For automatic control of manufacturing processes, continuous monitoring of the manufacturing result is necessary. In order to make continuous statements about the quality of the product, non-destructive testing methods with a data-recording rate adapted to the pultrusion process are necessary. Air-coupled ultrasound is a method that can be used for non-transparent, thin composite materials. In order to be able to evaluate the applicability in in-line testing, a defect catalogue with flaws often occurring in pultrusion was compiled. By manipulation of the pultrusion process, artificial defects were induced into the pultruded bars in order to be able to subsequently determine the testability with air-coupled ultrasound. With the help of this examination, it is possible to evaluate the detectability of defects with air ultrasound, depending on the type of defect.