A PFAS is intended to protect a person from falling or to safely arrest a person if a fall occurs. This type of system is designed to be used when other types of fall protection are not practical or feasible in a specific work location. 

In a PFAS, a person wears a FBH with a connecting means, such as a lanyard or a self-retracting lifeline. Lanyards are composed of flexible rope, wire rope, or a webbing strap, which typically has a connector at each end for connecting to the body support and to a deceleration device, shock absorber, anchorage connector, or anchorage. They most commonly have a set length of no more than six feet and are designed with either internal or external shock absorbing functionality for use in fall arrest, work positioning, or restraint, or without a shock absorber for restraint applications only. A self-retracting lifeline retracts automatically into the unit housing as opposed to a lanyard, which hangs freely and with which falls are arrested by the engagement of an internal braking mechanism. This lanyard is attached to or includes a deceleration device that slows the person to a stop in the event of a fall.

A FBH and lanyard or a self-retracting lifeline are attached to an anchorage point to hold the person during and after a fall. The FBH and lanyard or self-retracting lifeline are worn, attached, and anchored by the person performing the work. A PFAS is meant to keep a person from hitting a lower floor level or other objects.

The body harness and lanyard are designed to exert less force on the body by dispersing the pressure placed on it during the fall and when the person comes to a stop or is arrested. 

The correct application of this type of fall protection system is critical. Therefore, following certain procedures, such as using, proper anchorage points, calculating potential fall distances and attaching the connection points properly helps ensure that the equipment performs as intended. Loose ends of straps can get caught in machinery or cause the accidental disengagement of an adjuster.

All FBHs must include a keeper or other components that are used to control the loose ends of straps.