What is a swing fall?

A swing fall happens when a worker falls while their anchor is off to one side rather than straight overhead. Once the line catches, they swing back under the anchor like a pendulum, through the low point and up the other side, and can strike columns, walls, equipment or the level below on the way.

How do you calculate the extra drop from a swing fall?

With a self-retracting lifeline, the line has already paid out to the worker’s position, so the extra drop is the line length less the anchor’s height above the D-ring: extra drop = √(offset² + height²) − height. With the anchor 3 m above the D-ring and the worker 2.4 m to one side, that is √(2.4² + 3²) − 3 = 0.84 m more than a fall straight below the anchor.

How far from an anchor can you work with an SRL?

Many SRL makers limit work to about 30° either side of the anchor, and the swing grows quickly beyond that. Alberta limits an SRL’s swing drop to 1.2 m. Work closer to the anchor, use a second anchor, or a horizontal lifeline that moves the anchor point with you.

How fast does a worker swing in a swing fall?

Fast enough to injure: the swing turns the height lost into speed through the low point. A worker anchored 3 m above the D-ring and 3 m to one side swings through the bottom at roughly 15 to 20 km/h, like running into a wall. The calculator works it out for your set-up.

Free tools

Swing fall calculator

Updated October 18, 20262 min tool

Drag the red anchor: left and right sets how far the worker is from it, up and down its height.

38° from vertical · too far from the anchor

At work

1

The set-up

Units

Jurisdiction

Anchor height

ft

Above the surface the worker stands on.

Worker's distance from the anchor

ft

Along the edge, from the point below the anchor.

Arrest distance

ft

From the label.

D-ring height

ft

Harness stretch and D-ring slide

ft

Safety margin

ft

Clearance available

ft

Working surface to the level below.

Something stands in the swing path (a column, a wall, equipment)

Anchor behind you, at your feet or set back from the edge? Use the fall clearance calculator.

2

Swing check

Clears the level below by 10.0 ft

The swing carries the worker 6.5 ft past the anchor before it swings back. Keep that path clear.

Extra drop from the swing

2.7ft

Alberta limit: 1.2 m (4 ft)

Clearance needed

9.7ft

Below the working surface.

Fastest point of the swing

12km/h

Through the low point, below the anchor.

Swing past the anchor

6.5ft

How far it carries to the other side.

The line starts 38° from vertical. Many makers limit work to about 30° either side of the anchor: work closer to it, or add an anchor.

From anchor	Angle	Extra drop	Clearance needed
0 ft	0°	0.0 ft	7.0 ft
2 ft	11°	0.2 ft	7.2 ft
4 ft	22°	0.8 ft	7.8 ft
6 ft	31°	1.6 ft	8.7 ft
8 ft	38°	2.8 ft	9.8 ft
10 ft	45°	4.1 ft	11.1 ft
12 ft	50°	5.6 ft	12.6 ft
15 ft	56°	8.0 ft	15.0 ft
20 ft	63°	12.3 ft	19.3 ft

The rules · Alberta

Fall protection from 3 m, from 1.2 m at a permanent work area, and lower where there is an unusual risk of injury (OHS Code s.139).
An SRL's swing drop at most 1.2 m (4 ft).
Arrest force at most 6 kN, or 8 kN with an E6 absorber (s.151).
A written fall protection plan, rescue included, where a worker could fall 3 m or more without guardrails (s.140).
Keep the whole swing path clear, on both sides of the anchor, down to the level below.

OHS Code Part 9

A summary to plan with. The regulation and your employer's procedures govern.

A worker anchored off to one side doesn't fall straight down: once the line catches, they swing back under the anchor. This calculator plays that swing and works out the extra drop it adds, how fast the worker moves through the low point, how far past the anchor they travel, and whether they hit anything on the way.

The extra drop

A self-retracting lifeline keeps its line tight, so by the time a worker off to one side falls, the line has already paid out to where they stood. When they swing back under the anchor, all of that line hangs straight down:

Extra drop = √(offset² + height²) − height, where height is the anchor's height above the D-ring.

A lanyard limits the drop to its own length, but the offset still swings the worker sideways, and that is where most swing-fall injuries come from: hitting a column, a wall or a piece of equipment at speed.

Keep the swing path clear on both sides

The worker swings past the anchor as far as they started from it, less what the swing loses. Everything in that arc, down to the level below, is something they can hit.

Reducing the swing

Work as close to directly below the anchor as you can, and move the anchor as the work moves.
Use a horizontal lifeline or a trolley on a beam so the anchor point travels with the worker.
Raise the anchor: the same offset makes a smaller angle, and a smaller extra drop, from higher up.
Add anchors rather than stretching the reach of one.

For anchors behind you, at your feet or set back from an edge, use the fall clearance calculator, and our training covers swing falls and rescue.

Sources: Alberta OHS Code s.145 (SRL swing drop of 1.2 m); ANSI/ASSP Z359.14-2021 and CSA Z259.2.2-17 for SRLs; fall protection makers' swing-fall guidance (Guardian, 3M). The swing is simulated as a damped pendulum; real swings lose more to the harness and the body, so treat the speeds as an upper estimate.

Frequently asked questions

What is a swing fall?: A swing fall happens when a worker falls while their anchor is off to one side rather than straight overhead. Once the line catches, they swing back under the anchor like a pendulum, through the low point and up the other side, and can strike columns, walls, equipment or the level below on the way.
How do you calculate the extra drop from a swing fall?: With a self-retracting lifeline, the line has already paid out to the worker’s position, so the extra drop is the line length less the anchor’s height above the D-ring: extra drop = √(offset² + height²) − height. With the anchor 3 m above the D-ring and the worker 2.4 m to one side, that is √(2.4² + 3²) − 3 = 0.84 m more than a fall straight below the anchor.
How far from an anchor can you work with an SRL?: Many SRL makers limit work to about 30° either side of the anchor, and the swing grows quickly beyond that. Alberta limits an SRL’s swing drop to 1.2 m. Work closer to the anchor, use a second anchor, or a horizontal lifeline that moves the anchor point with you.
How fast does a worker swing in a swing fall?: Fast enough to injure: the swing turns the height lost into speed through the low point. A worker anchored 3 m above the D-ring and 3 m to one side swings through the bottom at roughly 15 to 20 km/h, like running into a wall. The calculator works it out for your set-up.

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