US plane maker Boeing is facing questions after an Ethiopian Airlines 737 crash on Sunday killed all 157 people on board.
It was the second crash in five months involving a 737 Max 8, and comparisons are being drawn with a Lion Air accident in Indonesia last October.
In response, a number of airlines have now grounded all planes of the same model.
However, experts warn it is too early to say what caused the latest disaster.
The investigation will be led by Ethiopian authorities co-coordinating with teams of experts from Boeing and the US National Transportation Safety Board.
An urgent priority for investigators will be to find the plane’s two cockpit recorders – one for data and another for pilots’ voice recordings.