Posted on 04/30/2019 9:33:26 AM PDT by WhoisAlanGreenspan?
Juan's latest update is well worth checking out. He attempts putting the unstable design theories to rest.
Also Boeing Shareholder Press Briefing
Decision reversed by appeals court.
I believe that is not true.
From the preliminary report: "At 05:38:44, shortly after liftoff, the left and right recorded AOA values deviated. Left AOA decreased to 11.1° then increased to 35.7° while value of right AOA indicated 14.94°. Then after, the left AOA value reached 74.5° in ¾ seconds while the right AOA reached a maximum value of 15.3°. At this time, the left stick shaker activated and remained active until near the end of the recording.Also, the airspeed, altitude and flight director pitch bar values from the left side noted deviating from the corresponding right side values. The left side values were lower than the right side valuesuntil near the end of the recording."
There is a tolerance between left side and right side WRT airspeed readings and altitude readings. If the disagreement is within tolerance, the warnings are not displayed. The preliminary report never mentions that the "Airspeed Disagree" warning or "Altitude Disagree" warning are ever displayed. The pilots have no reason the execute the Airspeed Disagree checklist.
If you can provide a reference that the Airspeed Disagree or Altitude Disagree warning are displayed, please provide the URL.
IMHO, if either warning had been displayed, the preliminary report would have stated it.
The report mentions several deviations and includes low resolution chart, all of which indicate deviations.
In the case if the Lion Air, AoA deviation was 20 degrees which set off IAS. The Ethiopia plane had a deviation of about 75 degrees which would surely set off the IAS.
Additionally, there was an over-speed alarm on for about two minutes before the crash.
Very good to hear, it seems like most of the time the decisions stand.
I have re-read the Lion Air prelim report and cannot find where the Airspeed disagree warning illuminated during the accident flight. On the previous flight, IAS and ALT Disagree and FEEL DIFF PRESS faults were noted. The pilots performed the checklist items and landed safely.
AOA and Pitot/Static systems are independant. The sensors gather their respective data and place the data on an ARINC data bus. A difference between left and right Angle of Attack (AoA) of about 20° should not cause any type of Airspeed warning.
The Ethiopia plane had a deviation of about 75 degrees which would surely set off the IAS.
Nope...prelim report has no reference to Airspeed disagree warning being illuminated.
Here's what I don't understand...75° AoA is impossible to achieve in an airliner. At the speeds the aircraft was flying, 75° AoA would rip the wings off. Boeing could have easily included logic in the MCAS software to disregard impossible AoA. Any AoA above 25° would be rejected as a sensor malfunction and the other AoA sensor would then be used.
The new MCAS software will fix the problem as MCAS will be disabled whenever there is an AoA disagree warning.
Additionally, there was an over-speed alarm on for about two minutes before the crash.
The pilot response to this is SLOW DOWN (Throttles-Idle). IMHO, this indicates the pilots were task saturated, improperly trained, and lacked basic airmanship skills.
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