Boeing faces a “serious challenge” to win back the confidence of regulators and airlines, its CEO has said, as the aircraft maker faces intense scrutiny after a cabin panel blowout. Dave Calhoun acknowledged the business has “much to prove” since a brand-new 737 Max 9 jet was forced into an emergency landing earlier this month. The dramatic incident during an Alaska Airlines flight – which prompted 171 Max 9 jets to be grounded for several weeks – has sparked the biggest safety crisis for Boeing since the crashes of two of its Max 8 jets, in 2018 and 2019, in which 346 people were killed. As it reported its quarterly earnings on Wednesday, Boeing declined to provide Wall Street with guidance for the year ahead, stating that its “full focus” was on working to “strengthen quality” at the company. In a letter to employees, publicly released alongside the results, Calhoun described “tough and direct conversations” with airlines, regulators and politicians in recent weeks. “They are disappointed and we have much to prove to earn our stakeholders’ confidence,” he wrote. “There is no message or slogan to do that.” Officials have expressed more than disappointment. The US Federal Aviation Administration (FAA) has ramped up oversight of Boeing, and last week barred the company from increasing production on its Max manufacturing line. “This won’t be back to business as usual for Boeing,” warned Mike Whitaker, the agency’s administrator, who stressed it would not approve any production expansion “until we are satisfied that the quality control issues uncovered during this process are resolved”. Such scrutiny “will make us better”, Calhoun told staff. But it has also prompted anger from Boeing’s customers, and prompted some, such as United Airlines, to weigh plans to leave a forthcoming Boeing jet, the Max 10, out of its fleet. Boeing posted a 10% rise in revenue to $22.02bn in the fourth quarter, which finished days before the Alaska incident on 5 January. Its net losses narrowed from $663m to $30m over the same period. “We’ve taken significant steps over the last several years to strengthen our safety and quality processes,” Calhoun wrote, “but this accident makes it absolutely clear that we have more work to do.” The CEO nevertheless insisted that Boeing’s management still has “every confidence” in the company’s recovery. “We have a serious challenge in front of us – but I know this team is up to the task.”