The 737 MAX's larger CFM LEAP-1B engines are fitted farther forward and higher up than in previous models. The aerodynamic effect of its nacelles contributes to the aircraft's tendency to pitch up at high angles of attack (AOA). The MCAS is intended to compensate in such cases, modeling the pitching behavior of previous models, and meet a certain certification requirement,[41] in order to enhance handling characteristics and thus minimizing the need for significant pilot retraining.[42][43][40]