I'm attaching 3 normal flights profiles, 1 normal speed and altitude data vs the profile of the crashed Ethiopian and its speed and altitude readings.
The difference between them is obvious.
Could it be that being, maybe, early and first flight of the day the cover of the pitot tubes where not removed? It has happened before. The latest happened to a MH in Brisbane Australia. Poor preflight checks by engineers and pilots. They both missed it.
This could explain the lack of speed and altitude during almost 2 minutes of the doomed plane. Then in very short time speed of 250-383kts.
During take off roll they were caught by surprise and missed* the 80 kts callout. First reaction of a ill trained crew to fly Airspeed Unreliable Speed NNC or junior crew ( *FO had,its being said, 200hrs) was to level off to gain speed. Once speed increases rapidly he retract flaps to avoid exceed VMO placard. Speed jumps very fast. To control it commander pulls abruptly to control speed and then a real high AOA of attack is reached. Having a problem he requests to turn back...
MCAS kicks in when: High angle of attack, manual flight, flaps up and in a turn.
Assuming pilots did all this in sequence, it might triggered the MCAS. And sadly in this case, it worked exactly the way it was designed to work. To avoid an upset triggered by a unreasonable maneuver by pilots or environment.
Then they kept fighting MCAS, why? Investigation will tell the probable cause...
its just a thought...