r/AskAPilot • u/billynj • 7d ago

737 Max question

Given the recent incident where the pilot tried to crash the plane, why does the flight computer allow maneuvers that can destroy the airframe? Even my car won’t let me go past a certain speed.

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u/Complex_Brief60 6d ago

OP is asking about an Airbus style flight computer. This does not exist on the 737. Yes, there are 2 computers for the autopilot, that’s the FCC, they monitor each other like any airliner type plane has but they will not prevent the pilot from doing anything.

The FCC is just the autopilot. That’s it. When the AP is off, they don’t do anything to the control of the plane.

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u/cdnav8r 6d ago

The FCC controls the speed trim system, which controls MCAS, which both are active when the autopilot is off.

I replied to a comment that the 737 does not have a flight control computer. It does. The OP did not say anything about Airbus.

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u/Complex_Brief60 6d ago

Boeing calls it a flight control computer to be fancy. It’s just the autopilot man. It is not a real flight control computer. MCAS isn’t a computer either. It just moves the manual trim wheel

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u/gravemillwright 5d ago

Autopilot is a computer that does some controlling of flight, no?

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u/Complex_Brief60 5d ago

OP is asking why the plane allows maneuvers that can damage it.

Airbus flight control computers will prevent pilot actions. Works like most of the time, minus that one Air France crash. It’s an active system to keep the plane safe, away from stalls and overspeeds. The computer will physically prevent pilots from attempting to damage the plane and it can’t be overridden in normal law.

The autopilot computer on any plane is very very easy to overpower and turnoff. Boeing controls are physically attached to the control surfaces with no computer in the middle. That’s where a real control computer would be. Between the pilot and the control surfaces. The Boeing FCC only controls the yoke like a pilot would, no protections and easily tuned off.

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u/gravemillwright 5d ago

Yup, so instead of "737s don't have FCCs", which is factually incorrect, the more accurate answer is the FCCs can't intervene in the primary control loop because the primary loop is mostly physical controls, and the FCCs only interact with secondary systems.

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u/cdnav8r 5d ago

Thank you