The Boeing 737 Max blowout has sparked a rare wave of public criticism from airline CEOs and the FAA, with harsh words flying about its quality control

• Airline CEOs have criticized Boeing in the wake of the Alaska Airlines blowout.
• Alaska's CEO said he was "mad" and United threatened to change its order book.
• While the FAA criticized Boeing's production problems as "unacceptable."

The Alaska Airlines blowout in January has subjected Boeing to a torrent of criticism from airline executives.

A 737 Max 9 jet, delivered just 66 days earlier, lost its door plug in midair — forcing an emergency landing. The Wall Street Journal reported that the plane left Boeing's factory missing key bolts designed to keep the plug in place.

As bosses expressed their frustrations, the CEO of Boeing Commecial Airplanes apologized. "We have let down our airline customers and are deeply sorry for the significant disruption to them, their employees and their passengers," said Stan Deal.

"We are taking action on a comprehensive plan to bring these airplanes safely back to service and to improve our quality and delivery performance," he added. "We will follow the lead of the FAA and support our customers every step of the way."

From Boeing's biggest customer to regulators' strong words, the incident has sparked a wave of public criticism, a rarity in the aviation sector.

Scott Kirby, United Airlines

United is Boeing's biggest customer and the largest operator of the 737 Max 9, with 79 such jets in service.

18 days after the incident, the morning of United's fourth-quarter earnings, Scott Kirby spoke to CNBC and didn't hold back — even suggesting he could change the carrier's order book.

"The Max 9 grounding is probably the straw that broke the camel's back for us," he said. "We're gonna build an alternative plan that just doesn't have the Max 10 in it."

Boeing initially forecast the largest version of the 737 Max would be certified by 2022, but Kirby believes it could be delayed as much as five years. United has 150 Max 10 jets on order.

Kirby told CNBC he has confidence in Boeing staff to resolve its problems, but he wants to see "actions to really get the manufacturing process back to the high levels of quality and consistency that historically existed."

Ben Minicucci, Alaska Airlines

Later that same day, the CEO of Alaska Airlines appeared on NBC to share his thoughts on the saga.

"It makes me angry," said Ben Minicucci. "Boeing is better than this. And Flight 1282 should never have happened, should never have happened."

He added it was only thanks to a "guardian angel" that nobody was killed in the blowout: the seven unoccupied seats on the 178-capacity jet luckily included those next to the gaping hole.

Minicucci told NBC he was further angered by the fact that Alaska discovered loose bolts on other Max 9 jets during inspections after the grounding.

"It makes you mad that we're finding issues like that on brand-new airplanes," he said.

Michael O'Leary, Ryanair

Ireland-based Ryanair is the world's biggest airline by market capitalization, and Europe's biggest by passenger numbers, and is famous for its cheap tickets and outspoken boss.

Days after the incident, Michael O'Leary told the Financial Times, "both Airbus and Boeing, certainly Boeing, need to significantly improve quality control."

"We have been loud in our complaints about the lack of quality control of Boeing over the last two years," he said in a press conference a week later.

O'Leary pointed to issues like finding a stray wrench under the floor of one Boeing jet.

However, he has also offered some support to Boeing, giving his backing to CEO Dave Calhoun. O'Leary said comments from other airline bosses "weren't helpful," and offered to take on United's Boeing orders if it wants to delay or cancel them.

Tim Clark, Emirates

Like O'Leary, the Emirates president is not shy of criticizing others in the industry — albeit less flamboyantly. Speaking to the Financial Times, his criticism of Boeing was measured but strong.

Tim Clark said Boeing is "in last chance saloon" and "they've got to put the house in order."

He called on the company's board to prioritize manufacturing processes over finances, and pointed to the fact that Emirates engineers were invited to oversee production lines as a sign of its struggle.

"The fact that we're having to do that is testament to what has happened. This would not have been sanctioned in the old days," he said.

Although, Clark added that he had confidence in Boeing to "restore itself to its former glory."

Less than two months before the Alaska Airlines blowout, Emirates placed a mammoth $52 billion order for 95 Boeing 777s and 787s.

Mike Whitaker, FAA

When the Boeing 737 Max experienced its first crisis following the deaths of 346 people in two crashes in 2018 and 2019, the Federal Aviation Administration was criticized for taking too long to ground the planes.

In fact, Donald Trump stepped in and told the FAA to ground the jets. So it makes sense that this time around, the regulator took swift action and hasn't minced its words about Boeing.

As the FAA increased its oversight of Boeing's production line, Administrator Mike Whitaker said: "The quality-assurance issues we have seen are unacceptable."

And after the regulator cleared the Max 9 to return to the skies, Whitaker added: "However, let me be clear: This won't be back to business as usual for Boeing."

He said it wouldn't let Boeing expand production of the Max, "until we are satisfied that the quality-control issues uncovered during this process are resolved."

Pete Buttigieg, the transportation secretary, backed the FAA's actions, saying it "is holding Boeing accountable for its production quality problems."

"We can never take the nation's aviation safety record for granted," he added.