Ethiopian Airlines flew passengers on a Boeing 737 MAX plane on Tuesday, but opinions are divided on its first flight using the model since a crash nearly three years ago forced various countries' regulators to ground the fleet.

In March 2019, a flight to Nairobi crashed in a field six minutes after take-off from Ethiopia's capital Addis Ababa, killing all 157 passengers and crew. It was followed by another accident five months earlier, when a jetliner of the same model crashed in Indonesia, killing 189 people.

The accidents exposed a problem with the plane's Maneuvering Characteristics Augmentation System, and the model was grounded worldwide, costing Boeing some $20 billion and prompting court cases that exposed shortcomings with the certification process.

Tuesday's demonstration flight had journalists, diplomats and officials on board and was initially scheduled to reach neighboring Kenya but remained within Ethiopia due to poor weather, officials on board said.

While airborne, the airline's acting CEO Esayas Woldemariam told reporters that commercial flights would resume after the demonstration.

"We made sure everything is in order, now we are doing... a demo flight so to speak. It is after this that we are availing it to commercial aviation," said Esayas.

Some relatives of those killed in the Ethiopian Airlines crash were angered by the decision to resume flying the 737 MAX.

"I will never fly in a MAX and certainly if I find myself booked into a MAX, I will have to cancel that flight," said Tom Kabau, a Kenyan lawyer who lost his 29-year-old brother George in the crash.

A lawyer for victims of the Ethiopian Airlines Flight 302 accused the airline of having failed families on many fronts.

"The families of those who lost loved ones in the crash... are extremely disappointed with the lack of leadership at the airlines that has failed them in many ways," Robert Clifford of Clifford Law Offices, said in a statement to Reuters.

He added that the status of the airline's own investigation into the crash "remains unknown" after nearly three years.

Ethiopian Airlines said in a statement on January 22 that the decision to resume flights came "after intense recertification" by multiple regulatory bodies.

"We have taken enough time to monitor the design modification work and the more than 20 months of rigorous rectification process ... our pilots, engineers, aircraft technicians, cabin crew are confident of the safety of the fleet," the airline's CEO Tewolde Gebremariam said in a December statement.

Ethiopia is among the last countries to return the 737 MAX to service. The model is already flying in the United States, Europe, Australia, Japan and Indonesia. 

Two of China's carriers reportedly completed 737 MAX's test flights in January after the model regained airworthiness from the country's aviation authority late last year.

On January 21, a MAX 8 belonging to China Southern Airlines, the largest 737 MAX operator in the country, took off from its headquarters city Guangzhou in south China's Guangdong Province and touched down after three hours and 33 minutes in the same city, according to aviation data provider VariFlight. 

In a two-hour-and-52-minute flight, Hainan Airlines flew one of its 737 MAX from Taiyuan, capital of north China's Shanxi Province, to its base city in Haikou of south China's Hainan Province on January 9.

None of these flights carried passengers.

(With input from Reuters)