Modern high-performance materials such as fiber-reinforced plastics are currently indispensable in various industries. Despite higher melt viscosity, recent developments allow the use of thermoplastic materials as a matrix material. Using the pultrusion process, unidirectional thermoplastic tapes can be produced continuously. The materials used in the production of these tapes undergo a quality assurance process in their production. Tapes, however, are often only tested destructively or optically. It would therefore be desirable to have a non-destructive testing method that can detect cracks, inclusions and changes in the impregnation quality quickly and without contact. To determine the impregnation quality, four CFRP tapes with slightly different degrees of impregnation were examined using slanted air-coupled ultrasound transmission. The test specimens were scanned in meandering form and all data were evaluated by means of various specially programmed analysis programs. A tape was arbitrarily selected as OK-Tape and the maximum/minimum amplitude, the mean of the amplitudes and the standard deviations of the entire C-Scan were defined as standard. With an automated evaluation software, quality points could be given for each tape, which were calculated depending on the data of the OK-tape. Using this method, small differences in the total area of the tapes as well as local inhomogeneity, such as holes, were detected. This procedure demonstrates how small differences in tape quality can be detected, although a calibration to an OK-tape is required.