A standard lift plan is a pre-lift checklist that covers routine crane operations — load weight, crane configuration, rigging selection, and basic safety precautions. Most competent riggers can prepare one on site before a straightforward pick.
A critical lift plan is a significantly more detailed engineering document required when the lift exceeds 75% of the crane’s rated capacity (per OSHA 1926.751 and widely adopted industry standards), involves multiple cranes, or poses elevated risk. The critical lift plan adds formal engineering calculations, a detailed rigging sketch approved by a Qualified Person (PE stamp required for custom-engineered lifting devices) with sling angles and hardware specifications, a site plan showing crane position and swing path, ground bearing analysis, a dedicated communication protocol, and a multi-signature sign-off sheet (per USACE EM 385-1-1 and industry best practice).
The key distinction: a lift plan is operational. A critical lift plan is engineered. The additional rigor exists because the margin for error shrinks as loads approach crane capacity limits.