> You're misunderstanding that quote. It's talking about "authority" in the sense of software's authorization to move the trim tab, not the aerodynamic authorit

> You're misunderstanding that quote. It's talking about "authority" in the sense of software's authorization to move the trim tab, not the aerodynamic authority of the tailplane. > The 737 has a 60 year old, very conventional elevator with a trim tab. The tab changes the resting angle of the overall elevator, and thus the "center point" of tailplane force on the airframe. Being out of trim means that the aircraft might naturally want to pitch up or down, and forces the pilot to apply to force to the stick (which moves the elevator, not the trim tab!) to correct it. I don't think so. The 737 has a trimmable horizontal stabilizer. Stab trim moves (and MCAS moves) the big and leading-edge airfoil and not a trailing-edge tab on a trailing-edge elevator control surface: https://my.mixtape.moe/tkyyzt.png https://my.mixtape.moe/tkyyzt.png See https://www.satcom.guru/2018/11/stabilizer-trim.html https://www.satcom.guru/2018/11/stabilizer-trim.html (where i took this image from) for further details.