As United Airlines and Alaska Airlines cancelled flights through Tuesday, the Federal Aviation Administration also said it will require another round of inspections before it will consider putting the jets back in service.

Under more stringent supervision, the regulator will audit the Boeing 737 MAX 9 production line and suppliers and consider having an independent entity take over from Boeing certain aspects of certifying the safety of new aircraft that the FAA previously assigned to the planemaker.

How many planes are being grounded?

The regulator said Monday the grounding would be lifted once they were inspected.

On Thursday, the FAA announced a formal investigation into the MAX 9, which the FAA said had “significant problems” and noted Boeing’s history of production issues.

The National Transportation Safety Board (NTSB) is investigating if the MAX 9 jet in the Alaska episode was missing or had improperly tightened bolts.

‘Are there not enough quality control checks?’

The FAA wants to see “where these breakdowns could happen. Are there not enough quality control checks? Are they not in the right places? Is the order of assembly creating some issues?,” he said.

“I think it may be an option where there’s a higher level of confidence, where we have more direct oversight ability, and where the folks doing certain critical inspections don’t have a paycheck that’s coming from the manufacturer.”

FAA says tighter control ‘inevitable’

“Now everyone is starting to raise an eyebrow and make sure the Ts are crossed and the Is are dotted.”

The FAA also launched an outside review of Boeing’s safety culture in January 2023.