WASHINGTON, D.C.—The Federal Aviation Administration (FAA) announced on January 6 the temporary grounding of all U.S.-operated Boeing 737-9 airplanes with a mid-cabin door plug installed for immediate inspections.

“The FAA is requiring immediate inspections of certain Boeing 737 MAX 9 planes before they can return to flight,” FAA Administrator Mike Whitaker said. “Safety will continue to drive our decision-making as we assist the NTSB’s investigation into Alaska Airlines Flight 1282.”

The agency determined that an in-flight departure of the mid-cabin door plug resulted in a rapid decompression of Alaska Airlines Flight 1282 and believes the issue is “likely to exist or develop in other products of the same type design.”

Alaska Airlines Flight 1282 departed Portland on January 5, 5:06 p.m. local time and was back on the ground in Portland at 5:26 p.m. after a rear mid-cabin exit door assembly separated from the fuselage in mid-air depressurizing the 10-week-old airplane. All 171 guests and 6 crew members landed back safely.

The Emergency Airworthy Directive (AD) further states that failure of the mid-cabin door plug “could result in injury to passengers and crew, the door impacting the airplane, and/or loss of control of the airplane.” The FAA estimates that approximately 171 airplanes worldwide will be impacted by the containment action.

An Emergency Airworthy Directive, according to the FAA, “is issued when an unsafe condition exists that requires immediate action by an owner/operator.”

Boeing released the following statement in response to the grounding its 737-9 aircraft by the FAA:

“Safety is our top priority and we deeply regret the impact this event has had on our customers and their passengers. We agree with and fully support the FAA’s decision to require immediate inspections of 737-9 airplanes with the same configuration as the affected airplane. In addition, a Boeing technical team is supporting the NTSB’s investigation into last night’s event. We will remain in close contact with our regulator and customers.”

The National Transportation and Safety Administration (NTSB) has scheduled a media briefing on Alaska Airlines Flight 1282 at 8 p.m. local time at the Embassy Suites Portland Airport Hotel.