NDT Level II vs. Level III: What Each Can Do, and When You Need a Level III

Under ASNT's SNT-TC-1A and NAS 410, the certification standard used across aerospace, NDT personnel are certified at three main levels — I, II, and III — separately for each method. Level II and Level III are the two most often confused, because both are experienced inspectors who can work on their own. The difference is what each one is allowed to decide.

What a Level II Does

A Level II is qualified to:

• Set up and calibrate equipment
• Perform inspections and interpret and evaluate results against the applicable code, standard, or specification — including accept/reject decisions
• Prepare written instructions and report inspection results
• Provide on-the-job training and guidance to trainees and Level I personnel

In short, a Level II works to a procedure. Most day-to-day production inspection is Level II work.

What a Level III Does

A Level III is responsible for the NDT program behind the inspection. Under SNT-TC-1A, a Level III should be capable of:

• Developing, qualifying, and approving procedures
• Establishing and approving techniques
• Interpreting codes, standards, specifications, and procedures
• Designating the NDT methods, techniques, and procedures to be used
• Training and examining Level I and II personnel for certification

A Level III also needs a practical background in the materials, fabrication, and product technology involved, and general familiarity with other NDT methods — because they decide how parts get inspected, not just whether one passes.

Certification Is the Employer's Job

Under both SNT-TC-1A and NAS 410, certification is issued by the employer, based on the employer's written practice — the document that sets training hours, experience, exams, and vision requirements for each level and method. A training course or an outside agency can qualify someone, but it can't certify them. That's why a Level II certified at one company isn't automatically certified at the next.

The Responsible Level III Under NAS 410

NAS 410 requires the employer to designate a Responsible Level III for each method — the person accountable for the technical side of that method's NDT program. The role can be filled by an employee or contracted to an outside agency, as long as the employer documents the arrangement and the agency's suitability. Only the employer certifies personnel, even when the Responsible Level III is contracted.

When You Need a Level III

• Writing, revising, or approving NDT procedures and techniques
• Setting up or updating your written practice
• Training and examining Level I and II personnel for certification
• Answering questions a procedure doesn't cover — a code interpretation, a new part, or a new customer requirement
• Preparing for audits, including NADCAP for aerospace suppliers

Full-Time or On-Demand?

Many small and mid-sized shops don't have enough Level III work to justify a full-time hire. A contracted Level III can cover procedures, the written practice, examinations, and audit preparation, while your Level II staff handle production inspection.

Where Lion NDT fits in. We provide Level III consulting on demand — written practice (NDT manual) and procedure development, training and qualification exams, experience verification, code interpretation, internal and vendor audits, and accreditation readiness. Certification of your personnel stays with you, as the employer, under your written practice.