Criticisms of the crew's actions were "seriously misinformed" Tewolde GebreMariam told the BBC.
He was responding to claims from a US congressman that mistakes by the pilots were a factor in the aircraft's failure.
The Boeing 737 Max went down just six minutes after take-off in Addis Ababa.
The loss of Ethiopian flight ET302 was the second fatal accident involving a 737 Max in the space of five months. A near identical aircraft, owned by the Indonesian carrier Lion Air, went down in the sea off Jakarta in October 2018.
Preliminary reports into both accidents have suggested that they were triggered by a flight control system deploying at the wrong time, due to a faulty sensor.
Congressman Sam Graves at a hearing in Washington last month argued that "facts in the preliminary report reveal pilot error as a factor".
He went on to suggest that "pilots trained in the US would have successfully been able to control this situation".
Mr GebreMariam told the BBC that Congressman Graves did not "have the facts in his hands".
The preliminary report, he said, "made it abundantly clear the pilots followed the procedures properly".
The control system, known as MCAS, was meant to operate under very specific circumstances, in order to make the new plane feel more like a traditional 737 to fly.
However, in each accident, it repeatedly forced the nose of the plane downwards, countering the commands of the pilots, and ultimately forced the plane into a dive.
Prior to the second crash, Boeing had alerted airlines to the existence of MCAS, and set out instructions on how it could be deactivated. Mr Graves believes the crew of ET302 failed to follow those instructions properly.
At the same congressional hearing, the acting head of the US Federal Aviation Administration appeared to agree with those criticisms, describing some of the crew's actions as "unfortunate".
Boeing itself has repeatedly described the failure of MCAS as a single link in a chain of events that led to both accidents.