Alaska Airlines emergency: Boeing CEO says company 'acknowledging our mistake'

Boeing CEO Dave Calhoun told employees on Tuesday that the company is "going to approach" last week's Alaska Airlines midair emergency by starting with an acknowledgement of "our mistake."

"We're going to approach it with 100% and complete transparency every step of the way," Calhoun said during a meeting with employees at the 737 production facility in Renton, Washington. "We are going to work with the NTSB who is investigating the accident itself to find out what the cause is."

The focus of National Transportation Safety Board investigation into Friday's emergency is focused on the single aircraft, but could be broadened as more is learned, board Chief Jennifer Homendy said.

"However, at some point, we may need to go broader. But right now we have to figure out how this occurred with this aircraft," Homendy said Tuesday on ABC News' "Good Morning America."

The door plug fell off the plane, a Boeing 737 Max 9, around 5:11 p.m. local time last Friday as the aircraft with 171 passengers, including three babies and four unaccompanied minors, had climbed to 16,000 feet after taking off from Portland International Airport, according to the NTSB.

The Federal Aviation Administration said Tuesday, "Every Boeing 737-9 Max with a plug door will remain grounded until the FAA finds each can safely return to operation."

"The safety of the flying public, not speed, will determine the timeline for returning the Boeing 737-9 Max to service," the FAA said.

Alaska Airlines said Tuesday evening it is awaiting instructions from Boeing and the FAA on the inspections that need to be completed to get its 737 Max 9s back in the sky.

"When we are able to proceed with the inspection process, all aircraft will be thoroughly inspected in accordance with detailed instructions provided by the FAA in consultation with Boeing," Alaska said. "Any findings will be fully addressed."

"No aircraft will be returned to service until all of these steps are complete," the airline added.

Boeing said it continues to be in "close contact" with its customers and the FAA about required inspections of certain 737 Max 9 planes.

"As part of the process, we are making updates based on their feedback and requirements," the company said in a statement Tuesday.

The fittings at the top of the door plug fractured, Homendy said. The NTSB examination has shown that those fittings were fractured, allowing the plug door to move upward and outward, she said.

"We don't know if the bolts were loose. We don't know if bolts were in there fractured or possibly the bolts weren't there at all," she said. "We have to determine that back in our laboratory."

On Monday, United Airlines said it had found loose bolts on its 737 Max 9 fleet during inspections ordered after Friday's incident involving an Alaska Airlines flight.

The Federal Aviation Administration said Saturday it was temporarily grounding certain Boeing 737 Max 9 aircraft operated by U.S. airlines or in U.S. territory until they were inspected. The FAA said the pause would affect about 171 planes worldwide.

Homendy said Tuesday she would feel safe flying on a 737 Max 9 now.

"I would feel safe flying right now," Homendy said. "Our aviation system is the safest in the world."

The White House also said Americans should "feel safe flying" following the incident.

"FAA’s number one priority is the safety of Americans," White House press secretary Karine Jean-Pierre told reporters during a briefing on Tuesday. "The fact that these Boeing aircraft are going to be grounded is important, right? That is taking the safety of Americans first."

Asked if the White House primarily sees this as a Boeing or FAA issue, she said, "We don’t know yet."

"We have to do an investigation to see exactly what occurred here," she said.

ABC News' Amanda Maile, Sam Sweeney, Bill Hutchinson, Jon Haworth and Justin Gomez contributed to this report.