Indonesian aircraft missing off Jakarta
Join Date: Jul 2014
Location: Harbour Master Place
Posts: 662
Likes: 0
Received 0 Likes
on
0 Posts
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?
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?
Join Date: Jan 2017
Location: Canada
Posts: 1
Likes: 0
Received 0 Likes
on
0 Posts
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
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
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?
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?
There is no reference to the system in the Boeing FCOM. Therefore, there is no reference to it in any airlines operating manuals. The system will only drive the trim nose down.
Join Date: Jun 2002
Location: Slaving away in front of multiple LCDs, somewhere in the USA
Age: 69
Posts: 174
Likes: 0
Received 0 Likes
on
0 Posts
Join Date: Sep 2017
Location: Europe
Posts: 1,674
Likes: 0
Received 0 Likes
on
0 Posts
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.
That reasoning doesn't make sense, said Roger Cox, a retired investigator with the U.S. National Transportation Safety Board and a former airline pilot. Flight crews have a right to be concerned that details about the new system weren't included in manuals and the short training courses they were required to take before flying the upgraded 737, Cox said."I would be pretty pissed" about not being told, he said. "This is important systems information that pilots should know about."
Join Date: Mar 2014
Location: WA STATE
Age: 78
Posts: 0
Likes: 0
Received 0 Likes
on
0 Posts
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)
may be behind pay wall ...
By
Nov. 12, 2018 11:16 p.m. ET Boeing Co. BA -3.33% withheld information about potential hazards associated with a new flight-control feature suspected of playing a role in last month’s fatal Lion Air jet crash, according to safety experts involved in the investigation, as well as midlevel FAA officials and airline pilots.Andy Pasztor andAndrew Tangel
The automated stall-prevention system on Boeing 737 MAX 8 and MAX 9 models—intended to help cockpit crews avoid mistakenly raising a plane’s nose dangerously high—under unusual conditions can push it down unexpectedly and so strongly that flight crews can’t pull it back up. Such a scenario, Boeing told airlines in a world-wide safety bulletin roughly a week after the accident, can result in a steep dive or crash—even if pilots are manually flying the jetliner and don’t expect flight-control computers to kick in.
Join Date: Sep 2017
Location: Europe
Posts: 1,674
Likes: 0
Received 0 Likes
on
0 Posts
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)
may be behind pay wall ...
Power point rangers strike again- a few heads should roll in Commercial ---(IMHO)
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.
Join Date: Jun 2001
Location: UTC +8
Posts: 2,626
Likes: 0
Received 0 Likes
on
0 Posts
"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?
How about grabbing the trim wheel with your hand? Not part of MANUAL inputs?
Join Date: Apr 2014
Location: .za
Age: 61
Posts: 22
Likes: 0
Received 0 Likes
on
0 Posts
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.
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.
Join Date: Jun 2006
Location: Brisbane
Posts: 265
Likes: 0
Received 0 Likes
on
0 Posts
"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?
How about grabbing the trim wheel with your hand? Not part of MANUAL inputs?
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.
Join Date: Jun 2001
Location: Rockytop, Tennessee, USA
Posts: 5,898
Likes: 0
Received 1 Like
on
1 Post
https://www.wsj.com/articles/boeing-...ers-1542082575
Wall Street Journal article on the MAX flight control system.
Wall Street Journal article on the MAX flight control system.
Join Date: Sep 2017
Location: Europe
Posts: 1,674
Likes: 0
Received 0 Likes
on
0 Posts
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.
Join Date: Aug 2007
Location: London, New York, Paris, Moscow.
Posts: 3,632
Likes: 0
Received 0 Likes
on
0 Posts
Join Date: May 2006
Location: London
Age: 69
Posts: 237
Likes: 0
Received 0 Likes
on
0 Posts
.
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.
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.
Join Date: Feb 2000
Location: Alaska, PNG, etc.
Age: 60
Posts: 1,550
Likes: 0
Received 0 Likes
on
0 Posts
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.
Join Date: Jul 2007
Location: Germany
Posts: 556
Likes: 0
Received 0 Likes
on
0 Posts
[...] a single (?) AOA sensor failure [...] SEEMS to have activated the stick shaker
[...] there were two AOA sensors on the plane, so how did the FCS decide which one was at fault ?
[...] a failed AOA sensor causing one-sided stick-shaker operation seems optimistic.
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
