The question might have at least crossed the minds of the 87 passengers on the revamped Boeing 737 MAX's first public flight Wednesday following a 20-month grounding after two fatal crashes.

US authorities last month gave the green light for the plane to return to service after upgrades in the wake of the two calamities that killed 346 people.

Wednesday's promotional American Airlines voyage between Dallas, Texas and Tulsa, Oklahoma was intended to reassure the public before American resumes commercial service on the jet on December 29.

The trip began with American flight attendants reviewing security procedures before distributing bottled water.

As he welcomed passengers, pilot Pete Gamble testified to the plane's safety and reliability.

"The systems changes, the scrutiny the airplanes are going through, plus the training that we've enforced, has really brought back the confidence level," Gamble told AFP after the flight. 

"It needed to go through the scrutiny. It did."

Before flying the MAX, each American pilot is required to undertake a two-hour training course on a computer tablet, followed by an hour of flight simulator training, followed then by two hours with a colleague where pilots react to different flying scenarios.

Aside from some turbulence along the way, Wednesday's 50-minute flight to Tulsa proceeded uneventfully.

Throughout, passengers donning face masks because of the coronavirus and separated by a seat due to social distancing measures betrayed no obvious anxiety.

The everyday passenger not steeped in aviation will see no obvious markers of the MAX. The safety cards in the pockets of the seats give only the numbers 737, though the wheel labels the jet as a "73-8x."

American has said that all customers who buy tickets on the plane will be notified of flights employing the MAX. The carrier will provide alternative trips to passengers who don't want to fly on the plane.

"Safety is our number one priority," said American Chief Operating Officer David Seymour. "There are no exceptions."

Strict regimen

In Tulsa, Roger Steele, a 34-year veteran at American Airlines, is overseeing the process of readying the jets so they can return to the skies.

Steele said he has always loved the Boeing 737 MAX and was present when the giant US carrier received its first jets.

All the aircraft must go through four days of intense work before being cleared for service.

Teams work 24 hours a day at a warehouse on two planes at a time to check the pressure on the tires, the hydraulic systems, the motors and other plane parts. 

Staff also update software systems in the cockpit and modify plane cables.

All of these steps are mandated by the US Federal Aviation Administration, which last month authorized the plane to return to service under strict protocols.

"We started the very same day," Steele said. 

Around 20 MAX planes are still on the tarmac.

Maintenance crews were on hand "to make sure that this aircraft is ready for your family, for my family, all of our loved ones, to get on board," said Erik Olund, who manages the maintenance base.

His teams neatly took care of the planes while they were grounded, with staff members checking the humidity in the plane's fuel tanks or installing pillows in the motors to prevent animals from getting in.

Pilots repeat the mantra: There is no risk to flying on the 737 MAX.

The MAX will make its first commercial flights in 20 months between Miami and New York on December 29.