No agency has provided a lot of details.
Ethiopian Airlines Flight 302 crashed on the morning of 10 March after taking off from Addis Ababa to Nairobi, Kenya, killing 157 people. The plane was carrying passengers from all over the world, many of whom were working for the United Nations.
Lion Air Flight 610 crashed into the Java Sea in Indonesia on October 29, after taking off from Jakarta. The 189 people on board are dead. The plane was scheduled to travel one hour to Pangkal Pinang on Bangka Island.
Both were Boeing 737 Max 8 aircraft
The Boeing 737 Max 8 was a new model unveiled with great fanfare by the American aviation giant about two years ago. The airline has also produced a Max 9 and plans to offer Max 7 and Max 10 models, with model numbers based on the number of seats.
According to the FAA, about 350 Boeing 737 Max 8 aircraft are in operation worldwide and belong to 54 operators.
Both aircraft used the same software
The aircraft were equipped with automated flight software called the Maneuverability Enhancement System (MCAS), a relatively new feature of Boeing Max aircraft.
AOA sensors transmit to aircraft computers information on the nose angle of the aircraft in relation to the airflow above and under the wings to help determine if the aircraft Plane is about to stall.
Jean-Paul Troadec, the former head of the French Aviation Accident Investigation Bureau, told CNN that he had noticed flaws in the system.
"I think the design of this system is not satisfactory because it relies only on a sensor," he said. "In the event of a failure of this sensor, of course, the system does not work, in which case it may be difficult for the pilot to overreact to the system."
Boeing chief executive, Dennis Muilenburg, announced Monday that a software update and corresponding driver training for the 737 MAX would be published "soon" and would address concerns discovered as a result of the Lion Air crash .
Both aircraft crashed shortly after takeoff
The flight of Ethiopian Airlines collapsed six minutes after takeoff.
The Air Lion plane crashed 13 minutes after takeoff.
Both aircraft had experienced crews
The International Civil Aviation Organization, a UN agency, recommends that commercial pilots have a minimum of 150 hours. The FAA requires commercial pilots to have 1,500 hours.
Both pilots reported problems
The report states that the MCAS system responds to incorrect data transmitted by an AOA sensor. A different crew experienced the same problem on a Denpasar-Jakarta flight the day before, but he had disabled the MCAS and took manual control of the plane, the paper said.
The Ethiopian Accident Investigation Bureau intends to issue a preliminary report within 30 days.
CNN's Veronica Stracqualursi, CN Patterson, Anna Cardovillis, Kara Fox and Dakin Andon contributed to this report.