A SIF precursor is a high-risk situation in which a control is missing, has failed or is not followed, so that a serious injury or fatality is likely if the situation continues.
Precursors are conditions or practices, not events. In forklift operations, examples include a pedestrian crossing with no marking or barrier at a blind rack end, trucks routinely running with loads that block forward view, a disabled seat belt interlock, or dock work without a trailer restraint. Each can continue for months without an injury, which is why precursors are easy to miss in injury data.
Sites find precursors through job observations, near-miss and PSIF reviews, inspections, and data from detection or telematics systems that show where close approaches, speeding or impacts cluster. Once found, a precursor is addressed with a control from the higher tiers of the hierarchy of controls where possible, such as physical separation or automatic speed reduction on compatible forklifts, rather than with a reminder. A precursor is different from SIF exposure, which measures how often people are within reach of the hazard. See the forklift SIF prevention guide.