> What MCAS actually did was not modifying the pilots inputs, but adjusting the stabilizer trim in certain scenarios.
But MCAS had enough control authority to override the pilots' inputs; the pilots of both crashed aircraft were desperately trying to pull the nose up, but couldn't because MCAS had put in so much nose down trim that they couldn't counteract it.
> The pilots do have direct control over the stabilizer trim, and have always had the ability to disable the electronic system in case of stabilizer trim runaway. This was not new to the MAX, and would have effectively disabled MCAS.
The ability to disable the automatic stabilizer trim system was not new to the MAX, yes.
What was new to the MAX was that, unlike previous 737s, disabling the automatic stabilizer trim system would also disable the manual electric stabilizer trim system, so that the only way to adjust the trim would be by using the mechanical trim wheel. And it was possible for MCAS to adjust the trim into a range where it was mechanically impossible to adjust it back using the mechanical trim wheel.
But MCAS had enough control authority to override the pilots' inputs; the pilots of both crashed aircraft were desperately trying to pull the nose up, but couldn't because MCAS had put in so much nose down trim that they couldn't counteract it.
> The pilots do have direct control over the stabilizer trim, and have always had the ability to disable the electronic system in case of stabilizer trim runaway. This was not new to the MAX, and would have effectively disabled MCAS.
The ability to disable the automatic stabilizer trim system was not new to the MAX, yes.
What was new to the MAX was that, unlike previous 737s, disabling the automatic stabilizer trim system would also disable the manual electric stabilizer trim system, so that the only way to adjust the trim would be by using the mechanical trim wheel. And it was possible for MCAS to adjust the trim into a range where it was mechanically impossible to adjust it back using the mechanical trim wheel.