DALLAS — Twenty months after two fatal crashes led aviation officials to ground the Boeing 737 Max, American Airlines relaunched the aircraft Wednesday with a flight from Dallas-Fort Worth International Airport to a technical operations center in Tulsa for members of the media.

The uneventful trip was piloted by Peter Gamble, who received a smattering of applause when the plane touched down 43 minutes later. And it was designed to address problems of public trust more than any design flaws.

“The confidence starts right here on the flight deck,” said Gamble, a Boston-based pilot and union officer in the Allied Pilots Association who served on the ad hoc committee tasked with returning the Max to flight. “That confidence will translate back to the passengers.”

The Federal Aviation Administration ungrounded the Boeing 737 Max last month. The Max was grounded worldwide after two fatal crashes in less than five months that killed 346 people. Investigators said the crashes — one in Indonesia, followed by another in Ethiopia — occurred because of a design flaw in the flight control system. Investigators later determined that a software flaw and other problems had been overlooked or minimized by company engineers.

American Airlines officials said the Boeing 737 Max’s imminent return to passenger service came about only after an intense and collaborative effort that brought together unions and management and involved almost every employee in the company. Pilots, technicians and maintenance crews worked with federal regulators and Boeing employees to make sure all the plane’s systems are safe, American officials said.

Besides recoding software and making other design changes, the recertification process to get the planes back in the air required pilots to undergo additional training, including at least two hours on a flight simulator.

But the Boeing 737 Max’s return to flight also comes as the airline industry is staggering from the effects of the coronavirus. The number of passengers fell by more than 90 percent in the spring after the pandemic reached the United States. By Thanksgiving, only about 35 to 45 percent of passenger traffic had returned compared with 2019, according to screening figures from the Transportation Security Administration, and airlines have been hemorrhaging jobs and profits.

Meanwhile, bipartisan efforts in Congress are underway to reform an FAA oversight process that delegated broad responsibility to Boeing during the safety certification process. Families of the victims have said they do not believe the plane should be restored to service yet because the company has yet to be fully transparent, including providing crucial technical data on the fixes.

Congress also found that the FAA had certified the Max’s airworthiness without fully understanding how the design changes worked or might affect the aircraft’s safety. The tragedies inflicted enormous damage on the FAA and Boeing, two American institutions with previously sterling reputations. Regulatory, criminal and congressional investigations were opened, and dozens of lawsuits have been filed by the families of crash victims.

The crashes led to calls to reform the FAA’s process for certifying aircraft safety and prompted a shake-up in Boeing’s senior management. International aviation authorities, seeking to reduce their reliance on the FAA, conducted their own detailed recertification work on the plane.

The FAA and the Chicago-based company spent much of the past 20 months not only working to correct the Boeing 737 Max’s flaws but also to restore the public’s trust. FAA Administrator Steve Dickson, a former military pilot who took over the agency in August 2019, flew the jet himself on a test flight before clearing it for flight.

Boeing had opted to redesign the midsize 737, a narrow-body workhorse in production since the 1960s, rather than create a new aircraft from scratch, to hold down costs. The company also wanted to avoid doing anything that might require airlines to retrain their pilots, a measure that would further drive up costs by temporarily removing pilots from passenger service while running them through new maneuvers in flight simulators.

The makeover called for building larger engines and moving them further forward and higher on the wings. But the shift also necessitated changes to the automated flight control system that would keep the aircraft from stalling — a condition that occurs when a plane climbs too steeply and it loses lift.

To compensate, Boeing’s engineers developed the Maneuvering Characteristics Augmentation System (MCAS), a computerized flight control system that would automatically push the aircraft’s nose back down in small increments if the aircraft was at risk of a stall.

But as development proceeded, the company also made several fateful decisions. As the design process continued, the engineers strengthened the MCAS’s response to a possible stall by increasing the increments pushing down on the nose. The design team also relied on only one of the plane’s two “angle of attack” sensors to feed data into the MCAS that would determine its risk of stalling. Once triggered, the system would continue to push the nose down unless the flight crew quickly executed a series of steps to disarm it.

Roger Steele, a manager at American’s Tulsa tech ops center, said Wednesday that the flight control system and the MCAS software have been modified so that two sensors now provide data, not just one. The angle of attack sensors measure the relative position of the plane’s nose and oncoming wind, a crucial measurement for safe flight. Both would have to signal a problem before triggering a response on the MCAS, he said. In addition, the automated response will only occur once, not repeatedly, he said.

“It was always the case that you could shut everything off, and the airplane could still fly,” said Ted Rogachuk, a technical pilot with American Airlines, referring to the automated flight control system. But he said the new design changes and additional pilot training will ensure that the aircraft will perform safely.

Even with flight approval from the FAA, returning the model to service will take time, as airlines remove the planes from storage and retrain pilots. European aviation regulators have signaled that their approval could come later this year.

Steele said even while the planes were in storage following the March 2019 grounding order, crews performed periodic maintenance, running checks on engines, electrical, pneumatic and hydraulic systems. They even rotated the tires.

“These aircraft were maintained as if they were flying the line,” Steele said. “I promise you, this is the most reviewed, most vetted aircraft in the history of American aviation.”

Even so, if customers feel uneasy about boarding a Max, they will be able to switch to another flight at no cost, David Seymour, chief operating officer of American Airlines, told reporters. He said transparent booking procedures would allow passengers to know whether they were scheduled to fly on a Max and give them ample flexibility to switch, even if there are schedule changes. After some noncommercial flights early this month, American Airlines plans to put the Max back in service on Dec. 29 between Miami and New York’s LaGuardia Airport.

“The history of aviation is built around a chain of safety,” Gamble told reporters before takeoff. “When the chain of safety is broken, it’s up to those of us in the industry to mend it.”