A number of airlines have now grounded their Boeing 737s after an Ethiopian airlines crash on Sunday killed all 157 people on board.
It was the second crash in five months involving a 737 Max 8 – the first being a Lion Air accident in Indonesia last October. The 737 Max 8 aircraft has only been in commercial use since 2017.
US plane maker Boeing is facing questions, but experts warn it is too early to say what caused the latest disaster.
According to Ethiopian Airlines, the plane, flight ET302, crashed just six minutes after it left Addis Ababa, 60km south-east of the capital.
The pilot had reported difficulties and had asked to return to Addis Ababa, the airline said.
"At this stage, we cannot rule out anything," Ethiopian Airlines CEO Tewolde Gebremariam told reporters at Bole International Airport in the capital.
Passengers from more than 30 countries were on board the flight, including 32 Kenyans, 18 Canadians, and seven Britons.
At least 19 victims were heading to a session of the UN Environment Assembly in Nairobi, which began with a minute's silence on Monday.
In Ethiopia, Monday has been declared as a national day of mourning.