[breadwinner]

Is there never a case where it is cheaper + better to start over? I think sometimes there is. The design of 737 MAX was flawed from the get-go. They made the engines bigger because bigger engines run hotter and burn less fuel. Ordinarily this would require the fuselage to be raised as well, so that the bigger engine can fit under the wing. Instead they changed the position of the engine. Instead of being hung under the wing, as in earlier models, the engines have been moved forward and upward, potentially leading to an aerodynamic stall under certain circumstances. Instead of going back to the drawing board and getting the airframe hardware right, Boeing relied on something called the ‘Maneuvering Characteristics Augmentation System,’ or MCAS. [1]

It's just poor design. If software fails, then any plane should be designed to have a neutral center of gravity in order to give the crew the greatest amount of time to recover from the loss.

[1] https://spectrum.ieee.org/how-the-boeing-737-max-disaster-lo...

[Retric]

Never is a loaded word.

It’s almost impossible for a completely fresh design to be safer on day one. There’s so many different ways to fuck up many of them are counterintuitive because nobody ever considers if someone could install this backwards until someone does. 20+ years of debugging written with people’s lives tests just about everything in a way engineers never really think about

[breadwinner]

The difference here is that 737 MAX has a flaw (forward positioning of the engine) that cannot be fixed as a "bug".

[ianburrell]

The flaw was fixed with MCAS. The problem that caused the two crashes was that pilots weren't trained on the new system because Boeing wanted to act like it was the same plane. The pilots didn't know what was going on or how to disable MCAS when it started misbehaving because of bad sensor.

With training, improved systems, and redundant sensors, MCAS should be safe. There are other planes that have similar systems. And there procedures for disabling bad sensors or misbehaving sensors.

I'm not sure if MCAS is necessary, there is some indication it is only there to mimic older 737 and plane would be safe without it and with training.

[Retric]

You can definitely treat it as a design flaw and fix it without impacting most systems.

Designers need to make radical changes before cockpit windows would need to be updated. That specific example may not seem like much but there’s a lot of safety critical engineering that goes into such things and yet design flaws where still uncovered.

[breadwinner]

Sure you can bring over the "good parts" of the old plane, but if this design flaw is fixed then it is essentially a new plane. They will no longer be able to pretend it is the same as the old 737s (and that's what got them into trouble).

[Retric]

When you say “parts” it’s really complex systems. The 737 family of aircraft has gone through many revisions over 50+ years at this point.

The original 737-100 was 61,994 lbs empty and the 737-900ER was more than 50% heavier at 98,495 before they started calling them MAX. The 900ER was in many ways a radically different aircraft but got there through a long list of incremental changes leveraging the past.

That’s not to say new designs can’t be quite safe. The much newer A320 family are some of the safest aircraft flying with only 38 hull losses and 1505 fatalities, but do not mistake good design for inevitability.