Thank you infrequentflyer789, it's a great day when I can learn a new trick from somebody, particularly enhancing knowledge of advanced google search syntax. A cheat sheet covering all the search operators including the "near" function: Every Google Search Operator You’ll Ever Need.

I agree with your conclusion about finding a reference in the -800 series documentation being a commonality hangover with the MAX. Has anyone else found a reference to the MCAS in a NG only manual?

When flying a 737 heritage and a NG, pilots would be used to seeing the wheels spin at take-off and landing, during the manual parts of the flight.
They were also used to the wheels spinning in apparent opposite direction to the expected, because it was a "Speed Trim" system... so with the new "Max" which, " was not an upgrade that required additional training" the spinning trim wheels are normal....except it would seem, they are not

https://www.marketwatch.com/story/bo...say-2018-11-12

https://www.dallasnews.com/business/...ndonesia-crash

Thank you for this..
This is precisely why the families of all those onboard ought be litigating both Boeing and that imbecile Byron Bailey ' the Captain" who without any fact simply blamed the pilots.

A more forthright and succinct statement is that a non-industry captured regulator would now ground the aircraft, sort the anomaly and let all pilots completed mandated differences training.

https://www.wsj.com/articles/boeing-...d=hp_lead_pos2

may be behind pay wall ...

Power point rangers strike again- a few heads should roll in Commercial ---(IMHO)

Not just in commercial. This reeks of regulatory capture.
The old Boeing was a very different beast, now captured by self interested corporate types, like every other business, spread sheet driven modelling, with an eye on the price of short term incentives and longer term share vesting dates is pretty much how the west was lost.

"Manual flight....you establish this as a recall item during a UAS event.What is manual flight?AP/AT/FD are de-selected.You dont de-select trim....now you may well de-select trim if you recognize STS (or MCAS) responding to bad side data(alertness good airmanship),or you may even disable the AP stab trim as a precaution before STS or MCAS even has a chance to trim(high level of airmanship)....or you may not recognize the insidious trim until its too late due startle factor/panic/inexperience/distraction of tactile aural warnings.So many variables..."

How about grabbing the trim wheel with your hand? Not part of MANUAL inputs?

Do these companies not realise that they have the pension money of people invested in them that are there for the long haul and not for quick gains?

Which is fine, unless you are cognitively overloaded.

MCAS sounds like a SAS to maintain adequate stick force gradient at high alpha. The earlier B737s had a speed trim that worked for a short window of operation in the acceleration phase to ensure that when hand flown the stick force gradient was acceptable, This didn't function at high AOA. The longer fuselage will result in less downwash at the stabiliser than the earlier aircraft, and would otherwise need a larger span tailplane to be incorporated, or strakes etc to be installed. There are other fixes for that, but the easy one is to have an AOA triggered trim bias to offset an unacceptably low inherent stick g, or inadequate positive gradient of the curve.

Presumably the trim system still is observed to move and the trim in motion clacker has not been removed from the SLUF. Forewarned, a crew would be expected to isolate the trim, but that all depends on the remaining cognitive capacity. The CVR will show a saturated crew almost certainly.

As an industry we don't cope well with sensor failures, and as systems become more integrated the problem will grow.

Initially it sounded like an enhancement as it could be done... after some thought, I doubt that is the case at all.

The normal B737 handles high AOA pretty well. I have fully stalled, to the break the 3,4,500's at mid altitude, and at cruise altitude, The mid altitude was in all configurations, and both cases in accelerated and unaccelerated stalls. The Classic at least had straight forward control through the stall, it can have a modest wing drop, but quite manageable, slat rigging makes a difference. The longer bodies have slightly higher effectiveness in pitch control, but the stick force gradient would reduce. Haven't stalled them so cannot comment.

Next crew to have this sort of issue will have some prior knowledge that this crew did not have.

When the NYSE wants monthly updates and quarterly statements, when the fund managers make money long, short up and down it matters little.
AOC responsibility isn't vested with CEOs, it rests with underlings.
Teams of legal ensure the corporation is protected. The Warsaw Convention limits payouts, meaning that with the appropriate insurance the 'corporation' continues on.
To truly understand the disconnect in the modern corporation is to look right into the eye of the MBA. It knows how to tell you the price of everything (which is then minimised by outsourcing or contracting) but is not in the slightest concerned with the cost of anything. When incentive is structured, these managers cut for the short term, as their incentives are short term.
As the Esso Longford gas explosion Royal Commission demonstrated managers hoped it didn't happen on their shift.
The modern day airline management know the price of everything, they cut until it breaks hoping that the point of failure happens when the other guy is in charge.
As NASA found out with the Challenger, the Normalisation of Deviance is costly.

That Boeing withheld pertinent information ought concern all pilots. It would appear the unions have noticed the significance.
The FAA must act but will continue twiddling its thumbs hoping that nothing else goes wrong...
After all there is a lot riding on the commercial success of this product. You could almost bet the airlines are lobbying as are Boeing not to do anything as the 'commercial impact' will be substantial. The FAA ought be focused on the impact of that aircraft in the sea and the lost souls.

They put in MCAS in case the plane is not going to behave in manual flight the way pilots will expect it to. Now, if you have to disable the MCAS, the plane is not going to respond the way you have expected a 737NG to respond when flying manually and it will be more prone to stalling.

Re post 1085
 

​​​​​Absolutely.

How did Boeing push these aircraft through certification without through oversight.

Do they get dispensation to do it themselves??

I think it's fair to say this tragedy will become a battlefield for many lawyers. Oh BO.....

.

Going back a bit ...... the problem SEEMS to have arisen due to a single (?) AOA sensor failure. This then SEEMS to have activated the stick shaker on the side of the aircraft associated with that failed sensor , which happened to be the PF's side (correct ?) In addition this single failure then gave rise to the MCAS starting the POSSIBLE disastrous changes in trim.

IF that is basically correct.

1: It has been stated on here that there were two AOA sensors on the plane, so how did the FCS decide which one was at fault ? IF they had had, say, three AOA sensors, then at least the electronics could have "voted" two-to-one which were correct and which "failed".

2: Whilst the stick-shaker seems to have been a warning there has been no mention (I may have missed it) of any particular flashing button, or message on a glass screen coming up to note that a particular AOA sensor had failed. I note that there will always be a problem with overloading pilots with information when there is an emergency but asking overloaded pilots to remember the possibility of a failed AOA sensor causing one-sided stick-shaker operation seems optimistic.

I haven't seen anything to suggest that the stick shaker activated on one side or another in this accident. We don't have that kind of detail on what went on, or I haven't seen it anyway. Boeing listed activation of stick shaker on one side as a possible symptom of this failure, in their list of other possible symptoms. Whether any one of the listed possible symptoms manifested itself on the accident flight is speculative at best.

This misconception has been floating around for long. The stick shaker is not an annunciation of a sensor failure.

It is the normal approach-to-stall warning triggered by a high AoA value. It does not know that that high AoA value is wrong, but for stall warning it is better to be safe than sorry, so the two stick shakers apparently are independent, and each each rely on the AoA probe on their respective side of the aircraft. Which makes perfect sense from a redundancy and failsale-design standpoint. If two AoA sensors disagree, don't try to be smart and figure out which might be wrong. Just activate a stick shaker on a high value. In most cases it is preferable to have a spurious stall warning when there is no stall, than not to have a stall warning on a real approach to stall.


TL;DR: A "failed sensor" did not activate the stick shaker. A high AoA value did.

Bernd