knot that can be used to form a loop in the standing part of a line.
butterfly knot (Wikipedia)
The butterfly loop, also known as lineman's loop, butterfly knot, alpine butterfly knot, Swiss loop and lineman's rider, is a knot used to form a fixed loop in the middle of a rope. Tied in the bight, it can be made in a rope without access to either of the ends; this is a distinct advantage when working with long climbing ropes. The butterfly loop is an excellent mid-line rigging knot; it handles multi-directional loading well and has a symmetrical shape that makes it easy to inspect. In a climbing context it is also useful for traverse lines, some anchors, shortening rope slings, and for isolating damaged sections of rope.
| Butterfly loop | |
|---|---|
 A butterfly loop with a carabiner. | |
| Names | Butterfly loop, alpine butterfly knot, butterfly knot, lineman's loop, Swiss loop, lineman's rider |
| Category | Loop |
| Related | Alpine butterfly bend, farmer's loop, artillery loop, span loop |
| Releasing | Non-jamming |
| Typical use | Fixed loop on the bight. Isolating a worn section of rope. |
| ABoK | #331, #532, #1053 |
| Instructions | [1] |