Alaska Airlines cancels 230 flights as the 737 Max 9 is grounded after mid-flight door blowout

• Alaska Airlines canceled 230 flights on Sunday and Monday, with more expected this week.
• United Airlines also canceled 270 flights following the FAA's directive.

Alaska Airlines said it's canceling 230 flights after the Federal Aviation Administration grounded certain Boeing 737 MAX 9 jets.

170 of the cancelations were on Sunday, while the airline expects more through the first half of this week.

It added that the grounding "has significantly impacted our operation."

United Airlines, the biggest operator of the single-aisle jet with 79 in service, canceled 270 flights on Saturday and Sunday, FlightGlobal reported.

The FAA grounded certain 737 MAX 9 aircraft on Saturday, the day after an Alaska Airlines flight had to make an emergency landing.

A deactivated emergency exit called a plug door was torn off midair from the fuselage of an Alaska Airlines 737 MAX 9, which was only delivered to the airline last October.

The plane landed safely with no serious injuries, although the National Transportation Safety Board warned it could have been "much more tragic" if someone was seated next to the plug door.

The airline then temporarily grounded its fleet of MAX 9s for inspections. 18 returned to service before the FAA's announcement, which re-grounded them.

The FAA's Emergency Airworthiness Directive requires operators to inspect the affected aircraft, which will take four to eight hours each.

On Sunday, the NTSB announced that a school teacher had found the missing door in his backyard. Two cellphones were also recovered, including an iPhone that still worked despite the 16,000-foot fall.

The NTSB said the plane had three separate pressurization warnings in the weeks before the incident. Alaska Airlines restricted it from flying long distances over water as a result, although the NTSB chair said the warnings could be unrelated.