Originally Posted by
L39 Guy
If one rolls down the runway with both engines providing the advertised thrust (94%), the airspeed cross check at 80 indicates no disparity, and the aircraft is rotated normally at Vr with both airspeed indicators working normally then rotated to a climb attitude and the engines continue to turn and burn, then any erroneous stall warning has to be ignored and treated as such. That is why manufacturers provide nominal pitch/power settings to insure a stall free climb or cruise while it gets sorted out. In fact, I had the same stick shaker after take-off many years ago on the 737-200 after lift-off; yes, it gets your attention but if the attitude of the aircraft is ok and the engines are running fine then it cannot be a bona fide stall but an erroneous indication.
If the crew thought it was a stall, then the stall recovery should have been implemented - it was not and in fact they (Ethiopian) tried to engage the autopilot, a definite no-no in a stall.
So even setting aside the MCAS issue later, sadly this all points to training and experience to handle a pretty basic emergency. And that points back to the airline and the CAA who are responsible for that.
Maybe you should read about the background a little bit?
ADD, Addis Ababa Bole Airport, 2334 meter [7625 ft] elevation/ASL.
DIA, Denver International Airport, 1655 meter [5431 ft] elevation/ASL.
ADD is more than 2200 feet higher than DIA. It is among the top for the list of notoriously "HOT AND HIGH" airports in the world.
It goes without saying that the aircraft there will have a different TO routine, notably requiring a higher thrust and a longer run, plus high terrain avoidance.
We have to also remember the MCAS "deadly potion" as well: AOA False high & Autopilot Off & FLAP Zero.
105 seconds into their flight, the AOA was already gone mad [IAS disagree, ALT unreliable, stick shaker], but they MUST go FLAP ZERO ASAP to gain Altitude at this higher elevation. And, they needed all the thrust.
They knew they had to play around with the flap and/or the Autopilot to keep MCAS at bay- at least one of these had to be ON to hold off the MCAS "deadly potion".
So, these are their only choices:
1. Going with with Flap On|Autopilot Off.
2. Going with Flap Off|Autopilot On.
3. Going with Flap On|Autopilot On.
Obviously going with Flap On (i.e. [1] and [3]) would go against their effort to gain altitude. That would leave them with (2). So, they turned on the AP, not because they wanted the AP, but it was because their circumstance FORCED them to turn AP on.
When the AP was turned on, they bought themselves about 60 seconds [actually only about 20 "clean" seconds because during FLAP ZERO] to continue gaining the altitude but they were still only about 300-500 feet off the ground [8000+ ft - 7626]...
In other words, the MCAS "deadly potion" constraint made their already difficult TO situation [a high elevation TO, a long run, a stick shaker, an IAS disagree, an ALT unreliable, other warnings] much much worse.