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Driver Assist Technology

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Ed Dartford

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Location
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Driver Assist Technology (Letter to Editor)

As a pilot, and father of a Boeing 737 pilot, I have been closely following investigation of the recent crashes of 737MAX planes. It is evident that the underlying cause of these crashes is computer software that Boeing used to overcome adverse aerodynamic characteristics of the MAX version of the 737. They wanted the MAX to fly like earlier versions of the 737 which would make it much easier for the FAA to certify it as safe, and would eliminate any need to retrain pilots, all of which boils down to saving money.

At high power levels the big new engines cause the nose of the plane to pitch up. If uncorrected this might lead to a stall (wings lose lift) and the nose to drop dangerously. Of course, pilots are taught from the very first lesson how to not stall, and what to do if you do stall. But Boeing thought that they needed to automatically take the action that any pilot would instinctively take and push the nose down. The software that does this is named MCAS (Maneuvering Characteristics Augmentation System).

MCAS determines if it needs to pitch the nose down by a signal from an AOA (Angle Of Attack) device which is like a little weathervane on the side of the plane. Anyone who has a weathervane knows that they are prone to get stuck and indicate the same wind direction all the time. If the AOA device, or its electronics, incorrectly indicates that the plane is climbing too steeply, and a stall may happen it erroneously pitches the nose down at a much higher rate than normal trim adjustments. There is chaos in the cockpit with many alarms sounding off. Not every pilot can figure out what is going on and flip the one switch that would turn off MCAS (remember that Boeing and the FAA said that pilot retraining was unnecessary). If the pilots succeed in overcoming what MCAS is doing, it does it again, and again, until the plane is traveling way above its maximum certified speed and is unrecoverable.

My reason for writing this letter is to point out that increasing automation of all kinds of vehicles is a safety hazard: cars in particular. Boeing thought they were improving safety with MCAS, but MCAS has killed hundreds of people. How many people must be killed in cars swerving into the ditch or oncoming traffic because the car computer thought, incorrectly, that they were leaving their lane. I will not buy a car with “driver assist” technology, or, if I must, there better be a way to turn the damn thing off.

Boeing and the FAA will figure out what is wrong with MCAS and come up with a fix for the 737MAX. But a more significant lesson is to be learned from the 737MAX crashes.

Software may introduce risk which is greater than what the software tries to eliminate. General Motors needs to have a long talk with Boeing.
 

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