The anti-stall system that pilots battled before the crash of a Lion Air-operated Boeing 737 Max in October was also likely to have been activated before 157 people were killed this month on a flight of the same model leaving Addis Ababa, the Ethiopian Airlines chief executive has said.

The new feature of the 737 Max, the manoeuvring characteristics augmentation system (MCAS), has been highlighted by an investigation into the previous crash, in which 189 people were killed when their plane went down in the Java Sea off Indonesia 12 minutes after takeoff.

Ethiopian’s boss, Tewolde GebreMariam, told the Wall Street Journal he believed MCAS was also “to the best of our knowledge” in play for the brief duration of flight 302 from Addis Ababa.

MCAS automatically forces the nose of the plane down to prevent stalling, and was introduced to compensate for the new position of engines on the 737 Max model. A preliminary report into the Lion Air crash has suggested the combination of incorrect sensor readings and MCAS contributed to the plane diving into the sea.

GebreMariam’s reported remarks are the first from a senior official close to the flight to confirm that MCAS was operating, although he said that only the investigation would provide conclusive evidence. The black boxes are in Paris being analysed by France’s air crash investigation bureau, the BEA.

In an official statement released by Ethiopian on Monday morning, GebreMariam said he did “not want to speculate as to the cause” but “many questions on the 737 Max airplane remain without answers”.

He again stressed the modernity of the airline’s safety and training systems, which include a dedicated simulator for the 737 Max, adding: “Contrary to some media reports, our pilots who fly the new model were trained on all appropriate simulators. The crews were well trained on this aircraft.”

Despite the crash, he said: “Let me be clear: Ethiopian Airlines believes in Boeing.”

The vote of confidence is likely to be welcomed by Boeing, whose stock has been battered since the two crashes. The company will brief more than 200 global airline pilots, technical experts and regulators this week on software and training updates for the 737 Max. It is expected to build enhanced warning devices as standard into every plane. A cockpit light to notify of faulty sensors had been installed in many planes – including the American Airlines fleet – but was not purchased by Lion Air or Ethiopian.

On Friday, the Indonesian carrier Garuda became the first airline to scrap its order for the model, blaming a lack of public trust. It has taken just one of 50 737 Max planes it has on order, worth up to $6bn on listed prices.

The current global fleet of 387 planes remains grounded as investigations continue. The cockpit voice recorder recovered from the wreckage of the Lion Air plane has shown that the pilots were consulting a handbook to understand why the 737 Max continued to lurch downwards in the final minutes before it crashed into the sea.