Boeing Faces Backlash From Airline Chiefs

Airline bosses have lashed out at Boeing over a streak of safety and production problems — loose bolts, a discarded wrench found under the floorboards, delayed shipments — as scrutiny over the company’s manufacturing processes intensifies.

“I am angry,” Ben Minicucci, the chief executive of Alaska Airlines, told NBC News on Tuesday after the carrier found “many” loose bolts while checking its fleet of Boeing 737 Max 9 jetliners after a door plug flew off one of the planes in midair on Jan. 5. “My demand on Boeing is, What are they going to do to improve their quality programs in-house?”

After the incident, the Federal Aviation Administration grounded around 170 Max 9 jets until they are inspected and said it would investigate whether Boeing failed to ensure that the plane was safe.

Scott Kirby, the United Airlines chief executive, told CNBC on Tuesday that the Max 9 grounding was “probably the straw that broke the camel’s back for us.” He also criticized production delays of another Boeing aircraft the airline had ordered, the Max 10, saying he doubted the planes would be delivered anytime soon.

“We’re going to at least build a plan that doesn’t have the Max 10 in it,” Mr. Kirby said.

It’s an uncommon escalation: Airlines and their manufacturers typically enjoy a symbiotic relationship, with carriers often competing with one another to place orders for new jets, which can have yearslong wait lists. Along with the European aircraft manufacturer Airbus, Boeing makes the majority of the world’s commercial jets, limiting options for airlines that are seeking new planes.

“Boeing’s maintenance and production faults over the last few months are unprecedented, so it’s not surprising that airlines are beyond frustrated and taking unprecedented behavior themselves,” said Xavier Smith, director of energy and industrials research at AlphaSense.

But at this point, criticizing Boeing may be the most that the chief executives can do to vent their frustration without stoking panic about plane safety.

Jonnathan Handshoe, an airline analyst for CFRA Research, said the public admonishments amounted to reassuring passengers that the airlines were concerned about safety while impressing upon Boeing the severity of the crisis.

“It’s more like: ‘Hey, we’re calling you out. This is an issue. It needs to be fixed because there are clearly quality control issues,’” Mr. Handshoe said.

Stan Deal, chief executive of Boeing’s…