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

There was a good amount of speculation after the first Max 8 crash that it was the result of pilot error, but after the 2nd crash it became clear there was an issue with the aircraft, so it was grounded.

With the Max 9 it was very clear it wasn’t a pilot error issue and a malfunction of the aircraft, so they were grounded sooner.