Becoming a field inspector means earning certification in nondestructive testing (NDT) and nondestructive evaluation (NDE) testing methods from a certifying body, or from a company who employs their own field inspectors. There are three levels to certification in nondestructive testing. Level I is most similar to an apprenticeship. Level II brings with it more field experience in your chosen inspection methods. Level III inspectors are authorized to oversee and execute NDT programs.