American Airlines on Tuesday launched the first commercial flight of a Boeing 737 MAX in the United States since the plane was grounded worldwide following two deadly crashes that killed hundreds and plunged the airplane manufacturer into crisis.

The MAX was Boeing's top-selling aircraft, and the company struggled through the nearly two years that the plane was barred from skies globally, a situation made worse by the sharp slowdown in travel caused by the Covid-19 pandemic.

Boeing has worked with regulators to address technical issues and improve pilot training on the MAX, leading countries to allow it to return to service, starting with a domestic flight by Brazilian budget carrier Gol earlier this month.

The first of the US carriers to return the plane to service, American flight 718 carrying about 100 passengers took off from Miami bound for New York's La Guardia airport around 1544 GMT.

"This is an aircraft that has been more highly scrutinized than any ever before. We're very confident that this aircraft is the safest in the skies," the airline's president Robert Isom said before the flight's departure.

CNBC reported the plane was filled with a combination of aviation enthusiasts and people who just happened to be flying between the two cities, one of whom told the broadcaster they initially felt apprehension about being aboard.

"But I quickly forgot about it and it's been a really easy flight," the unnamed passenger said.

The plane landed in New York at 1812 GMT, according to the airport, and departed back to Miami more than an hour later in a flight the airline said had nearly sold out of its 172 seats.

United Airlines is due to return the MAX to its US fleet with flights beginning on February 11, and Southwest Airlines, which has the largest MAX fleet, said it will restart service in the second quarter of 2021.

American Airlines will fly the first 737 MAX commercial flight in the US, traveling from Miami to New York
American Airlines will fly the first 737 MAX commercial flight in the US, traveling from Miami to New York AFP / Cooper NEILL

The return comes after the Federal Aviation Administration in late November cleared the jet to fly again following upgrades to its software and new pilot training protocols.

The MAX crisis began with a 2018 crash of the jet in Indonesia, followed by another in March 2019 in Ethiopia, which killed a total of 346 people and saw the aircraft taken out of service across the globe.

Airlines canceled numerous orders for the plane -- but as it neared a return to service Boeing reported new orders in recent weeks, indicating the company's fortunes may be reversing.

The return has not been entirely smooth, however. Families of the crash victims continue to oppose allowing the aircraft to fly, saying it is unsafe.

"A corporation that continues to manipulate due diligence and to cut corners in matters of life and death should not be trusted with human life," said Zipporah Kuria, whose father died in the crash in Ethiopia.

"As the families who paid the cost and have been forced to eat the fruit of Boeing's deceptive patterns, this will not end well."

An Air Canada MAX flying last week from Arizona to Montreal with three crew members on board experienced an engine problem that forced it to land in Tucson.