Boeing Chief Executive Officer Dave Calhoun took responsibility for last week's mid-air blowout on an Alaska Airlines flight, vowing "complete transparency" as the aircraft maker grapples with the fallout.

"We're going to approach this (by) number one acknowledging our mistake," Calhoun told employees at a safety meeting on Tuesday.

The statement is Boeing's first public acknowledgment of error since the incident.

The company-wide meeting was called after a plug on an unused exit door seal blew off while the plane was climbing, depressurizing the aircraft at 16,000 feet (about 4.9 kilometers).

The plane, with the 171 passengers and six crew members on board made an emergency landing back to the Portland International Airport with no serious injuries.

The Federal Aviation Administration (FAA) grounded all Boeing 737 Max 9 aircrafts for inspection, leading to hundreds of canceled flights.

The National Transportation Safety Board (NTSB) investigator-in-charge examines where the door plug flew off Deutsche Welle

Vow of transparency

Calhoun committed to working with the US National Transportation Safety Board (NTSB), which is currently investigating the incident.

"We're going to approach it with 100% and complete transparency every step of the way," Calhoun said, as per remarks released by the company.

The NTSB is "as good as it gets," and "I trust every step they take, and they will get to a conclusion," he said.

NTSB investigators on Monday, suggested that the part was not affixed adequately. Meanwhile, Alaska Airlines and United Airlines — the only two carriers which use Boeing's 737 Max 9 planes — reported loose hardware on some of their Boeing 737 Max 9 planes during initial inspections.

Working on detailed inspection

The FAA on Tuesday said it was still working with Boeing to finalize the detailed inspection instructions for grounded planes.

"Boeing offered an initial version of instructions yesterday which they are now revising because of feedback received in response," the FAA said.

"Upon receiving the revised version of instructions from Boeing the FAA will conduct a thorough review."

Calhoun said the aviation giant was working with both regulators and airlines to ensure such an incident "can never happen again."