This work is designed to artificially create test specimens with defects that behave the same way as real-function defects when observed by NDT technologies. Thus, the understanding of the detection limitations of NTD methods is needed. In this study, real, "as real" and artificial defects were compared by Ultrasonic phased array technology. Fatigue defects, which belong to the most common structural issues, are investigated. Measurements have revealed significant differences in amplitude of ultrasonic echo from fatigue cracks in distinct phases of crack propagation. Studied specimens with "as real" defects have demonstrated their quality as testing, calibration or training tool for operators. More realistic test bodies will increase ultrasonic test result reliability.