Aerial view of Boeing planes
An aerial view of several Boeing 737 MAX airplanes parked at King County International Airport-Boeing Field in Seattle, Washington, U.S, June 1, 2022. Reuters

Boeing Commercial Airplanes Chief Executive Stan Deal on Tuesday said the U.S. planemaker will continue to push Congress to pass legislation for the Boeing 737 MAX 7 and MAX 10 to win certification even if a key Dec. 27 deadline passes.

"We're still working obviously and hope something happens this year - got another shot early next," Deal said on the sidelines of an event at its 787 final assembly plant. "We're going to hope Congress does their part of this."

United Airlines Chief Executive Scott Kirby, whose airline has ordered more than 100 MAX 10s, told reporters on Tuesday that he did not think lawmakers would act on the extension until next year.

After Dec. 27, all planes must have modern cockpit alerting systems to be certified by the Federal Aviation Administration (FAA), which could jeopardize the futures of the MAX 7 and 10 or mean significant delays for the new aircrafts' deployment -- unless Congress passes legislation. The alerting requirement does not apply to in-service airplanes previously certified by the FAA.

Kirby said it is the right safety answer to have a common alerting system across the 737 family -- including the MAX 8 and MAX 9s in service. He said United MAX 10 orders "are already delayed but we're assuming it get approved sometime next year."

Congress adopted the requirements after two fatal 737 MAX crashes killed 346 people and led to the bestselling plane's 20-month grounding.

Last month, acting FAA Administrator Billy Nolen said he believed the FAA cannot continue any certification work on the airplanes after Dec. 27 without congressional action.

Asked if the FAA can work on non-cockpit alerting issues if the deadline passes, Deal said: "That's really a question for the FAA to clarify. We've obviously raised that question."

The FAA said on Tuesday that after Dec. 27, "the FAA will cease work on reviews related to the crew alerting system for the 737 MAX-7 and -10 in accordance with our congressional mandate," but did not elaborate.

The White House has taken an interest in the 737 MAX alerting issue in recent days. Officials still think it is possible Congress could attach the extension to pending legislation before the deadline. The White House did not respond to a request for comment.

Boeing said in October it expects the 737 MAX 7 to be certified this year or in 2023. Deal said on Tuesday he thinks the MAX 10 could get certified in late 2023 or early 2024.

Last month, Senate Commerce Committee Chair Maria Cantwell circulated a draft proposal that would extend the 737 MAX 7 and MAX 10 certification deadline and require retrofitting existing planes with safety enhancements. "We're fully prepared to support that proposal," Deal said, defending the request for an extension, "We're just trying to keep the aircraft safe as a design."