Why would they build a plane with a screw that, if set a certain way, would cause the plane to crash?
An airplane has a ‘trim tab’ which adjusts the angle of the nose of the airplane during flight. It is adjusted so the pilot can fly ‘hands-off’ and the plane will maintain straight and level flight. The pilot does not have to fight it through-out the flight.
Think of a car that pills to one side. It would be nice if there were a knob you could turn to eliminate the pull and you wouldn’t have to fight it during the drive.
One exercise during flight training is the instructor adjusts the trim during flight and the student has to maintain straight and level flight in spiteof it. I can just imagine the terror if the trim of a commercial jet full of people is being manipulated by an out of control autopilot going nuts. By all accounts, this is what is happening on these flights. With the plane trimmed full nose-down it would be very hard to pull against it.
nacl
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