Go Back  PPRuNe Forums > Flight Deck Forums > Rumours & News
Reload this Page >

Ethiopian airliner down in Africa

Rumours & News Reporting Points that may affect our jobs or lives as professional pilots. Also, items that may be of interest to professional pilots.

Ethiopian airliner down in Africa

Old 7th Apr 2019, 11:11
  #3541 (permalink)  
 
Join Date: Apr 2005
Location: UK
Posts: 1,919
Originally Posted by GarageYears View Post
Why is it of note? This is normal STS action.

- GY
The STS functionality is also a software routine programmed into the FCC, it is a virtual system only.

The aviation community (outside of the test community) has become all-too-comfortable in accepting and using simplistic discrete 'system' descriptions for different functions that are actually hosted by a common system running a common code.

I readily accept and acknowledge that a number, or even the majority, of professional pilots will have their 'pedant' caption flashing when they read my words, but these distinctions matter. If and when Boeing produces an acceptable software-only fix for the current issues the only thing that will change will be the software version running in the FCCs.
Just This Once... is offline  
Old 7th Apr 2019, 11:23
  #3542 (permalink)  
 
Join Date: Jun 2006
Location: Brisbane
Posts: 23
Originally Posted by Just This Once... View Post
It is also of note that the FCC commanded the stab aircraft nose down 3 times with the flaps still set.
No, it isn't of note.

That's autopilot trim.

It is the autopilot keeping the aircraft in trim while it accelerates to the selected bug speed of 238 knots while engaged in LVL CHG mode. What would you have it do... fly out of trim?

(It isn't speed trim - if the pilot was flying manually, then speed trim would have activated, but it would have been nose up instead of nose down.)

If and when Boeing produces an acceptable software-only fix for the current issues the only thing that will change will be the software version running in the FCCs.
And your point is?

The current problem appears to be a poorly designed piece of software known as "MCAS".

The proposed solution is a better designed piece of software to replace it.

If it works, what are you getting agitated about?
Derfred is offline  
Old 7th Apr 2019, 11:26
  #3543 (permalink)  
 
Join Date: May 2016
Location: Nantes
Posts: 63
Originally Posted by AerocatS2A View Post

The AD does in fact say to trim the forces out before using the cutout. https://theaircurrent.com/wp-content...AX-AD-1107.pdf
As far as I understand english, it does not. It says electric trim CAN be used to neutralise column forces before cutout (nobody would think it cannot, anyway). It says also Manual trim can be used before and after cutout. It never say electric trim MUST be used to neutralise column forces before cutout
deltafox44 is offline  
Old 7th Apr 2019, 11:31
  #3544 (permalink)  
 
Join Date: Dec 2004
Location: Southern England
Posts: 109
Originally Posted by deltafox44 View Post
As far as I understand english, it does not. It says electric trim CAN be used to neutralise column forces before cutout (nobody would think it cannot, anyway). It says also Manual trim can be used before and after cutout. It never say electric trim MUST be used to neutralise column forces before cutout
Really?!!! You need that clarifying? Unbelievable.
Albino is offline  
Old 7th Apr 2019, 11:47
  #3545 (permalink)  
 
Join Date: Apr 2005
Location: UK
Posts: 1,919
Originally Posted by Derfred View Post
And your point is?

The current problem appears to be a poorly designed piece of software known as "MCAS".

The proposed solution is a better designed piece of software to replace it.
You are mistaken, there is no piece of software (or hardware known) as MCAS.

The software under scrutiny is for the Collins FCC / DFCS P11.1 and above.

If 'better' software is the accepted solution then the FCC / DFCS software will be the only thing revised.
Just This Once... is offline  
Old 7th Apr 2019, 11:55
  #3546 (permalink)  
 
Join Date: Jun 2006
Location: Brisbane
Posts: 23
For the non-pilots:

Boeing Quick Reference Handbook:

While every attempt is made to supply needed non-normal checklists, it is not possible to develop checklists for all conceivable situations.
In some multiple failure situations, the flight crew may need to combine the elements of more than one checklist. In all situations, the captain must assess the situation and use good judgement to determine the safest course of action.
The Flight Crew must be aware that checklists cannot be created for all conceivable situations and are not intended to replace good judgement. In some situations, at the Captain's discretion, deviation from a checklist can be needed.
Derfred is offline  
Old 7th Apr 2019, 11:59
  #3547 (permalink)  
 
Join Date: Jun 2006
Location: Brisbane
Posts: 23
Originally Posted by Just This Once... View Post
You are mistaken, there is no piece of software (or hardware known) as MCAS.

The software under scrutiny is for the Collins FCC / DFCS P11.1 and above.

If 'better' software is the accepted solution then the FCC / DFCS software will be the only thing revised.
And the portion of the software under scrutiny is referred to as MCAS. Yes, I get it, it all gets compiled into a software version and loaded into an FCC. So what? The offending bit is MCAS. The rest is fine.
Derfred is offline  
Old 7th Apr 2019, 12:02
  #3548 (permalink)  
Psychophysiological entity
 
Join Date: Jun 2001
Location: Tweet Rob_Benham Famous author. Well, slightly famous.
Age: 80
Posts: 4,856
Derfred #3586
The proposed solution is a better designed piece of software to replace it.
If it works, what are you getting agitated about?
Well, for my money, because it's still a quasi-sentient being that can still access the aircraft's controls.

The very least I would want is full annunciation of every input* . . . and the certain ability to stop it.
*Periodic movement of the Stab Trim wheel could be there anyway, so I would want a specific annunciation.


There's been little talk of MCAS putting settings back to where it found them before an input. I'm sure I read it, but is it true? If so, it seemingly failed to do so.
Loose rivets is online now  
Old 7th Apr 2019, 12:06
  #3549 (permalink)  
 
Join Date: Jan 2008
Location: Reading, UK
Posts: 11,593
Originally Posted by deltafox44 View Post
As far as I understand english, it does not. It says electric trim CAN be used to neutralise column forces before cutout (nobody would think it cannot, anyway). It says also Manual trim can be used before and after cutout. It never say electric trim MUST be used to neutralise column forces before cutout
There is nothing wrong with your understanding of English.
DaveReidUK is online now  
Old 7th Apr 2019, 12:20
  #3550 (permalink)  
 
Join Date: Apr 2008
Location: Paris
Age: 70
Posts: 275
Originally Posted by Derfred View Post


They can design a solid system, although never perfect. In this case, sadly, they failed to design a solid system. That is not in question. Even Boeing have effectively admitted this.

The question now is, “how and why did this happen?”, especially in such a tightly regulated, conservative and safety-conscious industry, with one of the world’s most respected organisations. The answer to that is now under extensive inquiry.

We may or may not ever discover the truth, but typically when this many people die unnecessarily, the difficult questions finally get asked, and those with the answers are forced to actually answer.

Of course, it will fundamentally point to one thing: MONEY.

But we aren’t going to get rid of money, so it’s the movement of money, to whom and how much, and how much those in charge of money get to influence those in charge of solid design, that will come into question.




Well, if by operator, you mean the airline, well they are in charge of employing sufficiently skilled pilots and providing them sufficient training to get their passengers from A to B safely. The airline is also in charge of purchasing sufficiently safe equipment to do so, and maintain it to a sufficient standard.

If they fail to do this, they must accept some liability for the failure. Whether they failed to do this is not yet ascertained - some think the pilots should have saved the passengers from the design fault, some think that’s an unreasonable ask, and some think it was impossible.


If, on the other hand, by “operator” you mean the particular pilots involved, well, in my opinion, pilots have a personal obligation to maintain a standard on top of that required by their employer and their regulator. They can also be held personally liable for the failure, and depending on the global jurisdiction may be supported and/or indemnified by their employer, or, not.

Aviation safety is a rich tapestry, that normally results in a high level of safety, but many argue that it is gradually being eroded in standards of design, training, and skills, generally by one thing: MONEY.

Think about that next time you buy the cheapest ticket available, because that MONEY only comes from one place: you. The less you pay, the less MONEY available to pay someone to design a solid system, or to pay or train the pilot to save you from the less-than-solid system.
Absent regulation, any money that goes into the system just goes to management and shareholders. the Boeing 737 Max 8 failure has little to do with pilot training, or with not enough money for safety, it was caused by Boeing figuring out a way around the process of verifying the design. They could afford to lose a month or two and go through the process, and indeed they can afford it now.

Edmund
edmundronald is offline  
Old 7th Apr 2019, 12:29
  #3551 (permalink)  
 
Join Date: Dec 2015
Location: Cape Town, ZA
Age: 58
Posts: 424
FullWings Thanks for your insightful comments.

In the case we are discussing, an AoA probe failure (which is singular, predictable and measurable) has caused a cascade of issues and warnings that are difficult to assimilate and don’t immediately point to any particular checklist
Your statement reinforces a point I made earlier. We have vividly seen how faulty AOA data on the B737 affects so many systems simultaneously, that it creates a hazard in itself.

IMO AOA disagree should never have been an optional display extra, but instead trigger a high priority checklist on its own. BTW, a false low AOA value would not trigger a stick shaker, but does comprise a degraded flight condition.

The proposed software fix will remove the possibility of catastrophic MCAS activation. However the potential for a cascade of AOA derived warnings remains on the B737, including the wider NG series, and should be a concern.

Prompt identification of the underlying AOA trigger would avoid going down multiple redundant fault trees. I understand that changing existing checklists should not be treated lightly, but IMO the current review should be an opportunity to enhance this process.

Edit: Derfred Thanks for the note about discretion to bypass checklist rules.

Last edited by GordonR_Cape; 7th Apr 2019 at 12:42.
GordonR_Cape is offline  
Old 7th Apr 2019, 12:32
  #3552 (permalink)  
 
Join Date: Jan 2004
Location: Here and there
Posts: 2,842
Originally Posted by deltafox44 View Post
As far as I understand english, it does not. It says electric trim CAN be used to neutralise column forces before cutout (nobody would think it cannot, anyway). It says also Manual trim can be used before and after cutout. It never say electric trim MUST be used to neutralise column forces before cutout
Yes, it doesn’t say “must”. It also doesn’t say “must not”. Given that there is a reminder there that it CAN be used prior to cutout, what would be the reason for NOT using it to fully counter the MCAS? Aside from the design failures themselves, a key to this accident is why weren’t they trimming up as far as they needed to? I know it’s been asked numerous times already in this thread, but it is perplexing.

BTW, it does say at the very start of the trim runaway (in the AD not the abbreviated memory item procedure) to disconnect the autopilot and control pitch with column and electric trim. That’s not a “may” or “can”.
AerocatS2A is offline  
Old 7th Apr 2019, 12:33
  #3553 (permalink)  
 
Join Date: Jun 2008
Location: London
Age: 64
Posts: 316
Well, if by operator, you mean the airline, well they are in charge of employing sufficiently skilled pilots and providing them sufficient training to get their passengers from A to B safely. The airline is also in charge of purchasing sufficiently safe equipment to do so, and maintain it to a sufficient standard.

If they fail to do this, they must accept some liability for the failure. Whether they failed to do this is not yet ascertained...
I think it would be somewhat unlikely for liability to be attributed to Ethiopian Airlines for failing to doubt the safety of a brand new aircraft from a major manufacturer that had been certified as safe by the regulator. To my mind, operators buying aircraft are entited to rely on the assurances of a competent authority that design and manufacture complies fully with the standards that have been laid down. This is the fundamental principle behind the certification process - the standards are there to ensure safety, and purchasers should therefore be confident that the equipment satisfies their duty of care to pax and crew in this regard.

As for training, how are you supposed to train, or direct training, for a system on which you have little or no information? If an airline ensures that its pilots complete the training recommended by the manufacturer and approved by the regulator, it would be very hard to prove at a later date it should have guessed that more needed to be done.

QUOTE] If, on the other hand, by “operator” you mean the particular pilots involved, well, in my opinion, pilots have a personal obligation to maintain a standard on top of that required by their employer and their regulator. [/QUOTE]

A laudable view but hard to achieve in practice. Regardless of the operation (fixed wing, rotary, commercial, non-commercial etc) there will be those who achieve and maintain a higher standard than that required simply because they are gifted as pilots, whereas others will have to work much harder. That said, I agree with the point about money/investment - it is next to impossible for pilots to voluntarily improve skills when the tools do the job are unavailable because of policies on hand-flying v automation and the absence of resources for non-jeopardy sims.

It is going to take multiple lines of specialist investigation to bottom all this out. In 3500+ posts on the thread, we still have arguments raging about what this crew should have done (with hindsight...), how MCAS works and why it was implemented, what the implications are for managing the trim system, where the design may have failed, the roles of Boeing and the FAA in the certification process, what should happen with training, and of course the inevitable PPRuNe sport of playing the man rather than the ball. We have had some very thoughtful and helpful interventions and some frankly unhelpful diversions

For the purposes of further meaningful discussion, I think it would be very useful if someone could collate the most valid information on MCAS and the MAX trim system and have it posted on a separate locked thread that the rest of us can use for reference. That way, some of the excellent grains of truth in this very lengthy thread would not be lost/forgotten, and we would not have to keep going round the same buoys time after time.
Fortissimo is offline  
Old 7th Apr 2019, 12:57
  #3554 (permalink)  
 
Join Date: Jan 2010
Location: UK
Posts: 143
Originally Posted by Albino View Post
Spot on, it's is also the view of every colleague I have spoken to.
It seems clear from the posts of various experienced 737 pilots that both sets of pilots messed up, didn't follow clear NNCs and are therefore solely and exclusively responsible for tarring Boeing's reputation and causing such unnecessary alarm that the 737 MAX was grounded. Obviously this would never have happened with US, European or Australian pilots who would have done the right thing. Since it's clear that there is nothing that Boeing can do to bring pilots from Asia and Africa up to the afore mentioned standards the solution is obvious. Just don't sell Boeings to Asia and Africa with perhaps the odd exception for Japan and Singapore. Job done!

What's that you say? Boeing says they have a problem with that because they won't make a big enough profit and that would leave the field open to Airbus? Surely that would just mean Airbus aircraft crashing with the consequent deep smelly stuff and no skin off Boeing nose? Still not good enough? Well I suppose Boeing will just have to change their assumptions about what pilots will and won't do and then design their aircraft and associated documentation so pilots from all continents will follow the correct action(s) and not crash their Boeing aircraft. After Boeing's a business and a key purpose of business is to make money.

N.B. In case you haven't twigged it yet I very much do not repeat not hold the views expressed in the first two sentences.

Last edited by SamYeager; 7th Apr 2019 at 13:01. Reason: Typos
SamYeager is offline  
Old 7th Apr 2019, 13:56
  #3555 (permalink)  
 
Join Date: Jul 1998
Location: Northern Europe
Posts: 42
Originally Posted by FullWings View Post
Very much in agreement.

The Human Factors are, IMO, the most important/interesting part of these accidents.

To recap: There are many situations which require some sort of action from pilots, be it promptly or after consideration. The more time-critical an event is, the less time/capacity there is to figure out what to do, so responses to predictable events are based more on rules than extended cognition, hence “memory” or “recall” items are used. They need to have a simple, unambiguous trigger, e.g. an engine fails below V1, perform an RTO or GPWS says “PULL UP!”, perform the GPWS pull up manoeuvre.

When the situation is more complex and there is normally time for diagnosis, we have reference checklists which may contain decision trees, often leading to different actions and outcomes, dependent on further data. If no checklist really fits the bill completely, maybe due to multiple failures or unusual circumstances, then you need to use your general aviation understanding, backed up by specific type knowledge and all the resources you have access to in order to formulate and execute a plan of action. This is something you would generally do *after* you had determined there were no published normal or non-normal produces that were applicable, or you had applied the procedures and they had not helped or made the situation worse. Boeing specifically caution against “troubleshooting” unless all other possibilities have been exhausted but they also provide a useful “Situations Beyond the Scope of Non-Normal Checklists” guide in their training manuals.

Now, it is good aviation practice to have some kind of action associated with a single, predictable failure which affects the safe operation of the airframe, be it recall items or a reference checklist, or even just a note for crew awareness. In the case we are discussing, an AoA probe failure (which is singular, predictable and measurable) has caused a cascade of issues and warnings that are difficult to assimilate and don’t immediately point to any particular checklist, except maybe the Airspeed Unreliable one, which doesn’t include deactivating the trim. Remember we are looking at these accidents with hindsight and the warnings that occurred can be triggered by many different events that require different responses - we only know which was the correct path to take because we have most of the data in front of us to peruse at leisure.

There have been quite a few posts highlighting the startle effect plus the saturation of input channels by excess information of questionable usefulness, e.g. stick shaker, GPWS, fault messages, high control loadings, etc. It is quite easy to see how some things were missed, in fact most of the above is taught in basic HF modules but this seems have passed some manufacturers by.

It’s easy to say that you’d have disconnected the trim as soon as you got a stick shake in the climb out because the flaps are correct and power is set. Well done. But supposing that was a *real* stall warning because you put the wrong weights in the FMC so have rotated 20kts early? Not so well done now, eh? This has happened before and will happen again and is just one example of why it is so important NOT to rush to conclusions if you can absolutely help it.
Hi FullWings.

Your explanation on how things are resolved in a modern day cockpit makes for a very interesting read and should be part of the curriculum for any up and coming MCC/JOC student. It should also be interesting for the laypeople frequenting these pages. For a professional airline pilot it should be obvious.

I agree with you that Human Factors is a subject of much interest and it is also where I feel I still have the most to learn about the Ethiopean accident. As much as I hate this MAX software addition and its capabilities, I do think I have picked up on the significant features of the MCAS and further detail on it would most likely not have had any influence on how I would deal with an "MCAS Runaway Stabilizer" or whatever we end up calling this scenario.
Although some contributors on this forum have a less than diplomatic way of stating certain facts and assumptions about the crew's actions and inactions I don't think this should be interpreted as putting the whole blame on the crew. Not even close. But there certainly is a lot to be explored following the statement by Ethiopean officials that the crew "followed expected procedures" implying there are no issues whatsover concerning the crew's way of dealing with the problems of this flight. And it is in this space I believe some posters in here get a little bit agitated, trying to get that point across.

There certainly were a number of crossroads at which catastrophy could have been avoided on ET302, especially up to the point of flap retraction and a bit, and from a Human Factors perspective it is extremely interesting to learn why certain choices were made. We all know that the company culture of an airline and also the culture of countries/regions greatly influence how we behave, both as people and as pilots. This has nothing to do with the "supremancy of the Western pilot" or however some may want to phrase it in these times of identity politics.

But when countries ban unions, when people are fired for having opposing views to those of their superiors, when airlines ban handflying within the autopilot envelope and mandate autolands, when airlines have the captain always be the Pilot Flying, when one thousand airline flying hours may entail only a dozen or two actual take-offs and landings.... If you become financially penalized or limited in your career advancement due to non-compliance with said policies, you know there are issues that need to be addressed. I don't think it should be perceived as offensive to ask if any of these or other factors were important when it comes to understanding why a seemingly experienced captain would try to engage the autopilot at 400'AGL while the stickshaker is going off? And why choose the onside autopilot? Why clean up? Regardless of any NNC memory/recall items or checklists, why not establish a known and safe pitch/thrust setting and fly the aircraft? Does everything boil down to "the startle effect" when at first the stick shaker goes off and then later the AP trips off at the same time they clean up? These are not unreasonable questions to ask.

It is a sad fact that whoever is left holding the matches when the house burns down will be looked at with much scrutiny - even by his friends.
TTail is offline  
Old 7th Apr 2019, 14:03
  #3556 (permalink)  
 
Join Date: May 2008
Location: El Paso, Texas
Age: 69
Posts: 28
Originally Posted by Fortissimo View Post
I think it would be somewhat unlikely for liability to be attributed to Ethiopian Airlines for failing to doubt the safety of a brand new aircraft from a major manufacturer that had been certified as safe by the regulator. To my mind, operators buying aircraft are entited to rely on the assurances of a competent authority that design and manufacture complies fully with the standards that have been laid down. This is the fundamental principle behind the certification process - the standards are there to ensure safety, and purchasers should therefore be confident that the equipment satisfies their duty of care to pax and crew in this regard.


QUOTE] If, on the other hand, by “operator” you mean the particular pilots involved, well, in my opinion, pilots have a personal obligation to maintain a standard on top of that required by their employer and their regulator.
A laudable view but hard to achieve in practice. Regardless of the operation (fixed wing, rotary, commercial, non-commercial etc) there will be those who achieve and maintain a higher standard than that required simply because they are gifted as pilots, whereas others will have to work much harder. That said, I agree with the point about money/investment - it is next to impossible for pilots to voluntarily improve skills when the tools do the job are unavailable because of policies on hand-flying v automation and the absence of resources for non-jeopardy sims.[/QUOTE]

The good news for aviation safety is that these two accidents have shown a bright lite on aircraft design and certification. The liability question can be answered at this point. Regardless of how poor the skills ,training or supervision of the crews might be proven to be, the aircraft design led directly to the accidents. The fact that a well trained crew on Monday morning, could possibly have recovered the aircraft successfully, will not be relevant in shifting the major liability.

As far as the future of the 737 Max, hopefully Boeing will be required to do enough recertification to prove that no automated system can put the aircraft in an unrecoverable configuration, in other words, that the manual stab trim wheel can reasonably be used even at high speed, high g load and high elevator forces. Also they will need to find a simple way of allowing the crew to quickly analyse compounding failures.

in reviewing the performance of the crew, it cannot be over emphasized how disorienting multiple failure manifestations can be. If a crew does not fight an aggressive mental battle, fixation occurs quickly. For example, real stick shaker is rarely encountered. When it is, you are usually aware that you are approaching a limit anyway, perhaps slowing and near a flap extension speed and you hit some turbulence that gives you a momentary stick shaker. This is not alarming. But if you do not have a clue why you have a stick shaker, it is very distracting. In olden times the only way to get rid of it was to find the CB. Then you add other stall warning lights and sounds, if there is no way to rapidly get rid of erroneous warnings they take a toll on your mental state. A Navy flight instructor once told me that the first step in any emergency procedure was, "wind the clock." I don't think he was serious but the point is to maintain initiative. First due no harm. Do common sense things. Silence unneeded sound and get rid of warnings. Then confirm situational awareness. Altitude, terrain, speed, attitude, power setting, configuration, standby instruments. Make appropriate corrections, if not stable, get stable. This process, for an experienced pilot takes seconds.
abdunbar is offline  
Old 7th Apr 2019, 14:36
  #3557 (permalink)  
 
Join Date: Dec 2018
Location: 8th floor
Posts: 0
It's interesting that the Lion Air crew on the flight before the accident also raised the flaps while having unreliable airspeed and the stick shaker. So 3 out of 3 of the crews experiencing the failed AOA sensor did this.

Looking at the FDR traces for the previous Lion Air flight, one difference is that they also enabled the A/P, on the F/O side, when they retracted the flaps. The Ethiopian crew enabled A/P on the captain's side, and started retracting the flaps about 20 seconds later.

In both cases, MCAS activated after the A/P deactivated. For the previous Lion Air flight the fight with MCAS lasted over 4 minutes before they used the cutout switches. For the Ethiopian flight it lasted only 30 seconds.

Another difference for the Lion Air crew that saved the aircraft is that they did the unreliable air speed checklist, according to the preliminary report. And while we can't determine from the FDR trace of the previous Lion Air flight what their exact speeds were, it probably resulted in a more manageable speed.

Both crews later re-enabled electric trim (the Lion Air crew temporarily). And there is nothing in the runaway stabilizer memory items explicitly saying you should not re-enable electric trim. It does however explicitly say that for the autopilot and autothrottle: "Do not​ re-engage the autopilot.​" "Do not​ re-engage the autothrottle".

And, from the FDR traces, the Lion Air crew that saved the aircraft also didn't bring the aircraft to neutral trim before using the cutout switches. And later they did just what the Ethiopian crew did seconds before the crash: they re-enabled electric trim, they started trimming ANU, and MCAS started trimming AND again. Then they used the cutout switches again to stop the runway, again without bringing the aircraft to neutral trim with the thumb switches first. Then they trimmed with the trim wheels for the remainder of the flight.

I can't help but wonder if their knowledge about MCAS is what contributed significantly to the Ethiopian accident, by making them prioritize the stabilizer runaway memory items over everything else, making them tunnel vision and focus on the trim problems primarily, and ignoring other issues, like the increasing speed, and the need to perform other checklists.
MemberBerry is offline  
Old 7th Apr 2019, 14:51
  #3558 (permalink)  
 
Join Date: Dec 2004
Location: Southern England
Posts: 109
Originally Posted by SamYeager View Post
It seems clear from the posts of various experienced 737 pilots that both sets of pilots messed up, didn't follow clear NNCs and are therefore solely and exclusively responsible for tarring Boeing's reputation and causing such unnecessary alarm that the 737 MAX was grounded.
I disagree....

Boeing ARE responsible for a poorly designed system, I've yet to meet anyone who doesn't feel the MCAS should not have been certified, allowed to work from a single sensor or able to make the level of input that it does.

Where the difference of opinion lies is that Boeing are solely responsible, particularly for the Ethiopian crash. Their press release stated that all procedures were followed and press around the world are stating as fact that this was completely the fault of the aircraft.

Looking at the information released it is hard to agree. Procedures were not followed. Control of the aircraft was not maintained. The crew had direct control over the stabilizer (apart from when the cutouts were used) at all times. Flying the aircraft is the most basic aspect of our job and the most important.

My final post on this topic.
Albino is offline  
Old 7th Apr 2019, 16:14
  #3559 (permalink)  
 
Join Date: Apr 2019
Location: Michigan
Posts: 4
Following this thread and others on other forums I've seen the reason for MCAS explained and occasionally debated and I'm left with a question about the decision making that determined that software that controlled the trim was the best way to manipulate stick feel.

My understanding is that MCAS applies AND in order to comply with the regulation requirement that says that the stick pressure must feel a certain way as the aircraft's nose pitches upwards. If it's only the "feel" of flying the aircraft that needs to be changed why not write software that applies forces to the controls themselves instead of applying sporadic input to one of the main pieces that keeps the plane balanced in flight?
shmerik is offline  
Old 7th Apr 2019, 16:15
  #3560 (permalink)  
 
Join Date: Aug 2013
Location: Washington.
Age: 70
Posts: 523
Originally Posted by Albino View Post
I disagree....

Boeing ARE responsible for a poorly designed system, I've yet to meet anyone who doesn't feel the MCAS should not have been certified, allowed to work from a single sensor or able to make the level of input that it does.

Where the difference of opinion lies is that Boeing are solely responsible, particularly for the Ethiopian crash. Their press release stated that all procedures were followed and press around the world are stating as fact that this was completely the fault of the aircraft.

Looking at the information released it is hard to agree. Procedures were not followed. Control of the aircraft was not maintained. The crew had direct control over the stabilizer (apart from when the cutouts were used) at all times. Flying the aircraft is the most basic aspect of our job and the most important.

My final post on this topic.
The primary problem is the design. PERIOD
It’s fine when things are normal, deadly when they are not. It was not designed for fault tolerance. If AOA inputs are invalid, perhaps with IAS disagree, the initial procedures (pitch & power), coupled with unwanted nose down trim will naturally lead pilots to maintain proper pitch, speed increases, MCAS trim down more and on and on. Pilots hit Trim Cutout and are left with manual (slow) trim which becomes increasingly difficult to use as speed increases, until it becomes impossible. Can’t unload (nose down) at 1000 feet, and there’s too much nose down trim to control the airplane.



GlobalNav is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.