2.2 CP-189, CP-105, NAS 410 & ISO 9712

Standards and Central Schemes: CP-189, CP-105, NAS 410, ISO 9712

Where SNT-TC-1A is a flexible guideline, the documents in this section are firmer, more specialized, or philosophically different. A Level III is expected to slot each one into the right role and to know the single feature that most often appears on the exam.

ANSI/ASNT CP-189 — a national standard, not a guideline

ANSI/ASNT CP-189, Standard for Qualification and Certification of Nondestructive Testing Personnel, looks structurally like SNT-TC-1A but is a fundamentally different document. It is an American National Standard, developed through the American National Standards Institute (ANSI) consensus process and ANSI-accredited. It uses shall language, so its provisions are requirements, not recommendations. The scheme is still employer-based — the employer certifies — but once CP-189 is invoked (typically by a contract or a referencing code), its minimums are mandatory, and the employer's written practice must meet or exceed them rather than relax them.

A frequently tested distinction: CP-189 requires the employer's NDT Level III to hold an ASNT NDT Level III certificate (or an ACCP Professional Level III certificate) in the applicable method — an outside, verifiable credential. SNT-TC-1A, by contrast, permits an employer to qualify its own Level III by examination without an ASNT certificate. That makes CP-189 the 'harder' document: mandatory language, a third-party-verified Level III, and defined outside-agency rules.

ANSI/ASNT CP-105 — the body of knowledge

ANSI/ASNT CP-105, Standard Topical Outlines for Qualification of Nondestructive Testing Personnel, plays a different role entirely. It defines the body of knowledge — the topical outlines — for each method and level. It answers 'what must a PT Level II course and examination cover?' rather than 'how many hours, and who certifies?' Both SNT-TC-1A and CP-189 point to CP-105 for the content of training courses and examinations. ASNT NDT Level III examinations, including the Basic exam you are preparing for, are built from CP-105 outlines; every tested topic traces back to a CP-105 line item.

NAS 410 — aerospace personnel

NAS 410, NAS Certification and Qualification of Nondestructive Test Personnel, is published by the Aerospace Industries Association (AIA). It is the United States aerospace standard for NDT personnel and is employer-based like SNT-TC-1A and CP-189, but it is written for the tighter controls of aircraft manufacturing and maintenance. Its European counterpart, EN 4179, is technically harmonized with NAS 410. NAS 410 defines a Responsible Level 3 (RL3) and imposes stricter training, experience, and outside-agency provisions than general-industry SNT-TC-1A. When a part is aerospace, expect NAS 410 or EN 4179 rather than SNT-TC-1A.

ISO 9712 — central (third-party) certification

ISO 9712, Non-destructive testing — Qualification and certification of NDT personnel, is the dominant international scheme and embodies the opposite philosophy from the employer-based documents. Under ISO 9712 an independent certification body, not the employer, certifies the individual. Candidates train, accumulate documented experience, and pass general, specific, and practical examinations administered through an authorized qualification body; the certification body then issues a credential that the individual carries between employers — it is portable. Before the person works at a given site, the employer still issues an authorization to operate under its own procedures, but the underlying certification is third-party. ASNT operates an ISO 9712-based program under ANSI/ASNT CP-106, and its older central program is the ASNT Central Certification Program (ACCP).

Employer-based versus central — the core comparison

The decisive mental model is who holds the authority. In employer-based schemes (SNT-TC-1A, CP-189, NAS 410) the employer certifies, the credential is tied to the job, and the written practice is the control document. In central schemes (ISO 9712, CP-106, ACCP) an independent body certifies, the credential is portable, and the employer adds only an authorization to work under its procedures. Match the scenario's certifying party to the right document and most exam items resolve immediately.

Outside agencies and why the choice matters

Both CP-189 and NAS 410 formally recognize an outside agency — a contractor that provides NDT services or examines personnel on the employer's behalf — and impose controls so that outsourcing does not dilute accountability. Even when an outside Level III writes and administers examinations, the employer still certifies its own people under an employer-based scheme. The practical takeaway is that scheme selection is driven by the customer and the sector: general industry commonly invokes SNT-TC-1A or CP-189, aerospace invokes NAS 410 or EN 4179, and international or multi-employer work leans on ISO 9712 so the credential travels with the technician.