot?
Because a middle climber's clip-in point might be loaded from either direction along the rope during a crevasse fall, and the alpine butterfly is one of very few loops that holds securely regardless of load direction.
Is the alpine butterfly hard to untie after loading?
No - compared with a figure-eight loop or double fisherman's knot, it stays relatively easy to untie even after being weighted, which is part of why rescue teams favor it for a mid-rope loop.
Does the alpine butterfly work with modern low-stretch ropes?
Yes - its grip comes from the folded-turn geometry rather than friction against a slick rope surface, so it performs consistently across the static, low-stretch ropes common in canyoneering and rope-access work as well as the dynamic ropes used in traditional alpine climbing, which isn't true of every friction-dependent hitch.
Where does the name 'alpine butterfly' come from?
The finished loop's two symmetric wings, formed by the folded turns, resemble a butterfly's wings when laid flat, which is where the common name comes from; mountaineers sometimes also call it the lineman's loop after utility workers who use a nearly identical knot for cable footloops.
Gear that pairs with this knot
- Dynamic climbing rope (UIAA / EN 892 certified)
This loop is only as trustworthy as the rope it is tied in. A tie-in or anchor loop belongs in a fall-rated dynamic rope carrying a UIAA or EN 892 mark — never in utility rope from a hardware store, whose breaking strength is unrated.
- Locking carabiner (CE / UIAA rated)
Whatever clips into this loop has to be a certified climbing carabiner with a locking gate. An unrated snap clip has no published strength and is the wrong side of the line for any knot on this page.
- 7mm nylon cordelette cord
The butterfly is also the standard mid-cord loop for isolating a section of a cordelette when equalising an anchor, and cordelette has to be rated accessory cord.
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