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Old 14th Nov 2018, 17:25
  #1204 (permalink)  
Join Date: Sep 1999
Posts: 542
the STS and the MCAS appear to be different. This 737 hit the water going very fast. The STS should have been trimming back. The MCAS, if the AoA was erroneously high, would have been trimming forward. The MCAS is only fitted to the Max.
No I dont concur...the plane was going fast but HAL (ie FCC A) thought it was near to a stall trimmed down...hence the previous commanders observation of " STS trimming the wrong way"..AMM NG data implies that providing the controlling FCC is being fed corrupt data(CAS/AoA etc) and the crew dont disable AP stab trim(or ALL trim as per Boeing AD),then it will happen in a NG as well.....Boeing admit that it is MCAS that caused the unwanted trim in 610...ergo,MCAS is STS with some differences(software tweaks) cant be too different due type certificate commonality concerns as discussed.Maybe the exact sequence of 610 cant happen in a NG we need more data.

Design?As stated you cant design perfection so you have to design the best available considering the fallibilities of pitot-static system....somebody pointed out that Airbus have 3 AoA vanes and use a voting system but this was proven fallible at Perpignan...Bernd said its better to have a false stall warning than no stall warning...agreed. Airbus PRIM on Qantas 72 provided an elevator nose down with 610 Boeing provides a nose down trim.Silver has argued quite well that perhaps Airbus is right in this matter.Fokker put the circuit breakers for these tactile/aural warnings close to the pilots,others bury them on the panels behind the pilots.Whatever the nuances and differences design is perfect and the crew remain the last and best(hopefully) line of defense.
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