Pilots do not have direct servo control of the aircraft if there is any possibility of any computer system adjusting the servos aside from the throw commanded by the sticks held by the pilot.
Reading comments such as:
> The problem was that an indicator light, designed to warn of a malfunction by a system that helps raise and lower the plane’s nose, was turning on when it wasn’t supposed to, the company said.
Implies that there is intrinsically some computer system that continually parses the commanded stick deflection and applies an overlay.
What I am suggesting is a single toggle to make everything shut up and reset all servos to their midpoint all at once in one shot and let the pilot just fly the plane.
I have not seen any evidence that such a system exists. It is the elephant in the room. Airplanes do not need complex electronics to just fly if they are aerodynamically stable, and this plane is more or less stable except that under some conditions it will make the pilot soil their pants at higher AoA, which is where the promises of MCAS come in. Big deal. They can mentally compensate against that manually better than fighting a computer system working actively against your commanded inputs.
I have experienced the joy of a badly tuned PID controller turning my stabilization system into involuntary high speed descent. The fix is always to tell the computer to shut up and just fly the plane 100% manually.
> Implies that there is intrinsically some computer system that continually parses the commanded stick deflection and applies an overlay.
That's not how the 737 works. The 737 is not a fly by wire aircraft. The pilots control the rudder, ailerons, and elevators electrohydraulically; there is no computer filtering. The electric stability trim system, which is what MCAS feeds its input into, controls the trim tabs on the elevators. This does not change anything about the pilots' inputs to the elevators, but it does change the aerodynamics of the elevators in a way that can limit the pilots' ability to control pitch.
> this plane is more or less stable except that under some conditions it will make the pilot soil their pants at higher AoA, which is where the promises of MCAS come in. Big deal.
If the 737 MAX had been a new aircraft type, it would not have been a problem. There might still have been some adjustment needed to meet FAA certification requirements for stick force (basically, the stick force is supposed to increase with increasing angle of attack, so the pilot has to pull harder to keep the nose going up as you get closer to a stall). But there would not have been a need to cobble together anything like MCAS.
The problem was that Boeing wanted the 737 MAX to be certified under the existing 737 type certificate (because otherwise the potential customers wouldn't want it, since they didn't want to have to re-train and re-certify all their pilots), which meant that the stick force as a function of angle of attack had to be the same as for previous 737s. But the new engines on the 737 MAX made the plane aerodynamically different, so the "natural" stick force was different. MCAS was a software kludge to try to change the stick force.
Reading comments such as:
> The problem was that an indicator light, designed to warn of a malfunction by a system that helps raise and lower the plane’s nose, was turning on when it wasn’t supposed to, the company said.
Implies that there is intrinsically some computer system that continually parses the commanded stick deflection and applies an overlay.
What I am suggesting is a single toggle to make everything shut up and reset all servos to their midpoint all at once in one shot and let the pilot just fly the plane.
I have not seen any evidence that such a system exists. It is the elephant in the room. Airplanes do not need complex electronics to just fly if they are aerodynamically stable, and this plane is more or less stable except that under some conditions it will make the pilot soil their pants at higher AoA, which is where the promises of MCAS come in. Big deal. They can mentally compensate against that manually better than fighting a computer system working actively against your commanded inputs.
I have experienced the joy of a badly tuned PID controller turning my stabilization system into involuntary high speed descent. The fix is always to tell the computer to shut up and just fly the plane 100% manually.