The fragility of prescribed performance control (PPC) is discussed for the flight control of the waverider vehicles (WVs) via simulation analysis. Firstly, the motion model of WV is described and the state variables are defined. Then, particular characteristics of WV dynamics including nonlinearity, non-minimum phase, anti-saturation, and anti-disturbance are qualitatively or quantitatively analyzed. On this basis, the fragility defect of the existing PPC protocols, caused by actuator saturation and sudden disturbance, is pointed out, which indicates a new research direction for the next development of PPC.