The promotional flight, which included AFP among other media, departed near 1610 GMT from Dallas and landed and landed about 50 minutes later in Tulsa, Oklahoma, after encountering some turbulence along the way.

In Tulsa, American's teams of mechanics, technicians and engineers outlined their processes for readying and upgrading the jets following the lengthy grounding. Pilots were also on hand to explain new training protocols required by federal air safety officials.

The MAX had been a cash cow for Boeing prior to the Lion Air and Ethiopian Airlines crashes that together claimed 346 lives. Those calamities plunged the aerospace giant into a crisis worsened by the coronavirus and its devastating impact on commercial air travel.

After the lengthy grounding following two deadly crashes, the US Federal Aviation Administration in mid-November cleared the MAX to return to service following upgrades to the plane and pilot training protocols.

Brazilian authorities have also okayed the MAX to fly again, while European officials are expected to approve the MAX's return by the end of January 2021. China remains the main mystery as far as when it expects the MAX to fly again.

American Airlines plans an initial commercial flight on December 29.

The carrier is undertaking a charm offensive to reassure consumers the jet is safe. On Tuesday, American's chief executive, Doug Parker, along with his wife, took a flight on a MAX.

Three more test flights with employees are planned before the first commercial flight, an American spokesperson told AFP.

Boeing 737 MAX takes flight after 20 months grounded following deadly crashes
Boeing 737 MAX takes flight after 20 months grounded following deadly crashes AFPTV / Kacey CHERRY

FAA chief Steve Dickson described the process for recertifying the jet as exhaustive when he officially approved the jet's return. Dickson himself piloted a test flight and said last month he was "100 percent comfortable" with having his family fly in the jet.

Investigations identified a principal cause of the two crashes as a faulty flight handling system that was supposed to keep the plane from stalling as it ascended but instead forced the nose of the plane downward. The FAA required Boeing to upgrade the software connected to this system to address the flaw.

Boeing also plans to establish an operations center to monitor MAX flights in real time.

But those efforts are not enough for families of victims of the crashes, who dismissed the American Airlines flight as a "media stunt," according to Clifford Law Offices, which is representing the relatives in litigation against Boeing.

"The promotional flight is arranged by the American Airlines marketing team simply because the company made the mistake of buying more MAX aircraft than almost any other airline," said Michael Stumo, whose daughter died in the Ethiopian Airlines crash.

"Passengers should avoid this aircraft because others are safer."

With 24 MAX planes in its fleet, American Airlines has the second-largest number of planes, after Southwest Airlines with 34.

Customers canceled hundreds of orders for the MAX this year, but Boeing could see a rebound in interest should the plane again win regulatory approval.

Ryanair and Boeing could announce Thursday additional orders, according to industrial sources who asked not to be identified.

The two companies declined comment.

Shares of Boeing rose more than five percent on Wednesday, making it the biggest gainer in the Dow index.