Originally Posted by
The Bullwinkle
I’m still really confused as to why the MCAS is being held totally responsible for this crash.
Didn’t this flight and the Lion Air flight both have unreliable airspeed problems immediately after takeoff?
Can somebody please explain how the MCAS system can cause an unreliable airspeed indication after takeoff?
I still don’t understand why a blocked pitot isn’t even being discussed.
I'm really curious why people don't look at the FDR graphs from the Lion Air flight.
They are readily available.
The airspeed difference between left and right side is about 10 to 20 knots.
The FDR readout is not consistent with a blocked pitot.
The pitot readout as well as the static port readout is corrected for AoA slightly, that is were the Airspeed disagree comes from.
This correction for AoA is small so even with the left AoA reading 21 degrees high the magnitude of the error on speed and altitude is there but both are still in the right ballpark.
I've attached the FDR readout from the first pdf report that was available on the Lion Air crash (with some annotations):
In this graph only the left side altitude readout is plotted, in the preliminary report you can see the difference to the side with working AoA:
https://www.flightradar24.com/blog/w...ary-Report.pdf
Note also that the 100-200 ft altitude dip on rotation is present on the Ethiopian ADSB data as well.
(That alone doesn't mean that there the AoA was misreading in that case as well but i makes it more likely in my opinion)