A commercial aircraft does not utilize direct input to control surfaces. Hydraulics & mechanics - in some cases electronics, aka ‘fly by wire’ - move control surfaces based upon pilot input. Some older models still utilized cables, but in the case of the elevator, depending upon the model the elevator is primarily controlled by a mechanism called the jackscrew, a mechanism with no manual override.
In the case of the 737 MAX - from which I presume your question originates - a single sensor inputs to the computer to determine angle of attack, prompting the computer to override manual input to move the elevator to push the nose down corresponding to sensor readings of the nose angle. The reason for the pitching up & down is rooted in pilot attempts to override the computer, for which it’s now asserted that there are 1 or 2 switches.
If the jackscrew were to jam - as in the case of Flight 261 - the aircraft is doomed. There’s a good video of jackscrew operation at this source I hate to reference:
https://en.wikipedia.org/wiki/Alaska_Airlines_Flight_261
That’s the simple explanation if I understand the nature of your question. The mechanics are the same, T-tail or not.
I’ve mistakenly neglected to click ‘chat’ as well; just ping the moderator to change it.
In the case of the 737 MAX - from which I presume your question originates - a single sensor inputs to the computer to determine angle of attack, prompting the computer to override manual input to move the elevator to push the nose down corresponding to sensor readings of the nose angle. The reason for the pitching up & down is rooted in pilot attempts to override the computer, for which it’s now asserted that there are 1 or 2 switches.
Lots to unpack there. First of all, there’s not one but two AOA sensors. Second, inputs from the AOA sensors are not all the imputs that determine stall override conditions by the MCAS. Third, as in Lion air we will probably find the pilots made futile attempts to hand fly the aircraft when doing any one of three things may have saved the plane.
One, disengaging the MCAS. Done by simply switching off a toggle on the center console located by the right seat pilot (the pilot with 200 TT flight hours). Two, Scrolling the pitch trim handwheel located next to each pilot (visual and audible indicators alert the pilots to trim being adjusted). Manual adjustment of the pitch trim disables the MCAS for five seconds each time. Third, engaging the autopilot and letting the autopilot fly the plane (last choice, AP may not have been configured for climb out). Engaging the AP disengages the MCAS.
Training error, but Boeing is culpable too.