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

The door that blew off is literally walled off in the type of configuration Alaska is using. The door is available if an airline wants/needs it, but the way Alaska set up the cabins in the ones they had shipped to them they didn’t want or need that door. So it was bolted shut and the cabin wall was installed with no door access from the inside.

That means what happened was either sabotage or a mechanical problem, and may impact any planes built to the same cabin configuration as only the paint would change (and not the bolts and stuff). There was simply no way a person could have been screwing around while the plane was in flight and done something that would blow out a door to which they had no access, it can’t be crew error. The door is not able to be opened by a computer (though there may be sensors telling the computer if the door is open or closed). Therefore it is not a computer problem. That leaves only a physical problem with the airframe itself, a mechanical issue.

The only way to find out whether this was a one-off freak incident or something widespread (for instance, a batch of bad bolts from the bolt maker) is to take every plane in the entire fleet apart and look for instances of the same problem, which means grounding the fleet. And to that end — at least five more instances of the same problem have been found that would have happened eventually with more likely to be announced as the inspections continue.

The others you are asking about were a software issue that was initially blamed on pilot error, and pilot error is a training problem that doesn’t generally require grounding an entire fleet. For pilot training you require more hours craft-specific hours with a training pilot on board and/or time in a flight simulator (also configured for the specific aircraft). Once it was realized that the problem was in the airplane and not the pilots, the fix/grounding order was issued.