Since the 2018 revision of the crane operator rule, the question has had a clear two-part answer, and the second part is the one employers miss.
Certification or licensing. Where a state or local government issues operator licenses that meet the rule's criteria, the operator must hold that license, which is valid for no longer than five years (29 CFR 1926.1427(c)(1)). Otherwise the operator must be certified by an accredited crane operator testing organization or through an audited employer program (29 CFR 1926.1427(c)(2), 1926.1427(d), 1926.1427(e)). Whichever route, the employer pays: certification or licensure must be provided at no cost to the employee (29 CFR 1926.1427(c)(3)).
Training before certification. An employee who is not yet certified and evaluated may operate only as an operator-in-training under supervision (29 CFR 1926.1427(a)(1)), with the training requirements in paragraph (b). Retraining is required when performance or an evaluation shows it is needed (29 CFR 1926.1427(b)(5)).
The employer's evaluation. Through an evaluation, the employer must ensure each operator has demonstrated the skills, knowledge and ability to recognize and avert risk needed to operate the equipment safely — including the specific safety devices, operational aids, software, size and configuration — and the ability to perform the hoisting the assigned work requires, including blind lifts, personnel hoisting and multi-crane lifts where applicable (29 CFR 1926.1427(f)(1)). The rule says plainly that possessing a certificate or degree cannot, by itself, make a person qualified for this purpose (29 CFR 1926.1427(f)(3)). The evaluator must have the knowledge, training and experience to assess operators (1926.1427(f)(4)) and must be an employee or agent of the employer (1926.1427(f)(5)). The evaluation is documented with the operator's name, the evaluator's name and signature, the date, and the make, model and configuration of the equipment, and the document is kept available at the worksite (29 CFR 1926.1427(f)(6)). Retraining triggers a re-evaluation on that subject (1926.1427(f)(7)).
Who is exempt. Operators of derricks, sideboom cranes, and equipment with a maximum rated capacity of 2,000 pounds or less are outside 1926.1427, though their own sections carry training requirements (29 CFR 1926.1427(a)(2)).
The card proves the operator passed a test. The evaluation proves they can run the crane you actually have, on the lifts you actually do. An inspector will ask for the second document, and it has to name the machine.