We can't see the wood for the trees.
We've got so immersed in MCAS that we're missing the point. Its not MCAS,its the UAS.
This one was just a faulty sensor(not even UAS) Captain's side.They could have engaged AP B,pulled Capt's stick shaker cb,and flown to NBO(no just kiddin).
But thats all it was.....,a failed sensor.
FO gets some disagree flags but his side is good,so is ISFD.And yet the stick shaker and the master caution and the Captain's PFD flags all conspire to make it seem dire.Only the Captain's
shaker was active so they know immediately its not a real stall.
ISFD agrees with FO ASI which agrees with IRS GS....an experienced FO would nudge the skipper@Looks like your side is down,shall I take it?"
We had one poster come on and say he'd climb to MSA and run the Boeing UAS NNC bla bla bla.
This was not UAS.
UAS comes in many forms and can be a nasty scenario on a dark night in IMC.If you're in cruise,I prefer the old Boeing NNC(ie do nothing).
The new NNC is there to cover the possibility you were not in stable flight prior to UAS.After takeoff,you need to make a diagnosis quickly to establish what you're facing....is it single side?is it a
sensor?is it a genuine pitot-static blockage and which one is it,pitot or static....the aeroperu crew had blocked statics so altimeter registered no climb and ASI undereads on climb out.It was night but VMC.If they had climbed to 1500' using radalt as altimeter and IRS GS as speed reference, they would have landed safely after a visual circuit but...you need to have that info and diagnosis in the memory
database.Its not something you can intuit in the moment.
The worst thing they did was climb away from Lima as they lost their altitude reference and their speed reference became less accurate the higher they climbed.
MCAS is the presumed culprit....but MCAS alone didnt bring this aircraft down.Nor the Lionair.It was the crew's inability to diagnose what type of UAS failure they were facing and failure to just simply
fly the plane.If MCAS would activate alone,any crew would simply counter-trim and cut off its electrical supply without much thought. But combine it with a "confusing" UAS scenario and shakers and
warnings and bingo..you get a smoking hole in the ground.
So these UAS scenarios have to be taught in the classroom and sims to all crews so that when the time comes they can make a diagnosis and take the right action.Boeing tell you nothing,they just give you a flight attitude and thrust setting to follow.Pilots have to be trained more on these UAS scenarios before they kill again.
Aeroperu,birgenAF447 and the 2 MAXs,and others.....
Re manual trim...have we had any engineering input as to just when manual trim no longer becomes available in the flight envelope?Is it primarily speed dependent,stabilizer positon-dependent,yoke dependent,or a combination of all 3?
Where is FCENG 84?
Last edited by Rananim; 8th Apr 2019 at 22:29.