The Federal Aviation Authority (FAA) ordered the temporary grounding of certain Boeing 737 MAX 9 aircraft operated by U.S. airlines or in U.S. territory.

“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 Emergency Airworthiness Directive (EAD) requires operators to inspect affected aircraft before further flight. The required inspections will take around four to eight hours per aircraft.

The EAD will affect approximately 171 airplanes worldwide.