Fall Arrest Systems and Fall Factor

When hazard mitigation and travel restraint are not feasible—such as in vertical rescue scenarios or rope access on exposed structures—fall arrest systems become the last line of defense. These systems must not only stop a fall in progress but do so without causing serious injury to the worker or rescuer.

This segment breaks down what makes a fall arrest system effective and why understanding fall factor is essential in system design and decision-making.

What Is a Fall Arrest System?

A fall arrest system is designed to stop a fall after it begins. Unlike travel restraint, it accepts that exposure to a drop is present and prepares to manage the kinetic energy of a falling body.

Key Components:

• Full-body harness

• Energy-absorbing lanyard or Self-Retracting Lifeline (SRL)

• Certified anchor point (meeting OSHA and ANSI Z359 standards)

• Connectors (carabiners, lanyard hooks, rope grabs)

In rope rescue environments, fall arrest systems also include:

• Rope-based belay systems

• Backup devices on mainlines

• Personal edge protection protocols

Understanding Fall Factor

Fall factor is a measure of the severity of a fall. It determines how much energy the system will need to absorb and is calculated using:

Fall Factor = Distance Fallen ÷ Length of Rope In Use

Example Scenarios:

• Fall Factor 1: A person falls 6 feet while attached to 6 feet of rope or lanyard

• Fall Factor 2: A person falls 12 feet with only 6 feet of rope between them and the anchor point

The higher the fall factor, the more force is applied to the system, and the greater the risk of equipment failure or injury.

In real-world terms, a Fall Factor 2 is potentially deadly—especially if the system lacks dynamic energy absorption or uses non-rated anchors.

Arrest Forces and System Behavior

• Arrest forces can easily exceed 6kN (1350 lbs) in high-factor falls

• Shock absorbers reduce force transferred to the harness and anchor

• Ropes or webbing that are too static can transmit unsafe forces directly to the user

• Anchor orientation affects both fall distance and force direction

System Planning for Arrest

When deploying a fall arrest system, always evaluate:

• Total fall distance including lanyard length, shock pack deployment, and body elongation

• Clearance distance below the worker to avoid ground impact

• Harness connection point (back D-ring vs. front D-ring) and its effect on swing potential

Misconceptions and Common Errors

• Clipping into an anchor at foot level maximizes fall factor risk

• Using fall arrest gear in restraint applications can give a false sense of safety

• Relying on non-rated or improvised anchor points introduces critical failure points

• Failing to inspect and calculate clearance requirements can result in contact with lower surfaces even after arrest

A fall arrest system is a reactive safety measure—but it has to be engineered proactively. Understanding fall factor, energy transfer, and anchor dynamics is crucial to building a reliable safety net when mitigation is no longer possible.

Up next, we will explore lead climbing and protected climbing with a bypass lanyard—two very different approaches to vertical movement with very different risk profiles.

Peace on your Days

Lance