The chief executive officer of American plane manufacturer Boeing has taken responsibility for a near-catastrophic plane incident in Portland, Oregon last week.

“We’re going to approach this number one acknowledging our mistake,” CEO Dave Calhoun told employees Tuesday at a safety meeting called after Friday’s emergency landing of an Alaska Airlines flight when one of the plane’s panels blew out mid-flight, six minutes after taking off from Portland International Airport.

Calhoun committed to working with the National Transportation Safety Board, which is probing the incident.

“We’re going to approach it with 100 percent and complete transparency every step of the way,” he said.

US regulators with the Federal Aviation Administration have grounded 171 737 MAX 9 planes with the same configuration as the Alaska Airlines jet.

The affected panel, a door plug, is used to fill an unneeded emergency exit in planes.

NTSB investigators suggested Monday night that the part was not affixed adequately.

On Tuesday, the FAA said it was finalizing detailed inspection instructions for grounded planes.