Ethiopian airliner down in Africa

[Lord Farringdon]

Originally Posted by wonkazoo

Someone else has properly offered here that the ET incident may well be traced at it's most basic human factors core to the impairment the pilots experienced due to the previous Lion Air crash. In other words: Their consciousness knew how the last one went down, so their bodies responded accordingly, which left them poorly equipped to actually perform the steps you have been seemingly demanding that they do since shortly after they in fact died.

Regards-
dce

FWIW from and ex non-pilot military aircrew viewpoint, I have been in a few crappy situations when the day has just gone bad. In mil ops we operated close to the envelope in unfamiliar environments and it's the nature of these ops that means that sometimes, on thankfully very rare occasions, guys didn't come home. We all read the accident reports and make mental notes to ourselves...must be wary of that...must not do that ...must make sure I communicate that better...take another look at that checklist etc etc. But when it happens, the engine fire, the stuck main landing gear, the assymetric flap, the loss of hydraulics, smoke and fume, lightening strikes, severe CAT in the middle of an otherwise smooth moonlit cruise, flapless over the fence on short runway at 160 kts etc etc, there is a startle factor, there is time when you hear nothing and see nothing or can't make sense of anything, there is puzzlement and a fear that your event could well be the subject of the next accident report, and yes, a not unnatural fear that this could be your last flight. There is no immediate recall capacity because your senses are so overwhelmed with incoming information that you just can't assemble any course of action except whats right in your face and that leads to target fixation, like trying to control and uncontrollable wildly spinning aircraft, like trying to select the autopilot on, again and again and again!. It takes a few moments, but eventually, the haze clears. The airplane is still flying, (not in Wonkazoos case) new information is not coming and it seems like time has slowed down. Things start switching back on, you start to interpret the sounds you are hearing, the things you can see and thankfully, you start to recall memory actions. In Wonkazoos case the information didn't stop coming. Excessive and continuous G force is an overwhelming inhibitor to clear thinking. But fortunately he broke the target fixation and bailed. Everyone who has experienced hypoxia training will have experienced target fixation and how difficult it is to self recognise it let alone break it. Unlike Wonkazoos rather more desperate situation, my personal experiences were the type of things you might train for in a simulator. So much so that once you are over the startle and the haze, the immediate actions are almost routine. Importantly, you burst into pre-trained action safe in the knowledge that the event didn't kill you, that the bird still has its feathers and is flying and that if everyone does exactly as they are trained to do we'll get this thing on the ground even if the aircraft may not be reusable afterwards!

Wonkazoo and 737 Drivers' positions are so far apart but can easily be explained by the entirely different nature of events these guys have experienced and/or trained for. My experiences would lead me to agree with 737 Drivers view. That is, you get a scare, the event stabilises, you shake yourself off and go to memory recall. All going well, you, rather than someone else gets to write the event report afterwards. But now we come to ET. This should have been non-threatening 'routine' emergency. I know, using 'routine' and 'emergency' together is an oxymoron but you are trained for this right? That's why we are checked to fly. We are supposed to know what to do in these circumstances in the air because for all those recall items we maintain 100 percent recall training for them on the ground. The ET Captain would have been living under a rock and the airline grossly negligent if he wasn't aware of the Lion Air accident and what Boeing subsequently directed was his best and only courses of action to avoid disaster.

So why didn't he handled it correctly? Why didn't he just manage the UAS, turn back and land? My belief is that he didn't feel he was experiencing a routine UAS, or shall we call this a 737 Driver type of emergency, but rather that this nasty MCAS beast, that he only relatively recently become aware of, presaged by a UAS event had selected him that day. I believe there was too much information coming in for him to get out of startle mode and that this was aggravated by an early immediate assessment that he was in a fight for survival with MCAS right from the get go. He was thinking too far down track, to something that hadn't even happened yet but which led to target fixation on selecting auto pilot and his subsequent cognitive inability to deal with flaps, Vmo or cutout switches. He was not experiencing a 737 Driver "do the checklist your trained for" type of emergency but rather the "Oh no, not this" or Wonkazoo type of emergency where a fight to the death was about to start.

If the ET Captain had never heard of MCAS, he probably would have carried out the UAS and landed safely. Basically, his mere knowledge of MCAS but lack of full understanding of it may have scared the c##p out of him. How many reports have their since been of pilots that wont fly the airplane again until they are satisfied Boeing's fix and training solutions are 100 percent and in some cases others saying they just wont fly it again regardless. The ET Captain would have been deeply concerned about the possibility of a MCAS event and this self - fulfilling prophecy may have led him into the clutches of MCAS from which there was no escape.

Watch this scene from "Glory".

You Tube

and identify the difference between the 737 Driver correct actions and satisfactory outcomes and the Wonkazoo actions and outcomes. The soldier considers himself a pretty good shot but it doesn't take much to imagine the Colonel as MCAS and the soldier as the ET Captain. You see the soldier startle, you see his fumbling attempts to do a simple task, that previously he had done with aplomb and you see the utter disbelief at the outcome.

So sorry for the long opinionated post but I hope it provoked some thought. 737 Driver and Wonkazoo had an interesting, lively and ultimately respectful discussion some posts back from which I learnt a lot. I think ultimately they are both right..but for different reasons.

[PaxBritannica]

There's no date on that Boeing statement. Was it issued before or after the Ethiopian crash?

In 2017, within several months after beginning 737 MAX deliveries, engineers at Boeing identified that the 737 MAX display system software did not correctly meet the AOA Disagree alert requirements

.

I believe they started delivering the MAX in May 2017?

Accordingly, the review concluded, the existing functionality was acceptable until the alert and the indicator could be delinked in the next planned display system software update.

How long does that process take? By October 2018, nothing had happened. Boeing have been vague about exactly when the discrepancy was noticed, so let's say they had seventeen months to get the software fix designed and installed. Is seventeen months the standard kind of time it takes for aviation software fixes to get implemented? (And there's not much evidence the fix was even under design, prior to Lion Air.)

Everything I've read suggests a major schism between the engineering layers at Boeing and the commercial execs, with all the power in the hands of the execs. So I'm not surprised to read:

Senior company leadership was not involved in the review and first became aware of this issue in the aftermath of the Lion Air accident.

[ATC Watcher]

Lord Farringdon thank you for posting that video. very enlightening , and conform to what I personally witnessed and experienced during an aviation accident a few yeas ago. Like you I do not consider Wonkazoo and 737 Drivers' positions to be opposite, but rather complementary to one another. Very good to have both of them here .

Pax Britanica :

Senior company leadership was not involved in the review and first became aware of this issue in the aftermath of the Lion Air accident.

This looks to me as been a sentence dictated by lawyers rather than a fact, but I am sure that if it is not true we will see copies of emails surfacing in the Seattle Times or Wall Street Journal pretty soon ...

[PaxBritannica]

Originally Posted by ATC Watcher

.

Pax Britanica :

This looks to me as been a sentence dictated by lawyers rather than a fact, but I am sure that if it is not true we will see copies of emails surfacing in the Seattle Times or Wall Street Journal pretty soon ...

Note the other distancing strategy:

The software delivered to Boeing linked the AOA Disagree alert to the AOA indicator, which is an optional feature on the MAX and the NG. Accordingly, the software activated the AOA Disagree alert only if an airline opted for the AOA indicator.

This suggests some contractor somewhere is being lined up to shoulder the blame, or at least allow Boeing to reduce their exposure.

We're expected to believe that Boeing specified the feature correctly, but did not assess the software that got returned, or test it exhaustively? Did the contractor also get to self-certify?

[groundbum]

Senior company leadership was not involved in the review and first became aware of this issue in the aftermath of the Lion Air accident.

This is the sound of low level engineers being thrown under the wheels of the bus.

The question should be asked; in a safety first company how come the leadership didn't hear? There should have been a well established high priority channel within the company where safety issues could not be ignored or neglected or hushed up. If they want the flying public's confidence, and even more important the pilots confidence in their products, they need to rectify this see no evil hear no evil culture they've created.

G

[737 Driver]

Originally Posted by fdr

737D;

your posts indicate that the crew of the flights were less than competent in essence, however, you also suggest that the training standards are deficient. One specific on competency is your statement that you would respond in the event that these crews encountered by recognising the problem, identifying the cause and completing the action within "5 seconds".

If I recall correctly, the "5 second" remark was specifically in reference to a certain set of steps on the runaway stab trim checklist. Apparently there is a "demo" video on YouTube that gives the impression that it takes longer, and someone was under the impression that this length of time was one of the things working against the crew. I was simply pointing out that it could have been done quicker. In another post, however, I also pointed out that the crew could take all the time they needed to get the aircraft back to neutral trim as long as one of the pilots was, yes, FLYING THE AIRCRAFT and managing the trim using the yoke switch.

I agree that training needs to be lifted around the industry, we don't necessarily need more training, we need training that is not wasteful fo the resources that exist, as they are to day. We are currently governed by the aviation industries own version of political correctness, A.K.A. as SMS, and QA. In order to give a simplified box ticking exercise to regulators and managers, we come up with matrices and checklists that are fantastic for showing compliance, but, that is all. There is no closure of the loop on the fact that the crew may comply with a procedure or policy that in itself increases operational risk, or is impossible to do as it conflicts with the real world. The other sort of failure (think false negatives, false positives) arise when the boxes get ticked, but the impact of implementation is not observed. Our roles, policies and procedures are developed usually as bandaids on top of bandaids to reduce the risks of something, either real risk, or showing compliance (another form of risk - commercial). In all cases, however it is unlikely that the 200 hr pilot sitting in the RHS seat of the plane was the cause of the competency issues, he/she cannot be other than the logical outcome of what the industry has accepted as a good solution to unfettered growth (a cancer in effect, sounds good until the consequences start being felt).

I fully agree with this.

​​​​​​A final thought: The crews encountered an unusual trim case, the checklist is for a runaway trim, yet the problem did not actually present as such, there was a trim error that occurred, but the trim responded normally to the crews trim inputs, and then after a period of time was anomalous again. That is not a simple set of facts to decipher in short order. Given their time over, I expect that the crew would follow your advice and act within 5 seconds and cure the ills of the world.

Again, I think you are reading to much into that "5 second" comment. I agree that, at least to the Lion Air crew, this presented itself as a novel malfunction. There has been some questions raised about how clearly the post-Lion Air AD and related information was transmitted to the Ethiopian flight crews. However, I will also point out that in the history of aviation, there will always be someone who gets to experience a malfunction for the first time. That is why I keep harping on the mantra (I think you know it by now )

The mantra assumes that a flight crew may be presented with a novel situation that will require time to sort out. And I will say again, if either of the accident crews had done nothing but apply the mantra, particularly the "Trim the Aircraft" part, they would have bought themselves sufficient time - basically until fuel exhaustion - to figure out what was going on. That is way more than 5 seconds.

[NutLoose]

Sadly it seems to follow this example as to why

https://news.ycombinator.com/item?id=19389983

[737 Driver]

Originally Posted by Mach2point7

The "Boeing Statement on AOA Disagree Alert" tells us that the MAX has had an AoA disagree alert function from the outset, but in error, it was not displaying to the aircrew. There is a long and convoluted explanation/justification of why that deficiency may not have been critical.

The Boeing spokesperson is essentially correct. Again, I am not defending the overall sloppiness that this particular piece displays, and it is just another example in a growing list of how the MAX development program wasn't managed within the high standards that are normally expected of an aircraft manufacturer.

Strictly from a technical perspective, however, it needs to be pointed out that if a 737 crew were to receive an "AOA Disagree" message and go to the appropriate NNC, that checklist would simply direct them to the "IAS Disagree" checklist and/or the "ALT Disagree" checklist as appropriate. The "IAS Disagree" checklist would then direct the crew to the "Airspeed Unreliable" checklist, which has already been discussed extensively. In short, if the AOA disagreement becomes significant enough to impact the flight instruments or other systems, there will be plenty of other indicators for that problem (stick shaker, "IAS Disagree" alert) and so the "AOA Disagree" message is somewhat redundant in terms of directing the crew to the proper procedure.

The real issue is that if the AoA disagree signal system was available " in keeping with Boeing’s fundamental design philosophy of retaining commonality with the 737NG" why on earth was it not used as a critical input to the MCAS activation logic ??

Very good point, and I believe the MCAS update will do exactly this. I suppose the answer to why this wasn't done in the first place resides in the thinking that led to the MCAS design team using only one AOA input. This probably arose from the fact that the MCAS is considered to be an ancillary function of the Speed Trim System (STS). The STS has been around since the 737NG was launched and it has always relied on just one AOA input. The difference is that the STS respects the control column trim cutout switches (this is different than the pedestal cutout switches) and MCAS does not. The control column cutout switches prevent the STS from trimming nose down when the control column is moved aft. Apparently no one connected the dots that by removing the control column cutout switches from the circuit, MCAS was now set up to malfunction in a novel and hazardous manner.

[MurphyWasRight]

On UAS:

Originally Posted by 737 Driver

Unfortunately, our company manuals don't go into that level of detail. It does have this little gem, though: "If the flight crew is aware of the problem, flight without the benefit of valid airspeed information can be safely conducted and should present little difficulty." Just a walk through the park.
.

Does it include "land at nearest suitable airport".?
The Lion Air prelim report on the penultimate flight crew:

The pilot performed three Non-Normal Checklists (NNCs) consisting of Airspeed Unreliable, ALT DISAGREE, and Runaway Stabilizer. None of the NNCs performed contained the instruction “Plan to land at the nearest suitable airport”.

Seems to me with that much 'stuff hitting the fan' (polite form of a well known technical term) I think that pressing on was a bit of a gamble, that they did probably may relate to commercial pressure.
Interest to know what % of commercial pilots reading this would have pressed on.

737 driver

Reference deactivated "AOA Disagree" alert.
Sloppy, sloppy, sloppy.
That being said, I think it is fair to say that prior to the MAX accidents, most of the pilots at my airline had no clue that there was such a thing as an "AOA Disagree" alert. I'm not sure it would have made any difference.

Could have made a big difference in Lion Air if the penultimate crew had included it in the tech log. I say if because they seem to have left out using trim cutout.
ET might have been the first one in that case,

[cavuman1]

Here is a link to a Wall Street Journal article which claims that Boeing had withheld information about MCAS for more than a year before the Ethiopian accident: BOEING WITHHELD MCAS SAFETY INFORMATION

- Ed

[737 Driver]

Originally Posted by Rx7man

On the subject of training, what I find quite unbelievable is that every airline seems to have their own training procedures for a specific aircraft... Shouldn't there be just standard training dictated by the manufacturer of the aircraft and that should cover everything required.. there should be no need for carrier specific training other than perhaps some company policies, but nothing related to operating the equipment.

I do not disagree in theory, but IMHO, the reality is that the training standards dictated by Boeing have been catering to the lowest common denominator for years. They have a strong incentive to sell aircraft across the entire spectrum of airlines and countries regardless of the depth and quality of their aviation heritage. Requiring a higher level of demonstrated skills for the operator potentially translates into higher costs and lost sales.

Sadly, this thought process does not stop at Boeing. I recently had an opportunity to fly with FO who was relatively new to the 737. During our trip, we discussed a number of issues that had come out of the recent MAX crashes. During this conversation, he confessed that before these accidents, he did not even know the stab trim wheel had a stowable handle and had never been trained in its use. Think about that for a moment. Also consider that a freshly-minted 737 Captain would have received the exact same training.

After I picked my jaw up off the floor, I proceeded to personally give the FO the training he had missed. Afterwords, I shared my concerns with my Fleet Manager and told him in no uncertain terms that our training programs needed a thorough review. The Fleet Manager replied that this was already in progress, and stated that our training programs were constantly being reviewed for improvement. He added a telling remark, however, that stab trim malfunctions had never been a statistically significant problem at our airline, implying of course that the training events our pilots are exposed to constantly needed to be justified by historical data. I told him that if the MAX accident had occurred at our airline, the family of those who perished would have been rightfully angered if it had come to be known that the crew had not been properly trained in a runaway stab procedure because the airline considered it to be a statistically insignificant event.

The degradation of pilot training and standards is a worldwide problem. It is being driven in large part by the beancounter mentality that attempts to justify every cost. Unfortunately this approach forgets that there are some costs that cannot be easily quantified, and eventually a price will be paid in bent metal and broken bodies. Sadly, even if the industry will not openly admit it, there seems to be an underlying assumption that there is an acceptable hull loss rate and that little will change until the body count goes up.

[737 Driver]

Originally Posted by MurphyWasRight

.
On UAS:

Does it include "land at nearest suitable airport".?

No, it does not, a glaring omission in this operator's opinion. I am being told that our UAS procedures are going to be updated. I suspect this will take longer than necessary because of the liability issues (i.e. any change may be interpreted as an admission of fault). Personally, I don't think any of the crews at my airline would continue blissfully on with even one good airspeed indicator, much less none.

[rog747]

Originally Posted by 737 Driver

I do not disagree in theory, but IMHO, the reality is that the training standards dictated by Boeing have been catering to the lowest common denominator for years. They have a strong incentive to sell aircraft across the entire spectrum of airlines and countries regardless of the depth and quality of their aviation heritage. Requiring a higher level of demonstrated skills for the operator potentially translates into higher costs and lost sales.

Sadly, this thought process does not stop at Boeing. I recently had an opportunity to fly with FO who was relatively new to the 737. During our trip, we discussed a number of issues that had come out of the recent MAX crashes. During this conversation, he confessed that before these accidents, he did not even know the stab trim wheel had a stowable handle and had never been trained in its use. Think about that for a moment. Also consider that a freshly-minted 737 Captain would have received the exact same training.

After I picked my jaw up off the floor, I proceeded to personally give the FO the training he had missed. Afterwords, I shared my concerns with my Fleet Manager and told him in no uncertain terms that our training programs needed a thorough review. The Fleet Manager replied that this was already in progress, and stated that our training programs were constantly being reviewed for improvement. He added a telling remark, however, that stab trim malfunctions had never been a statistically significant problem at our airline, implying of course that the training events our pilots are exposed to constantly needed to be justified by historical data. I told him that if the MAX accident had occurred at our airline, the family of those who perished would have been rightfully angered if it had come to be known that the crew had not been properly trained in a runaway stab procedure because the airline considered it to be a statistically insignificant event.

The degradation of pilot training and standards is a worldwide problem. It is being driven in large part by the beancounter mentality that attempts to justify every cost. Unfortunately this approach forgets that there are some costs that cannot be easily quantified, and eventually a price will be paid in bent metal and broken bodies. Sadly, even if the industry will not openly admit it, there seems to be an underlying assumption that there is an acceptable hull loss rate and that little will change until the body count goes up.

737driver one of the most enlightening and concise posts in this thread recently

[Smythe]

There's no date on that Boeing statement. Was it issued before or after the Ethiopian crash?

It showed up on the website on May 05, 2019. at around noon.

Strictly from a technical perspective, however, it needs to be pointed out that if a 737 crew were to receive an "AOA Disagree" message and go to the appropriate NNC, that checklist would simply direct them to the "IAS Disagree" checklist and/or the "ALT Disagree" checklist as appropriate

Well, that was my question, if you did get the alert, what would you do? With MCAS, it appears that it uses one specific AoA vane? (or just one vane) I am unclear on this.
Cutting off MCAS does not solve the issue of the reason it was created in the first place, lift from the nacelles.

[Alchad]

Originally Posted by GordonR_Cape

Thanks for the link. It gets worse:

Quote extract...

But in the last several weeks, Boeing has been saying something different. Mr. Tajer said the company recently told American pilots that the system would not alert pilots about any sensor disagreement until the aircraft is 400 feet above the ground.

Unquote

My emphasis added. This is a critical point that was touched on previously. It is impossible to get a reliable AOA value until there is significant forward airspeed. Plus it takes time to compare the two values, and trigger the AOA disagree warning. By then the aircraft is airborne. Its a bit too late. If it was fitted and worked, which it didn't.

Im surprised this didn't attract more comments, perhaps it got missed in the flurry of recent posts? Just wondered how much of a "wow" comment it is, and also whether the 400 feet limit would presumably also apply to MCAS as it would suggest that an input check is performed before the AOA signal is allowed to be used? There was talk way way back about a height limit on MCAS intervention but don't think it ever got resolved.

Alchad

[MurphyWasRight]

Originally Posted by 737 Driver

During our trip, we discussed a number of issues that had come out of the recent MAX crashes. During this conversation, he confessed that before these accidents, he did not even know the stab trim wheel had a stowable handle and had never been trained in its use. Think about that for a moment. Also consider that a freshly-minted 737 Captain would have received the exact same training.
..
He (fleet manager) added a telling remark, however, that stab trim malfunctions had never been a statistically significant problem at our airline, implying of course that the training events our pilots are exposed to constantly needed to be justified by historical data.
...

This supports my impression that the manual trim system as originally designed has been continually degraded both by training and physical changes such as smaller wheel and removal of separate auto only cutout option.
At the same time the sources of runaway trim have increased as more automatic systems use the trim, NG sts and other? , MAX + mcas and other?.

Can not help but think that the safety analysis used a faulty evaluation of manual trim system, mechanical and pilot training, when assessing MCAS impact, falling back on grandfathered original analysis of effectiveness/useability.

[ws737]

Originally Posted by Lonewolf_50

@737 Diver:
The issue here, having just gone through the last 7 pages of this thread, remains a multi party setting up of this crew (as I see it).
1. Boeing and various companies were chasing a dollar/profit objective, and the AoA miscompare "alert" was apparently optional equipment.

2. A primary flight control is moved by an aircraft sub system with no pilot in put, but (as has been discussed at length) a number of ways of disabling it.

3. Training on this subsystem: of questionable quality. Doubly so due to wide variation between air line companies in how much (in terms of time and money) they invest in their crews, not just for the upgrade to Max but in general.

4. Crew training(??) / inexperience becoming an international norm.

5. Over-reliance on automation becoming an international norm.

6. Arriving at your points in your latest post, (none of which seem unreasonable to me, but I don't fly 737) the above mentioned factors suggest that unless you are in a company who values crew competence, and puts money / time / resources toward that core value, your crews are open to being set up - not only for the startle factor increasing a challenge, but incomplete systems knowledge (and practice with it) getting in the way of timely and correct decision making when dealing with a systems malfunction. Years ago when I was running sim training the ability to do some "free play" at the end of a session to test where a crew got oversaturated with systems malfunctions/emergencies was good training, and a lot of crews really appreciated them.

Meme/clue for the non pilots in the audience here: when a malfunction turns into an emergency (or a fatal crash) to simply blame the pilots is to overlook that layers of human endeavor and responsibility that got them to that point.

7. (Pax Britannica made some interesting points previous but I lost my train of thought). The cockpit gradient in a given cockpit does not develop in isolation from cockpit / corporate culture, which is also informed by larger cultural issues regarding authority. It is unclear how that played out for ET to me, and is one of those hard to quantify factors.

8. A company (be it ET, Lion, or perhaps if things had played out differently, United or American?) has a powerful financial motive to move the blame indicator arrow to point ONLY at the manufacturer. (And the single point of failure issue that looks to be a root causal factor gives them fair grist for that mill). Some of this is cultural, some of this is purely financial due to how litigation works.

9. In the time between Lion Air and ET: what training, what systems training, and what crew training with related malfunctions did this crew have? What are the effects of negative training, and how do those play out in a cockpit?

10. Recency and upset training was mentioned above. I'll offer an idea here: any malfunction that is related to the movement of primary flight controls is subject to a recency factor (as seen in the AF 447 accident).

Were they, the crew in ET, set up?
At least in part, I offer that the answer is yes. The system that set them up all of the world's airline companies are a part of, and are core players in. So too are regulators, and nations.

I can't disagree with the general point that the pitch and power chorus are making (this singing group is once again on stage was they were for most of the AF 447 discussion on PPRuNe) . Power plus attitude equals performance.
But are people really being trained that way anymore?
Are their behaviors being incentivized to ground their operation of aircraft with that fundamental principle foremost?
If not, why not?
The corporations who make their money in this business (be it manufacturing, operating, or training people to operate the equipment) need to answer that question. So who is holding them all to account?

Aside: I do not believe that there is now an international standard of what a professional pilot is - I have seen some appeal to that thought - no matter how badly I wish that were true.
There may once have been such a standard. (But hey, all that is now needed is a concierge, eh? Tech is magic! (/sarcasm off))
There's a lot of lip service paid to it, though, and professional pilots (those who are the real deal) are rightly dismayed to see the profession that learned hard lessons over the course of a century, under attack. The two dead men (and their passengers) from ET are casualties in a war that seems to be going on between price and professionalism, and the use of automation to replace human function.

I agree 100%...+1

[safetypee]

Alchad, Ethiopian airliner down in Africa

No ‘wow’ response because an AOA Disagree alert has little value for pilots. There is no third system to resolve the ambiguity - which AoA is correct - not known; what can I do about it - nothing, info only (or distraction). Furthermore an alert could contribute to misdiagnosis in the UAS drill; stick shake + EFIS low speed awareness on the ‘left side’, this might incorrectly bias thoughts to the left, - speed correct - aircraft is slow.
Whereas the Air Data Disagree alerts for Speed / ALT each have a third, standby instrument which the crew can use to arbitrate and choose the most valid pairing; standby + right side = right Speed is best.
So without means of arbitration the AoA alert has little value.

From an engineering view, particularly with hindsight, AoA Disagree could have been used in the original MCAS design. It wasn’t because that design assumed that the effects in the accident would not occur - all of which were incorrect.
Limiting these problems using AoA Disagree provides an engineering solution. However for the crew, retaining the AoA alert would not clarify the accuracy of AoA - so don’t display the alert nor the optional gauge when there is disagreement.
The most important absence is the annunciation that MCAS is inoperative, which with a caution that flight in some (few) areas of the fight envelope requiring careful handing.

[wheelsright]

What is the big issue?

Among others, 737 Driver is getting a lot of flack in this thread because some people see his contributions as trying to deflect blame away from Boeing and on to the pilots. I would not be so harsh, but suggest that pilots tend to look at issues from a pilots perspective. There is little doubt that disabling electric trim at an early stage would have prevented these accidents. However, one could also suggest that disabling electric trim before all flights would have prevented these accidents or simply grounding the MAX series would have prevented the accidents.

A little flippant yes, but it is the reason for some emotional statements. None of the pilots could reasonably be accused of anything other than an innocent mistake. Boeing on the other hand did not make an innocent mistake they took a calculated risk... a risk that did not pay off. It was not an innocent mistake at all. It is the difference between doing something wrong and making a mistake. 737 Driver accepts that MCAS should not be enabled when AoA disagree (or so I understand). Boeing must have understood this issue long before Lion Air, and certainly after Lion Air.They should have grounded the MAX to resolve the matter. That is why a little emotion is creeping into this thread.

737 Driver is tending to argue pitch and power is the solution but underplaying that pitch cannot be achieved if it is running away. Earlier on in the thread, 737 Driver said runaway could be arrested by the knee of the pilot... not sure that is following procedure or is even possible. 737 Driver is insistent that electric trim can be used to counteract MCAS. If the publications of Boeing are accurate, that is true.

However, it is difficult to believe that the in the Lion Air and ET302 incidents that the pilots were not trying to use the thumb switches to counteract MCAS. Maybe they were not, maybe they, for some reason, thought that they could not. I still have some doubts because it does not seem to add up. What is certain is that had they reacted quicker and hit the cut-out switches earlier, they probably would have been in good shape. Of course, the FDR suggests that the pilots did not use much electric trim, but it is not conclusive because thumb switch input is not recorded.

I am a little skeptical why the voice transcripts of ET302 have not been published. I suspect some legal eagles have stuck their oar in. The transcript could be exculpatory or damning to some of the parties. Perhaps some parties do not want those kinds of conclusions made just yet. It is probably for the best to take a little more time to do a thorough investigation, despite the public desire to know what happened. All too much truth has come out already for Boeing's liking. Perhaps the tip of the iceberg?

[MemberBerry]

Originally Posted by 737 Driver

If I recall correctly, the "5 second" remark was specifically in reference to a certain set of steps on the runaway stab trim checklist. Apparently there is a "demo" video on YouTube that gives the impression that it takes longer, and someone was under the impression that this length of time was one of the things working against the crew. I was simply pointing out that it could have been done quicker. In another post, however, I also pointed out that the crew could take all the time they needed to get the aircraft back to neutral trim as long as one of the pilots was, yes, FLYING THE AIRCRAFT and managing the trim using the yoke switch.

I recall it a bit differently. It was a longer exchange starting with a comment about the first step in your mantra. I claimed that "turning off the magic" is made more difficult on the MAX, because it contains an additional bit of magic that can't be turned off without losing manual electric trim as well. As a solution I proposed introducing a software update (since a hardware change like rewiring the cutout switches differently would be more costly), which would allow the pilots to disable MCAS and other types automatic electric trim without losing manual electric trim. You replied that the new feature would involve more troubleshooting, and the philosophy is that pilots should not troubleshoot problems, and procedurally they shouldn't fiddle with the cutout switches. I replied that the runway stabilizer memory items already look a bit like troubleshooting, saying "do this, if that doesn't work do that, if that doesn't work finally do that". What I meant was that a bit more troubleshooting in addition to the existing troubleshooting steps wouldn't be the end of the world. For example the "fiddling" part could be added as deferred items. Especially since two sets of pilots experiencing MCAS did just that. They fiddled with the cutout switches after initially disabling stabilizer trim.

Then you replied that those "troubleshooting" steps in the memory items can be done in "under 5 seconds". I felt that sounded a bit like an exaggeration. First of all the pilot flying would have to hold firmly the control column. This means he would have to rely on the pilot not flying to actually execute rest of the memory items, since his hands are busy. I assumed the pilot not flying will not just do the rest of the items blindly and hastily, without confirming them with the pilot flying first, so I didn't see how that that can be done in under 5 seconds. So I replied with a partial transcript of a Mentour video, demonstrating the execution of the memory items, where the "troubleshooting" part took 43 seconds. Mentour is a captain with over 10000 hours experience on the 737. He is also a line training captain, type rating instructor, and type rating examiner.

I agree that in the demo video they were not executing the memory items as fast as possibile, and in a real emergency it would probably be wise to execute them faster. What I didn't mention was that, including problem identification, it actually took them 83 seconds between the start of the runaway and using the cutout switches, including the time needed to identify the problem. The full transcript and the link to the video by Mentour is in one of my older posts in this thread, here: Ethiopian airliner down in Africa

It is possible Mentour was exaggerating by making the execution of the memory items too long and too formal. Or you were exaggerating with your "under 5 seconds" claim. Or both. Alternatively there may be some misunderstanding on my part.

After your "don't tell me how to fly the plane" post I took a break from posting yesterday to allow the things to calm down. Even if I don't agree with everything you say, I appreciate your informed contributions to this forum, and that you are trying not to let the discussion go "into the weeds". As for me, I'm just a passenger that is interested in this MAX saga. I only post when somebody makes claims that are clearly wrong without anybody contradicting him (for example the "the pilots allowed the plane to reach 500 knots without doing anything" post, or the "pilots in the previous Lion Air flight immediately used the cutout switches"), or when I feel that the facts or opinions I post are valuable to the discussion.

Unfortunately I'm not very good at interacting with people, and I'm sorry if my posts may seem disrespectful, I am just giving my honest opinion.


Now to different topic, the AoA disagree light. First, we have the revelation that Boeing didn't know that it doesn't work if the AoA display optional feature was not installed. OK, that's understandable, it's a bug that has slipped through testing. It happens. Then they say they analyzed the impact and they concluded it doesn't affect the safety. OK, fair enough, a lot of pilots have expressed similar opinions.

But then there is decision to not inform either the FAA or the airlines about the problem. Hiding this information IS actually a safety issue, in my opinion. OK, let's say 95% of the pilots don't care about the AoA disagree light. But the remaining 5% might be confused in a AoA disagree situation, assuming the disagree light works correctly and there is nothing wrong with the angle of attack vanes. Instead those pilots may suspect issues with the pitot probes the static ports or some other issues when they get a false stick shaker.

And even the part about the disagree indicator itself not being a safety feature is debatable. For example, after the previous Lion Air flight, if this indicator worked properly its activation might have been recorded in the flight and maintenance log, and the maintenance crew might have tested replaced the faulty vane, and we wouldn't have the Lion Air accident.

But then, the cherry on top is Boeing not even knowing how their planes work. First claiming that when the related option is installed AoA disagree light can activate on the ground, then realizing after a few months that actually you need to be at least 400 feet above ground level for it to activate. I don't even know what to say about that. They didn't give the contractor that implemented that piece of software exact specifications about how it should work? If they did, how is it possible they didn't know? Did somebody later assume it works just like on the NG, without checking the documentation before telling the airlines? I assume it works on the ground for NGs, during the takeoff roll, otherwise I can't find any reasonable explanation for this surreal display of incompetence on Boeings part.