Chilling reading by Bjørn at Leeham explaining that the elevator blow back problem - which our excellent Fceng84 explained in details a few pages ago - might have been a significant contributory cause for both of these crashes.
I know all about blowback problems of elevators. It was the most dangerous shortcoming of the fighter I flew, the SAAB J35 Draken. Even more dangerous than its famous “Super stall”, a Pugachev Cobra like deep stall behavior the aircraft would only exit from if you “rock it out” of the stall (more on this some other time). While “Super stall” is scary, Blowback is deadly.
What could have been done?
The only remedy to the blowback induced dive would have been a full nose up trim application, for a long time (throttles to idle and air brake would also have helped). But the reaction to trim is slow and the aircraft was now heading for earth. The reflex is not to trim but to pull for all there is, by both pilots, you have seconds to stop the dive. It didn’t help. If this is confirmed as the scenario for the end of both JT610 and ET302 I wonder why the danger of flying to fast at low altitude, while sorting out a raiding MCAS, was not communicated when the MCAS Airworthiness Directive was released after the JT610 crash. MCAS forcing the stabilator to full nose down should not have doomed JT610 or ET302. Their applied speed margins did. The JT610 crew knew nothing about MCAS and a potential blowback problem. The ET302 crew knew about the MCAS problem but not about the danger of flying to fast while sorting MCAS.
I have checked with longtime pilots of the 737. They have not heard of a Blowback problem when flying at elevated speeds at low altitude.
And before MCAS there was no reason to, it was beyond normal flying practice. But the JT610 investigators saw what can happen when you run into the MCAS rodeo. Why didn’t they warn to keep speeds within normal speed range?
Bjørn at Leeham