A serious injury or fatality (SIF) is a work-related injury that is fatal, life-threatening or life-altering, such as an amputation, a crush injury needing hospital admission, or a permanent disability.
SIF is an industry term, not a legal category, and companies draw its boundary slightly differently. The closest regulatory anchor in the US is OSHA’s severe injury reporting rule, 29 CFR 1904.39, which requires employers to report a work-related fatality within 8 hours and an in-patient hospitalization, amputation or loss of an eye within 24 hours.
Forklift SIFs usually involve high energy: a pedestrian struck or crushed by a truck, an operator caught under an overturning truck, or a falling load. SIF prevention is treated as its own discipline because the causes of serious injuries often differ from the causes of minor ones, so a falling total recordable rate does not show that SIF risk is falling. SIF programs therefore focus on precursors and on exposure to high-energy hazards rather than on injury counts. The forklift SIF prevention guide sets out the controls.