The MCAS deflects the horizontal stabilizer four times farther than was stated in the initial safety analysis document.[1] Due to the amount of trim the system applies to the horizontal stabilizer, aerodynamic forces resist pilot control effort to raise the nose. As long as the faulty AOA readings persist, a human pilot "can quickly become exhausted trying to pull the column back".[59] In addition, switches for the horizontal stabilizer trim assist now serve a shared purpose of turning off automated systems such as MCAS as well as the trim buttons on the yoke, whereas in previous 737 models each could be switched off independently. In simulator sessions, pilots were stunned by the substantial effort needed to manually crank the trim wheel out of its nose down setting when the trim assist was deactivated.[60][61][62]