NDI based envelope protection in icing encounters.

Existing envelope protection system in icing encounters normally involve real-time prediction of critical flight parameters or by calculating the allowed reference value of the pilot input, which may bring extra computational burden or need large amount of previous work. The paper proposes using nonlinear dynamic inversion (NDI) based controller to obtain the available deflection of the control surface, thus to limit the angle of attack within the stall angle. Two different cases with constant and time varying icing severity are considered to validate the effectiveness of the proposed envelope protection method. Numerical simulation results show well performance of the envelope protection system. Comparing with existing envelope protection method, the proposed method gives an active way to ensure flight safety.