(The Hill) — After being grounded earlier this month to go through inspections, Boeing 737 Max 9 jetliners are returning to the skies weeks after a midair blowout occurred on an Alaska Airlines flight.

Alaska Airlines began to resume commercial flights on the Boeing 737 Max 9 jetliners on Friday afternoon with a flight from Seattle to San Diego, the airline announced last week. The airline said the planes will only return to the air “after the rigorous inspections are completed and each plane is deemed airworthy according to [Federal Aviation Administration] requirements.”

The FAA laid out the process to return the Boeing 737 Max 9 aircraft to service last week, saying that it approved a “thorough inspection and maintenance process” that will be performed on each of the 171 grounded Boeing 737 Max 9 aircraft. The jets were grounded just hours after a door plug on an Alaska Airlines flight blew off while in the air, prompting the plane to make an emergency landing earlier this month.

Alaska Airlines said it expected all of its grounded aircraft to be completed by the end of the month, which will allow it to fully operate its flight schedule. The airline also noted that they will work with customers who are “not comfortable” flying on the 737 Max 9 jets as they return to service, saying they will try to move them to a different flight on another aircraft.

The Associated Press reported that Boeing Commercial Airplanes president and CEO Stan Deal told employees last week that the company’s top goal is to help airlines resume normal operations.

“Our long-term focus is on improving our quality so that we can regain the confidence of our customers, our regulator and the flying public,” he wrote in a message.

“Frankly, we have disappointed and let them down. We are deeply sorry for the significant disruption and frustration for our customers, some of whom have been publicly and unfairly criticized,” he added.

The AP also reported that United Airlines flew its first resumed passenger flight on 737 Max 9 on Saturday morning from Newark, N.J. to Las Vegas. United Airlines is the only other airline to use the 737 Max 9 besides Alaska Airlines.

The Associated Press contributed reporting.