The return of Boeing’s 737 Max has been delayed again. On Tuesday, the company said it did not expect regulators to approve the jet to fly again until the middle of the year. American Airlines, United and Southwest had already taken Max flights off their schedules until June, and if this new timeline holds, it would further push back when the plane will be available for commercial flights.
The announcement reflects Boeing’s new appreciation for the challenges facing the company in its effort to persuade regulators that the Max is ready to fly. Boeing and the Federal Aviation Administration have continued to find new flaws with the Max that go beyond an automated software system known as MCAS. The software contributed to two accidents, in late 2018 and early 2019, that killed 346 people and led to the worldwide grounding of the Max in March.
But the new estimate is conservative and intended in part to give Boeing some leeway with airline customers, who became frustrated over the past 10 months after the company repeatedly missed its own optimistic deadlines for the plane’s return to service, according to three people familiar with the matter. If regulators find no new problems with the plane, they could lift the grounding by the spring, the people said.
Once the plane is cleared to fly, it will take airlines weeks to reintegrate them into their commercial schedules. The three United States carriers that fly the Max — American, United and Southwest — had already pushed back Max flights until June. They did not immediately change those schedules in response to Tuesday’s announcement.
“Returning the Max safely to service is our No. 1 priority, and we are confident that will happen,” the company said in a statement. “We acknowledge and regret the continued difficulties that the grounding of the 737 Max has presented to our customers, our regulators, our suppliers and the flying public.”
Late last year, Boeing discovered a potential problem with wire bundles on the plane, which were placed so close together that an electrical short could cause a catastrophic accident. In assessing the issue, the company recently identified about a dozen places in the Max where wire bundles may need to be separated, including in the electrical bay under the cockpit, according to two people familiar with the situation who spoke on the condition of anonymity to discuss internal matters. The company is still analyzing whether it needs to separate the wire bundles, the people said.
Boeing is also working through a separate software problem that prevented its flight control computers from turning on. And this month, the company told airlines that it would recommend flight simulator training for pilots before flying the Max. That could delay the return of the plane even after regulatory approval since it will take longer than the iPad lesson the company was originally planning to give pilots.
The company needs to reach several key milestones before the Max is cleared to fly. International regulators must conduct flight simulator tests with pilots from airlines around the globe. Boeing still needs to conduct a certification test flight with the F.A.A., the Max’s final exam with regulators, which also may happen by the end of next month, according to two people with knowledge of the process.
The grounding of the Max is the worst crisis in the 117-year history of Boeing, which is the largest manufacturing exporter in the United States. It has cost the company billions of dollars, led to the ouster of its chief executive and disrupted the global aviation industry. Last month, Boeing announced that it would temporarily halt production of the Max, a move that rippled through its network of thousands of suppliers. One supplier, Spirit AeroSystems, announced that it was laying off 2,800 employees.
The mass cancellation of flights caused by the grounding has led to steep losses for airlines, which have scrambled to fill key routes without a workhorse jet. Several airlines, which pay roughly $100 million each for the Max planes, have reached settlements with Boeing to compensate for those losses.
Boeing’s announcement on Tuesday was a departure from the company’s handling of the crisis under its previous chief executive, Dennis A. Muilenburg, who was prone to making overly optimistic projections about how quickly the plane would fly again.
Boeing prepared the estimate on the Max’s approval for its own financial planning in advance of the company’s report on quarterly earnings next week, said Gordon Johndroe, a company spokesman. It did not expect any layoffs as a result of the move. (Boeing employs more than 130,000 people, in all 50 states.) The company also wanted to publicize the new timeline before United, Southwest and American Airlines report quarterly earnings this week “to make sure they had our most recent estimate,” Mr. Johndroe said.
Airline stocks, which opened the day down on fears of the potential impact of a deadly viral outbreak in China, continued to slump. United Airlines ended the day down 4.4 percent and United 4.2 percent. Delta dropped by 2.7 percent. Trading of Boeing shares was temporarily halted after CNBC first reported the news of the company’s new timeline on Tuesday. The stock ended the day down 3.3 percent.
Mr. Muilenburg’s replacement, David Calhoun, formally stepped into the chief executive role last week. For its part, the F.A.A. said it was continuing with the process of getting the plane approved to fly again.
“We have set no time frame for when the work will be completed,” the agency said in a statement.
Matt Phillips contributed reporting.