Families of the victims, regulators and travellers around the world have been waiting for signs of whether the two crashes are linked, and the extent to which Boeing technology and the actions of the Ethiopian Airlines pilots played a role.
Ethiopian investigators did not blame anyone for the crash, in line with international rules requiring civil probes to focus on technical recommendations for safer flight.
Nor did they give a detailed analysis of the flight, which is expected to take several months before a final report due within a year.
But in a clear indication of where Ethiopian investigators are directing the attention of regulators, they cleared the pilots of using incorrect procedures and issued two safety recommendations focused on the recently introduced aircraft.
They suggested that Boeing review the flight control system and that aviation authorities confirm any changes before allowing that model of plane back into the air.
"Since repetitive uncommanded aircraft nose down conditions are noticed ... it is recommended that the aircraft control system shall be reviewed by the manufacturer," Dagmawit said.
The nose-down commands were issued by Boeing's so-called MCAS software. The preliminary report into the Lion Air disaster suggested pilots lost control after grappling with MCAS, a new automated anti-stall feature that repeatedly lowered the nose of the aircraft based on faulty data from a sensor.