Boeing faces a “serious challenge” to win back the confidence of regulators and airlines, its CEO has said, as the planemaker 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 some 171 Max 9 jets to be grounded for several weeks – has sparked the biggest safety crisis for Boeing since the cr ...