Free fall is one of the most critical phases of a fall from height because it is the period during which a worker accelerates under gravity before any protective equipment starts limiting the fall. During this stage, the body gains speed rapidly, increasing the amount of kinetic energy that must later be absorbed by the fall arrest system. The longer the free fall, the greater the forces acting on the worker, the harness, the connectors, the energy absorber and the anchor point once the system becomes loaded.
Reducing free fall is one of the primary objectives of every work at height safety programme. Modern fall protection equipment is specifically designed to minimise both free fall distance and the arrest forces that follow, but the safest solution is always to prevent unnecessary free fall through careful planning, correct anchor placement and appropriate equipment selection. Understanding how free fall develops is therefore essential for anyone responsible for designing, supervising or carrying out work at height.
What Happens During Free Fall
Free fall begins at the moment a worker loses support and continues until the connecting system becomes fully tensioned. During this short period, the worker is influenced only by gravity and accelerates downward at approximately 9.81 m/s². Although the duration of free fall is often measured in fractions of a second, the increase in speed is significant enough to have a major influence on the forces generated during fall arrest.
As velocity increases, the worker’s kinetic energy increases as well. Because kinetic energy rises with the square of velocity, relatively small increases in free fall distance can produce substantially greater arrest forces when the system eventually stops the fall. This is why a difference of only one or two metres in free fall distance can dramatically change the demands placed on both the equipment and the supporting structure.
The free fall phase ends when the lanyard, self retracting lifeline or other connecting device becomes fully loaded. From that point onwards, the energy absorber or braking mechanism begins reducing the worker’s speed until the fall is completely arrested.
Although modern fall protection systems are designed to manage these forces safely, they cannot eliminate the physical effects of excessive free fall. Good planning therefore focuses on preventing unnecessary acceleration rather than relying entirely on equipment performance.
Factors That Affect Free Fall Distance
Free fall distance depends primarily on how the fall protection system has been configured before the incident occurs. The same worker using the same equipment can experience very different free fall distances simply by changing the position of the anchor point.
Anchor location is the single most important factor. When the anchor is positioned directly above the worker, the connecting system remains relatively short and becomes tensioned almost immediately if a fall occurs. This minimises free fall and significantly reduces the energy that must later be absorbed.
If the anchor is positioned at harness level, the worker falls further before the lanyard becomes fully loaded. The longest free falls generally occur when the anchor is located at foot level because the worker may fall almost twice the length of the lanyard before arrest begins. This configuration produces the highest fall factor and the greatest dynamic loading throughout the system.
Other factors that influence free fall include:
- Length of the connecting lanyard.
- Amount of slack within the system.
- Position of the worker relative to the anchor.
- Type of connecting device being used.
- Movement of the worker during the task.
- Structural deflection of the anchor system under load.
Because these variables interact, free fall should always be assessed during the planning stage rather than estimated after equipment has already been selected.
How Free Fall Influences Fall Arrest Performance
Free fall has a direct effect on every stage of the fall arrest process. As free fall distance increases, the worker reaches a higher velocity before the arrest system begins operating. This generates greater dynamic loads that must be controlled by the energy absorber, harness and anchor system.
Energy absorbing lanyards certified to EN 355 are specifically designed to reduce these loads by extending during deployment. During certification testing, they must limit the maximum arrest force transmitted to the user to 6 kN. However, longer free falls generally require greater absorber deployment, increasing both the total stopping distance and the clearance required beneath the worker.
Self retracting lifelines certified to EN 360 minimise free fall by maintaining continuous tension in the lifeline. Their braking mechanisms activate almost immediately after rapid acceleration is detected, significantly reducing both free fall distance and total arrest distance compared with fixed length lanyards.
Longer free fall also increases the required fall clearance. Additional space is needed not only for energy absorber deployment but also for harness stretch, connector movement, body position and the required safety margin. If sufficient clearance is unavailable, the worker may strike the ground or another obstacle before the system completes the arrest process.
For these reasons, reducing free fall improves almost every aspect of fall protection performance, including lower arrest forces, shorter stopping distances and reduced demands on the anchor system.
Equipment and System Design to Reduce Free Fall
The most effective way to reduce free fall is through careful system design. Equipment should be selected not only for compliance with safety standards but also for its ability to minimise unnecessary movement during a fall.
Overhead anchor points remain the preferred solution wherever reasonably practicable. By positioning the anchor above the worker, free fall is kept to a minimum and arrest forces are significantly reduced. This arrangement also decreases fall factor and often reduces the amount of clearance required beneath the worker.
Self retracting lifelines provide another effective solution because they automatically retract unused lifeline during normal movement. Unlike traditional lanyards, which may contain significant slack, self retracting devices maintain continuous tension and engage rapidly if a fall occurs.
Work restraint systems eliminate free fall altogether under normal operating conditions. Instead of stopping a fall after it begins, they prevent the worker from reaching the hazardous edge in the first place. Where the task allows, restraint systems are generally preferred over fall arrest because they remove the possibility of free fall entirely.
Equipment commonly used to minimise free fall includes:
- Overhead anchor systems.
- Self retracting lifelines certified to EN 360.
- Work restraint systems.
- Rigid rail fall arrest systems.
- Guided type fall arresters on vertical lifelines.
- Adjustable lanyards that reduce unnecessary slack.
Selecting the correct equipment should always form part of the workplace risk assessment and should consider the specific working environment rather than relying on generic solutions.
Common Mistakes and Best Practice
Many work at height incidents result from poor planning rather than equipment failure. One of the most common mistakes is using a standard energy absorbing lanyard with a foot level anchor without considering the resulting free fall distance. Although some equipment is specifically approved for leading edge or low anchor applications, these situations require careful assessment because they generate substantially greater forces than overhead configurations.
Another frequent error is allowing unnecessary slack within the system. Extension connectors, excessively long lanyards or poor anchor placement all increase free fall distance without providing any additional protection. Good practice is to keep the connecting system as short as practical while allowing the worker sufficient freedom to complete the task safely.
Workers also sometimes assume that certified equipment alone guarantees safety regardless of how it is used. In reality, the performance values established during laboratory testing depend on correct installation, suitable anchor locations and compliance with the manufacturer’s instructions. Changing equipment configuration may alter free fall distance, fall factor and arrest forces beyond those anticipated during certification.
Best practice begins with eliminating the need for fall arrest wherever possible through collective protection or work restraint. Where fall arrest remains necessary, anchors should be positioned above the worker whenever practical, equipment should be compatible and correctly adjusted, and sufficient fall clearance should always be available. Regular inspection, practical training and a documented rescue plan complete the system by ensuring that equipment continues to perform effectively throughout its service life.
Free fall is the stage of a fall that determines how much energy must ultimately be controlled by the fall protection system. By understanding the factors that influence free fall distance and designing work to minimise it, employers can significantly reduce arrest forces, improve equipment performance and provide a safer working environment for everyone operating at height.