Eli5: Why were the Boeing Max 9 planes immediately grounded but not the Max 8’s?

Question

I don’t understand why regulators immediately grounded the Max 9’s, but it took two Max 8 crashes before they were grounded.

In: Other

Answer 1

Boeing blamed pilot error on the earlier crashes caused by MCAS runaway trim. It took time before the FAA realized Boeing was requiring only the skimpiest of training on the system (to preserve the “same type rating”) so this “pilot error” was going to be endemic and not a one-off.

But there’s zero doubt that this recent problem is a mechanical problem that cannot possibly be pilot error. There is no way for a pilot to command that plug to open. If it opens, it’s because something is built wrong or maintained wrong.

And the likelihood of it being the airline’s maintenance’s fault after purchase is low because this is a rather new plane that hasn’t been in the airline’s hands for more than a few months.

So it’s *very* likely that something was done wrong in manufacturing or designing the plane. The purpose of the grounding and inspections is to find out if it’s a problem across all the planes or a problem on just this one plane.