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hamiltondaniel
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 2:47 am

SheikhDjibouti wrote:
The only other option is the grand conspiracy; Ethiopia knows it was a bomb, but is busy hiding all the evidence..... :roll:


Another either/or fallacy (sixth or seventh in last three pages, since I started counting).

There are a million options you're ignoring because you already assume you've got the answer.

The most obvious option is that we don't know what happened, and that even the people on the ground have been there for less than thirty six hours so they probably don't know what happened either.

This stuff takes time. The publicly available data is weird and contradicts most of the hypotheses being tossed around here (if it was MCAS, why were they doing 500mph in level flight only 1000' off the ground?; if it wasn't MCAS, why was it so hard to gain altitude when they seem to have had plenty of power to haul ass?) We don't have access to the best available data, and even those who do have very little data yet.

I'm going to officially proclaim myself the logic checker of this thread. Somebody needs to.
 
JoeCanuck
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 2:51 am

LTC8K6 wrote:
Improving MCAS doesn't necessarily make it the cause of the crash, though.


From what I recall from the Lion thread, MCAS is disabled when flaps are lowered and/or auto pilot is engaged. As well, it can be manually disengaged intermittently with the electric trim switch on the yoke, and permanently disabled with a pair of cutoff switches on the yoke.

On the lion aircraft, according to the fdr, flaps were fully retracted by 2000'. From what I recall of the FR24 data, the plane didn't seem to climb above 1500' agl. If the sop is similar, then it's likely that the flaps would have been remained extended, so MCAS would not have been enabled. As well, Ethiopian has said that its pilots were aware of the manual MCAS disabling techniques.

To me, it seems unlikely that MCAS would have been a significant contributor to the accident...leaving myriad other more likely possibilities...none of which there seems to be evidence for.
What the...?
 
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SheikhDjibouti
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 2:54 am

32andBelow wrote:
Explosion that made the plane uncontrollable. It was at 1000ft. How big do you think the field would be?

Shaky wrote:
Please explain how you know the aircraft was at 1,000 ft?
Please explain the inconsistent speed data at take-off?
Please explain the handling issues reported shortly after take-off?

32andBelow wrote:
Could easily have been an altimeter bomb. Or detonated by a passenger.
The NTSB just got there. I doubt Ethiopian knows much of anything tbh. I think NTSB and Boeing will take the primary lead. The easiest explanation is usually the most likely.

I asked three questions.
Simple questions
You avoided answering any of them.

I did not ask about the nature of the device. Or who would take the lead in the investigation.

And your "easiest explanation" is only the most likely if you refuse to answer the questions that will demonstrate how absurd it is.
Let's try again.
Please explain how you know the aircraft was at 1,000 ft? (justification for the small debris field after an alleged in-flight explosion)

Please explain the inconsistent speed data at take-off? (i.e. before any altimeter bomb could possibly explode)

Please explain the handling issues reported shortly after take-off? (ditto)
Nothing to see here; move along please.
 
hivue
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 2:58 am

JoeCanuck wrote:
and permanently disabled with a pair of cutoff switches on the yoke.


They are on the center pedestal.
"You're sitting. In a chair. In the SKY!!" ~ Louis C.K.
 
TTailedTiger
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 3:01 am

Gonzalo wrote:
Aerolíneas Argentinas, Aeroméxico, Gol and many other carriers are grounding the fleet of 738Max in the last few hours. This is a major trouble for Boeing and the stocks will continue to fall if the company doesn’t take a strong action to make a public commitment to solve any problem and warrant the safety of the model in a very short time.
I love Boeing planes and this is really sad, but let’s face it, the things have been managed horribly from a public view standpoint and the lack of a strong response by Boeing is not helping.

Rgds.
G.


What do you want them to do? Lie? They don't know the cause of the Lion Air or Ethiopian crash either.

You can be sure that Boeing is doing everything in their power to make sure their product isn't defective. Did you not see that they have the Max out doing test flights today?
 
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Starlionblue
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 3:03 am

GEUltraFan9XGTF wrote:
Do pilots have to sign an NDA about performance characteristics?


Manuals and performance software are proprietary and our employment contracts have verbiage about the confidentiality of company information.

So while we don't sign an NDA on performance data per se, the effect is the same.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
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Starlionblue
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 3:05 am

Reefwiz wrote:
Can't believe that no one has posted this update from Reuters.

So much for 1700 posts of theory and fantasy.

Looks more like fire and or explosion or hull intrusion is a strong possibility.

https://www.reuters.com/article/us-ethi ... SKBN1QS1LJ

Tamirat Abera, 25, was walking past the field at the time. He said the plane turned sharply, trailing white smoke and items like clothes and papers, then crashed about 300 meters away.

Half a dozen witnesses interviewed by Reuters in the farmland where the plane came down reported smoke billowing out behind, while four of them also described a loud sound.

“It was a loud rattling sound. Like straining and shaking metal,” said Turn Buzuna, a 26-year-old housewife and farmer who lives about 300 meters (328 yards) from the crash site.

Paper and clothing dropping from the sky as the plane trailed smoke and sparks (fire)... doesn't sound like software, eh?


As has been stated repeatedly in this admittedly long thread, eyewitnesses are notoriously unreliable. Unless someone has video, all that stuff is hearsay at this point.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
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SheikhDjibouti
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 3:06 am

hamiltondaniel wrote:
SheikhDjibouti wrote:
The only other option is the grand conspiracy; Ethiopia knows it was a bomb, but is busy hiding all the evidence..... :roll:


Another either/or fallacy (sixth or seventh in last three pages, since I started counting).

You have taken my quote completely out of context.
Your logic is so wrong I don't even know where to begin.
Go back (way beyond my post), and start with the basic idea that it is some other nutcase who is pinning his hopes on a bomb. Not me.
That should set you on the right track.

hamiltondaniel wrote:
I'm going to officially proclaim myself the logic checker of this thread. Somebody needs to.

Good luck with that.... after you have put your own house in order. :banghead:
Nothing to see here; move along please.
 
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Starlionblue
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 3:09 am

FredrikHAD wrote:
khobar95 wrote:
... The Aviation Herald learned that the loss of altitude had been caused by two angle of attack sensors having frozen in their positions ...


What puzzles me is that the computers in these advanced aircraft cannot make use of the vast amount of sensors in a more intelligent way. It is (I know it is) entirely possible to give a pretty good estimate of AoA based on other input than only AoA sensors. It could be derived from throttle, actual thrust (is that available by the way?), rudder deflection, speed, altitude and perhaps some other data. This type of "secondary" data could be used to warn the pilots that a set of sensors MAY be wrong and give them the option to deactivate systems that are dependant on them, or automatically switch to another sensor if available. In the case with both AoA sensors frozen, the system could even decide to use the derived AoA and warn that this is the case.

A MAX8/9 that has had no extraordinary stick input, just rotated at a speed that is "normal", is accelerating as expected and is climbing at an expected rate cannot all of a sudden go into an angle of attack of epic proportions.

I sometimes refer to the CRJ-200PF crash in Sweden Jan 8th 2016. The captain's "Primary Flight Display showed a pitch angle of 15 degrees nose up with speed and altitude remaining unchanged" [quote from the investigation]. The #1 Inertial Reference System (IRS) (displayed on the left side PFD) had started indicating a pitch that was both untrue and completely unrealistic. Sadly, the captain didn't even consult the FO but started pitching down, causing a dive, and from there everything "went south". The captain was probably startled by the high pitch and started to "counteract" that by lowering the nose. The FO didn't understand a thing because his PFD was showing the correct pitch. Both pilots must have felt all was normal before the captain saw the incorrect pitch on the PFD. If the pitch had been that high, speed would have decreased and/or altitude increased, all possible to "sense" by a human, and, more interestingly, by the computers!!! Humans can be fooled into believing all is normal (spatial disorientation, somatogravic illusion and other phenomena) but computers with enough sensors can decide that at least one sensor is incorrect, perhaps even determine which one. In this case, as speed, altitude and one IRS were consistent with each other, that would wash out pitch from the #1 IRS as the culprit. One action could be to stop displaying pitch on the left PFD, or draw a red cross over it, still displaying the false value. A warning that the #1 IRS was probably giving a false value should be easy to produce.

I do understand that such modifications cannot be done easily, but if the values from the present systems are fed to a separate computer, it could at least warn the pilots that something is wrong, and they can be aided into deciding how to troubleshoot that. This type of "secondary" or "synthetic" readings should be considered in the future at least. If this had been the case in the MAX, it might just have averted both crashes.

/Fredrik


Possible, but I don't know how reliable the calculation might be compared to the simple expedient of having triple redundant AoA sensors. More modern aircraft have triple redundant AoA as a matter of course, but the 737MAX is based on a design from the Jurassic Era...

As GalaxyFlyer says, pilots in the loop should also detect inconsistent data.



zuckie13 wrote:
gia777 wrote:
https://finance.yahoo.com/news/pilots-reported-issues-us-boeing-204120870.html
This article explain how the autpilot at B737MAX have issues

Airline pilots on at least two U.S. flights have reported that an automated system seemed to cause their Boeing 737 Max planes to tilt down suddenly.

The pilots said that soon after engaging the autopilot on Boeing 737 Max 8 planes, the nose tilted down sharply. In both cases, they recovered quickly after disconnecting the autopilot.

As described by the pilots, however, the problem did not appear related to a new automated anti-stall system that is suspected of contributing to a deadly October crash in Indonesia.

The Max 8 is at the center of a growing global ban by more than 40 countries following a second fatal crash, this time in Ethiopia, in less than five months. In the U.S., however, the Federal Aviation Administration and airlines continued to permit the planes to fly.

American Airlines and Southwest Airlines operate the 737 Max 8, and United Airlines flies a slightly larger version, the Max 9. All three carriers vouched for the safety of Max aircraft on Wednesday

The pilot reports were filed last year in a data base compiled by NASA. They are voluntary safety reports and do not publicly reveal the names of pilots, the airlines or the location of the incidents.

It was unclear whether the accounts led to any actions by the FAA or the pilots' airlines.

In one report, an airline captain said that immediately after putting the plane on autopilot, the co-pilot called out "Descending," followed by an audio cockpit warning, "Don't sink, don't sink!"

The captain immediately disconnected the autopilot and resumed climbing.

"With the concerns with the MAX 8 nose down stuff, we both thought it appropriate to bring it to your attention," the captain wrote. "Best guess from me is airspeed fluctuation" due to a brief weather system overwhelming the plane's automation.

On another flight, the co-pilot said that seconds after engaging the autopilot, the nose pitched downward and the plane began descending at 1,200 to 1,500 feet (365 to 460 meters) per minute. As in the other flight, the plane's low-altitude-warning system issued an audio warning. The captain disconnected autopilot, and the plane began to climb.


Possible the planes were not trimmed well when AP was engaged. Maybe pilot engaged the AP and trim was so bad it nosed down because it had to make a major adjustment?


That's not really how autopilots work. If an adjustment is needed by the autopilot, it will be made gradually like any other autopilot input.


skuds wrote:
Condolences to the families of the lost.

Good evening, My first post... Long time lurker... Please be gentle.
After slogging thru this thread the last couple of days, I’ve learned a lot... Coo-does to most!

Referencing FredrikHAD‘s comments, and acknowledging that I have no experience in aircraft flight systems... However, I do have 35 years of human space flight ground systems engineering and management experience in Houston.

I’m wondering if there is systems integration issues between the 738’s aircraft’s autopilot system and the seemingly add-in MCAS that today’s s/w upgrade may address. The autopilot transition’s dipping of the aircraft’s nose is most disconcerting.

Questions I have include: Do all the sensors live on a network using standard communications protocols or are they point-to-point, e.g., is it possible to efficiently add additional redundant sensors? Is the base MCAS capable of taking on additional inputs? Is there a general communications pathway between the autopilot, flap settings and MCAS that goes beyond “I’m on and therefore you’re off”? e.g., Do they interrogate each other and pass key flight parameters?

Or... Is this a closed system that would require reengineering of each subsystem, a bazillion $s and recertifications?
Or, could this software “patch” address some or all of these key integration issues?


Networks using standard comms protocols, virtual machines and all that stuff are a relatively new thing in aviation. For example, the A350 uses one but the A330 does not. I doubt the 737MAX has such a thing since it would probably force certification as a new type.

You've hit the nail on the head about software patches. Relatively "easy" on a fully FBW aircraft. On a cable and pulley aircraft designed in a time when networked sensors were not even a glimmer on the horizon, not so much.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
skuds
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 3:16 am

LTC8K6 wrote:
Improving MCAS doesn't necessarily make it the cause of the crash, though.


Of course... But in reading through the thread, there seems to be an upset to flight conditions induced by the transition to/from MCAS that consumes the flight crew’s attention each time and most importantly at critical times relative to flight safety. It appears that the MCAS, flaps and autopilot don’t know the flight parameters their companion/partner system is dealing with at the time of transition. Requiring the flight crew to negotiate that transition seems to distract them from critical tasks that maybe a flight safety priority at that time. I understand that flaps management is a crew responsibility... But it seems that the automated flight management design should obviate flight conditions upsets when transitioning from one automated flight control system to another or provide a simple buffering procedure.
 
SDFspectator
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 3:21 am

32andBelow wrote:
spacecadet wrote:
Reefwiz wrote:
Can't believe that no one has posted this update from Reuters.

So much for 1700 posts of theory and fantasy.


It was posted dozens of pages ago, before Reuters even learned of it.

Paper and clothing dropping from the sky as the plane trailed smoke and sparks (fire)... doesn't sound like software, eh?


If the witness is correct, which they are more than likely not.

That's why not a lot of credence has been given to it. Witnesses - especially *one* witness - are very rarely reliable. If there's a pattern among dozens of witnesses, then ok, you look for general things you can take away from that. But very few people - even if they know anything about aviation - can accurately describe what they're seeing in an unusual situation like this. In the Northwest 255 accident, for example, there were other pilots who watched that flight take off and swore that the flaps were down. They weren't. And those were *pilots*. You expect a layperson to do better?

Ignore the witnesses until there's some corroborating evidence, which there is not right now. A single witness statement should be treated as at best "interesting" until proven otherwise, but it's certainly no smoking gun, or even necessarily evidence of anything.

He said half a dozen witnesses but you cut that off his quote.


The people who saw what happened were not educated on airliners.net university, therefore are unreliable and don't know the difference between white smoke and black smoke. I think that's what he was trying to say.
 
dragon6172
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 3:49 am

NWNightfly wrote:
WIederling wrote:
Interpretation:
MCAS trimmed high and the activated autopilot corrected that ASAP.
This would indicate that MCAS and flight displays get wrong ( increased AoA) information
while the AP gets the correct one. That is a real can of worms, man!


Except isn't it pretty much SOP throughout the world to activate the autopilot before fully retracting the flaps? In which case, once again, MCAS would have never been engaged.

Two things. MCAS would never trim high, resulting in AP nosing over when engaged. And the issue in both crashes is the other sensors that are more than likely preventing the autopilot from being engaged. I.e, probably cant engage autopilot if airspeeds are faulty or AOA probe is faulty.

It would seem to me, that it would be good practice to leave the flaps extended until it can be verified in the climb that airspeed, aoa data, etc is good.
Phrogs Phorever
 
tvarad
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 4:07 am

From the Ethiopian Airlines CEO through Richard Quest (their travel reporter), CNN is reporting that the airplane had flight control issues:

https://twitter.com/CNNnewsroom/status/ ... index.html

Surely the pilots would have gotten the memo on the MCAS issue after the Lion Air crash and must have tried the fix(es) so if they still couldn't fly it, there's a high probability that the loss of control points to something else.
 
slider
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 4:11 am

For high clarity, just recapping the past 37 pages, we don't know anything about this crash, factually speaking.

Carry on.
 
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Starlionblue
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 4:12 am

NWNightfly wrote:
WIederling wrote:
1010101 wrote:
This article https://m.huffpost.com/us/entry/us_5c88 ... 0ddae54075 has two reports of a sudden pitch down after the autopilot is engaged. This would support the notion that something more than MCAS is involved.

Edited to add this direct link to the pilot asrs report. https://www.documentcloud.org/documents ... 10/a486269


Interpretation:
MCAS trimmed high and the activated autopilot corrected that ASAP.
This would indicate that MCAS and flight displays get wrong ( increased AoA) information
while the AP gets the correct one. That is a real can of worms, man!


Except isn't it pretty much SOP throughout the world to activate the autopilot before fully retracting the flaps? In which case, once again, MCAS would have never been engaged.


It is not SOP throughout the world. You can engage the autopilot before or after flap retraction, and even during, based on environmental conditions, traffic, familiarity with the departure, situational awareness, what the PF feels like doing on the day...
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Waterbomber2
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 4:14 am

I have a theory that could explain the AOA sensor malfunction indication and the crashes, while also explaining why MCAS is wrongly accused of being the main culprit.

If you look at the position of the engine intakes on the MAX 8, they have been brought forward and up, to maintain ground clearance despite installing a larger fan.
The MCAS system has been added to counter the balance effects compared to the -800, but let's leave this aside for a minute and focus purely on aerodynamics.
My theory is that due to the new position and size of the fan, where the fan intake's upper edge is protruding above the wing's extrados even when the aircraft is level VS. ram air, the MAX 8's engines may be too high and sucking a lot of ram air that previously came into contact with the wing to contribute to lift generation, causing the wing to locally stall prematurely. In addition, it's possible that the position of the new engines vis a vis the wings is causing ram air to become turbulent ahead of the wing and creating a shadow effect for the wing sections situated behind the engine.
Basically, my theory is that the higher position of the engine intakes is reducing the flight envelope of the MAX 8 by causing premature, undetected stalls.
In my flight training days, we would practice the powered stall recovery with the instructor and this reminds me of that phenomenon.

-it explains why the Lion Air aircraft went out of envelope in the climb after take-off: an already high angle of attack during climb, followed by a local undetected stall of the wing, which expands into a power-on stall potentially supported by flap retraction.
-The AOA sensors indicate a malfunction because they are outside preset parameters. Essentially, they are not malfunctioning, but they appear to be malfunctioning as the aircraft is in a stall but not within the expected parameters of a stall.
-The trim may be running amock and contributing to a difficult recovery, again, because it is operating outside the parameters.


Please look at the high position of the engine intakes and compare them to the -800.
They are crazy high and imagine how they will be shadowing a good portion of the wing's leading edge in a climb with a higher angle of attack.

Image

https://static.seattletimes.com/wp-cont ... 60x967.jpg
Last edited by Waterbomber2 on Wed Mar 13, 2019 4:23 am, edited 2 times in total.
 
ikramerica
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 4:15 am

maui19 wrote:
There is something that has been nagging at me about both these crashes. In both cases, the pilots were struggling with the aricraft, but did seem to be overcoming the problem (MCAS) as shown by their continuing to climb, albeit haltingly. But at the end, both planes encountered something that caused them to nosedive. I feel like this is a big piece of the puzzle is yet to be identified. Perhaps the final problem occurs when they try to turn the AC to return to the airport. I think there's more to this than just MCAS and a bad sensor. But who knows.

That's a big part of it. If you bank to go home while not disabling the MCAS, and it malfunctions again, it seems as if you are doomed.

Lion Air. The Lion crew did not "overcome the problem" but seemed to fail to understand the problem. Now, the argument is that they didn't know about MCAS, but there is a known similar troubleshooting procedure for what MCAS was DOING to them that they didn't follow, namely, cutting off the trim switches. The locations are the same on the 738 (though names slightly different). The previous Lion crew did just that. Its a systemic failure within Lion, from crew training, to maintenance, to communication of faults and incidents, to briefing, that lead to the dispatch of an unreliable aircraft and the unpreparedness of the flight crew to deal with it.

As for ET, we have no idea what went wrong, what caused the crash, whether it was MCAS. Anyone who says it is is guessing. Even educating guessing at this point without FDR or CVR readout is too unreliable. But there are other situations, not just MCAS malfunction, where banking the aircraft while not in control of the underlying problem spells doom.
Of all the things to worry about... the Wookie has no pants.
 
ikramerica
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 4:23 am

Waterbomber2 wrote:
I have a theory that could explain the AOA sensor malfunction indication and the crashes, while also explaining why MCAS is wrongly accused of being the main culprit.

If you look at the position of the engines on the MAX 8, they have been brought forward and up, to maintain ground clearance despite installing a larger fan.
The MCAS system has been added to counter the balance effects compared to the -800, but let's leave this aside for a minute and focus purely on aerodynamics.
My theory is that due to the new position and size of the fan, where the fan intake's upper edge is protruding above the wing's extrados even when the aircraft is level VS. ram air, the MAX 8's engines may be too high and sucking a lot of ram air that previously came into contact with the wing to contribute to lift generation, causing the wing to locally stall prematurely. In addition, it's possible that the position of the new engines vis a vis the wings is causing ram air to become turbulent ahead of the wing and creating a shadow effect for the wing sections situated behind the engine.
Basically, my theory is that the higher position of the engines is reducing the flight envelope of the MAX 8 by causing premature, undetected stalls.
In my flight training days, we would practice the powered stall recovery with the instructor and this reminds me of that phenomenon.

-it explains why the Lion Air aircraft went out of envelope in the climb after take-off: an already high angle of attack during climb, followed by a local undetected stall of the wing, which expands into a power-on stall potentially supported by flap retraction.
-The AOA sensors indicate a malfunction because they are outside preset parameters. Essentially, they are not malfunctioning, but they appear to be malfunctioning as the aircraft is in a stall but not within the expected parameters of a stall.
-The trim may be running amock and contributing to a difficult recovery, again, because it is operating outside the parameters.

Please look at the position of the engines and compare them to the -800.
They are crazy high and imagine how they will be way above the wing's leading edge in a climb with a higher angle of attack.


But how on earth would this not have been experienced by Boeing in modeling, wind tunnel testing, regular flight testing, envelope establishment, and 2 years in service around the world?

I would still think, that even if what you are saying is correct, it has to be enhanced by some OTHER event that compounds it, some sort of malfunction.
Of all the things to worry about... the Wookie has no pants.
 
AvFanNJ
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 4:28 am

Waterbomber2 wrote:
I have a theory that could explain the AOA sensor malfunction indication and the crashes, while also explaining why MCAS is wrongly accused of being the main culprit.

If you look at the position of the engines on the MAX 8, they have been brought forward and up, to maintain ground clearance despite installing a larger fan.
The MCAS system has been added to counter the balance effects compared to the -800, but let's leave this aside for a minute and focus purely on aerodynamics.
My theory is that due to the new position and size of the fan, where the fan intake's upper edge is protruding above the wing's extrados even when the aircraft is level VS. ram air, the MAX 8's engines may be too high and sucking a lot of ram air that previously came into contact with the wing to contribute to lift generation, causing the wing to locally stall prematurely. In addition, it's possible that the position of the new engines vis a vis the wings is causing ram air to become turbulent ahead of the wing and creating a shadow effect for the wing sections situated behind the engine.
Basically, my theory is that the higher position of the engines is reducing the flight envelope of the MAX 8 by causing premature, undetected stalls.
In my flight training days, we would practice the powered stall recovery with the instructor and this reminds me of that phenomenon.

-it explains why the Lion Air aircraft went out of envelope in the climb after take-off: an already high angle of attack during climb, followed by a local undetected stall of the wing, which expands into a power-on stall potentially supported by flap retraction.
-The AOA sensors indicate a malfunction because they are outside preset parameters. Essentially, they are not malfunctioning, but they appear to be malfunctioning as the aircraft is in a stall but not within the expected parameters of a stall.
-The trim may be running amock and contributing to a difficult recovery, again, because it is operating outside the parameters.


Please look at the position of the engines and compare them to the -800.
They are crazy high and imagine how they will be way above the wing's leading edge in a climb with a higher angle of attack.

Your theory is really more of a hunch at this point. Don't you think Boeing tested scale models of the MAX in the wind tunnel for possible aerodynamic anomalies and then tried to validate those results later in the actual flight tests? Your "theory" is interesting but it appears to me to be largely speculation. But let's see if the investigations back up your claim.
 
tvarad
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 4:30 am

Don't know how far this data is accurate but someone has graphed flight statistics between the two MAX crashes on twitter in a follow up to the CNN report mentioned above:

https://twitter.com/Engineer19952/statu ... 5916211206

Check it out and make of it what you will.
 
Waterbomber2
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 4:32 am

ikramerica wrote:
Waterbomber2 wrote:
I have a theory that could explain the AOA sensor malfunction indication and the crashes, while also explaining why MCAS is wrongly accused of being the main culprit.

If you look at the position of the engines on the MAX 8, they have been brought forward and up, to maintain ground clearance despite installing a larger fan.
The MCAS system has been added to counter the balance effects compared to the -800, but let's leave this aside for a minute and focus purely on aerodynamics.
My theory is that due to the new position and size of the fan, where the fan intake's upper edge is protruding above the wing's extrados even when the aircraft is level VS. ram air, the MAX 8's engines may be too high and sucking a lot of ram air that previously came into contact with the wing to contribute to lift generation, causing the wing to locally stall prematurely. In addition, it's possible that the position of the new engines vis a vis the wings is causing ram air to become turbulent ahead of the wing and creating a shadow effect for the wing sections situated behind the engine.
Basically, my theory is that the higher position of the engines is reducing the flight envelope of the MAX 8 by causing premature, undetected stalls.
In my flight training days, we would practice the powered stall recovery with the instructor and this reminds me of that phenomenon.

-it explains why the Lion Air aircraft went out of envelope in the climb after take-off: an already high angle of attack during climb, followed by a local undetected stall of the wing, which expands into a power-on stall potentially supported by flap retraction.
-The AOA sensors indicate a malfunction because they are outside preset parameters. Essentially, they are not malfunctioning, but they appear to be malfunctioning as the aircraft is in a stall but not within the expected parameters of a stall.
-The trim may be running amock and contributing to a difficult recovery, again, because it is operating outside the parameters.

Please look at the position of the engines and compare them to the -800.
They are crazy high and imagine how they will be way above the wing's leading edge in a climb with a higher angle of attack.


But how on earth would this not have been experienced by Boeing in modeling, wind tunnel testing, regular flight testing, envelope establishment, and 2 years in service around the world?

I would still think, that even if what you are saying is correct, it has to be enhanced by some OTHER event that compounds it, some sort of malfunction.


I think that it can be explained by the fact that modelling is not advanced enough or does not take into account the air sucked in by an engine as this was not as much of a factor in previous designs.
For instance in wind tunnel testing, the engines are just static elements and don't have a fan in them that sucks in ram air.
 
dragon6172
Posts: 1129
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 4:47 am

Waterbomber2 wrote:
I have a theory that could explain the AOA sensor malfunction indication and the crashes, while also explaining why MCAS is wrongly accused of being the main culprit.

If you look at the position of the engine intakes on the MAX 8, they have been brought forward and up, to maintain ground clearance despite installing a larger fan.
The MCAS system has been added to counter the balance effects compared to the -800, but let's leave this aside for a minute and focus purely on aerodynamics.
My theory is that due to the new position and size of the fan, where the fan intake's upper edge is protruding above the wing's extrados even when the aircraft is level VS. ram air, the MAX 8's engines may be too high and sucking a lot of ram air that previously came into contact with the wing to contribute to lift generation, causing the wing to locally stall prematurely. In addition, it's possible that the position of the new engines vis a vis the wings is causing ram air to become turbulent ahead of the wing and creating a shadow effect for the wing sections situated behind the engine.
Basically, my theory is that the higher position of the engine intakes is reducing the flight envelope of the MAX 8 by causing premature, undetected stalls.
In my flight training days, we would practice the powered stall recovery with the instructor and this reminds me of that phenomenon.

-it explains why the Lion Air aircraft went out of envelope in the climb after take-off: an already high angle of attack during climb, followed by a local undetected stall of the wing, which expands into a power-on stall potentially supported by flap retraction.
-The AOA sensors indicate a malfunction because they are outside preset parameters. Essentially, they are not malfunctioning, but they appear to be malfunctioning as the aircraft is in a stall but not within the expected parameters of a stall.
-The trim may be running amock and contributing to a difficult recovery, again, because it is operating outside the parameters.


Please look at the high position of the engine intakes and compare them to the -800.
They are crazy high and imagine how they will be shadowing a good portion of the wing's leading edge in a climb with a higher angle of attack.

Image

https://static.seattletimes.com/wp-cont ... 60x967.jpg

The FDR traces for Lion crash show the AOA vane began to give erroneous data before the aircraft even took off. The sensor data was bad, no hidden stalls
Phrogs Phorever
 
ikramerica
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 4:55 am

tvarad wrote:
From the Ethiopian Airlines CEO through Richard Quest (their travel reporter), CNN is reporting that the airplane had flight control issues:

https://twitter.com/CNNnewsroom/status/ ... index.html

Surely the pilots would have gotten the memo on the MCAS issue after the Lion Air crash and must have tried the fix(es) so if they still couldn't fly it, there's a high probability that the loss of control points to something else.

ET claims they trained on the MCAS. But flight control issues doesn't mean MCAS. Aircraft without MCAS have flight control issues too.
Of all the things to worry about... the Wookie has no pants.
 
User avatar
Starlionblue
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 4:55 am

Waterbomber2 wrote:
ikramerica wrote:
Waterbomber2 wrote:
I have a theory that could explain the AOA sensor malfunction indication and the crashes, while also explaining why MCAS is wrongly accused of being the main culprit.

If you look at the position of the engines on the MAX 8, they have been brought forward and up, to maintain ground clearance despite installing a larger fan.
The MCAS system has been added to counter the balance effects compared to the -800, but let's leave this aside for a minute and focus purely on aerodynamics.
My theory is that due to the new position and size of the fan, where the fan intake's upper edge is protruding above the wing's extrados even when the aircraft is level VS. ram air, the MAX 8's engines may be too high and sucking a lot of ram air that previously came into contact with the wing to contribute to lift generation, causing the wing to locally stall prematurely. In addition, it's possible that the position of the new engines vis a vis the wings is causing ram air to become turbulent ahead of the wing and creating a shadow effect for the wing sections situated behind the engine.
Basically, my theory is that the higher position of the engines is reducing the flight envelope of the MAX 8 by causing premature, undetected stalls.
In my flight training days, we would practice the powered stall recovery with the instructor and this reminds me of that phenomenon.

-it explains why the Lion Air aircraft went out of envelope in the climb after take-off: an already high angle of attack during climb, followed by a local undetected stall of the wing, which expands into a power-on stall potentially supported by flap retraction.
-The AOA sensors indicate a malfunction because they are outside preset parameters. Essentially, they are not malfunctioning, but they appear to be malfunctioning as the aircraft is in a stall but not within the expected parameters of a stall.
-The trim may be running amock and contributing to a difficult recovery, again, because it is operating outside the parameters.

Please look at the position of the engines and compare them to the -800.
They are crazy high and imagine how they will be way above the wing's leading edge in a climb with a higher angle of attack.


But how on earth would this not have been experienced by Boeing in modeling, wind tunnel testing, regular flight testing, envelope establishment, and 2 years in service around the world?

I would still think, that even if what you are saying is correct, it has to be enhanced by some OTHER event that compounds it, some sort of malfunction.


I think that it can be explained by the fact that modelling is not advanced enough or does not take into account the air sucked in by an engine as this was not as much of a factor in previous designs.
For instance in wind tunnel testing, the engines are just static elements and don't have a fan in them that sucks in ram air.



I don't buy it. Fluid Dynamics modelling is super advanced, plus there is wind tunnel testing. IMHO there is no way this sort of thing would have been simply "missed".
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
slider
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 5:05 am

trpmb6 wrote:
PlanesNTrains wrote:
slider wrote:

Well, this could be a tragic by-product of trying to upgrade a warmed-over 50 year old airframe instead of having designed a new clean sheet airplane. WN drove the train on the NG from the start--Boeing should have taken that singular opportunity to thank them but tell them that their fleet commonality wasn't going to dictate much necessary airframe improvements for the 737. So then you have Frankenstein at work, with the 737-900ER, and then the MAX with shoehorning a significantly different engine on it and having to programatically compensate for aerodynamic compromise. Separate rant altogether about how Boeing's desire to placate a major customer in WN actually hurt them in the long run. And we may--*may*--be seeing the ultimate price for that now, which would be tragic.


I'm not a big fan of the MAX but how do you fault Boeing/WN for the NG when it was an incredible market success? Are you saying it would have been even more successful and profitable had they done a clean sheet back in the 90's?

With the MAX, it is what it is. Aside from what we know about the MCAS system, it doesn't seem to be an abject failure - just not the best.



Furthermore, the market dictated the development of the MAX not the other way around. It's not like Boeing went out and said, here's the max, take it or leave it. They developed what the market wanted. The market didn't want to wait for a new single aisle aircraft and it didn't want to pay the sticker price of a new single aisle aircraft.


I utterly disagree. They capitulated to the "market" in the sense they gave in to WN when the NG was being developed in the first place. Boeing has a history of allowing far too much latitude in carriers' ordering options. When the NG was launched, they gave in to WN for their "need" to have type commonality, and the die was cast...and it shouldn't have been. As a consequence, design took a back seat to sales--globally. And that continues today because they perpetuated an aging airframe with new engines even then.

Now, the development costs for a modified variant are obviously much less, so we all understand Boeing's approach, but it remains questionable as to whether they ought to have made a clean sheet decision even then, even considering the monster development to do so. IF--and I say this cautiously--this ET302 accident is related to the MCAS system, there are some roots to follow back and that would be even more tragic. A bridge too far, Boeing. IF that's the case.

*Sidenote....has anyone found bag data for this airplane yet? Load shift? Unlikely but a thought.
 
slider
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 5:07 am

Starlionblue wrote:
Waterbomber2 wrote:
ikramerica wrote:

But how on earth would this not have been experienced by Boeing in modeling, wind tunnel testing, regular flight testing, envelope establishment, and 2 years in service around the world?

I would still think, that even if what you are saying is correct, it has to be enhanced by some OTHER event that compounds it, some sort of malfunction.


I think that it can be explained by the fact that modelling is not advanced enough or does not take into account the air sucked in by an engine as this was not as much of a factor in previous designs.
For instance in wind tunnel testing, the engines are just static elements and don't have a fan in them that sucks in ram air.



I don't buy it. Fluid Dynamics modelling is super advanced, plus there is wind tunnel testing. IMHO there is no way this sort of thing would have been simply "missed".


It wasn't missed, clearly, because we've been talking about the MCAS thing for dozens of pages now. But the implementation, training and systems integration of it possibly *could* have been overlooked to some degree. We'll know soon enough.
 
downdata
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 5:09 am

Per Bloomberg: Ethiopia wanted to send the flight-data and cockpit-voice recorders to the UK AAIB instead of NTSB in the US

https://www.bloomberg.com/news/articles ... emium-asia

Blackbox to U.K. or U.S.? (10:58 a.m.)

Ethiopia wanted to send the flight-data and cockpit-voice recorders to the U.K.’s Air Accidents Investigation Branch to recover the data, causing U.S. investigators to hold intense behind-the-scenes talks to bring the remains to America, the Wall Street Journal reported, citing people familiar with the matter. U.S. officials wanted to have the recorders sent to the National Transportation Safety Board on grounds that American government experts would provide the most reliable and accurate data downloads, according to the report. The U.S. hadn’t received a final decision as of late Tuesday, according to the Journal.


This would be pretty much unprecedented right? Given this is a US made plane.
Last edited by downdata on Wed Mar 13, 2019 5:12 am, edited 3 times in total.
 
spacecadet
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 5:10 am

32andBelow wrote:
He said half a dozen witnesses but you cut that off his quote.


No, he chose to quote one witness - as did Reuters. Let's see what the actual pattern is among the other witnesses when asked non-leading questions that aren't designed to get matching answers by someone not in the media.
I'm tired of being a wanna-be league bowler. I wanna be a league bowler!
 
axio
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 5:22 am

downdata wrote:
Ethiopia wanted to send the flight-data and cockpit-voice recorders to the U.K.’s Air Accidents Investigation Branch to recover the data, causing U.S. investigators to hold intense behind-the-scenes talks to bring the remains to America, the Wall Street Journal reported, citing people familiar with the matter. U.S. officials wanted to have the recorders sent to the National Transportation Safety Board on grounds that American government experts would provide the most reliable and accurate data downloads, according to the report. The U.S. hadn’t received a final decision as of late Tuesday, according to the Journal.[/code]

This would be pretty much unprecedented right? Given this is a US made plane.


If I understand right from many episodes of Mayday, Ethiopia is the nation responsible for the investigation. They would expect representatives from the nations of the aircraft manufacturer and the engine manufacturer as well as the nation of the operating airline if it were a different nation. If they lack the facilities/skills then they are free to engage other investigatory boards at their discretion. For instance, the Ukraine handed the investigation of MH17 to the Netherlands. Perhaps they have an existing relationship with the AAIB?
Time for a new viewing deck at AKL!
 
dragon6172
Posts: 1129
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 5:24 am

downdata wrote:
Per Bloomberg: Ethiopia wanted to send the flight-data and cockpit-voice recorders to the UK AAIB instead of NTSB in the US

https://www.bloomberg.com/news/articles ... emium-asia

Blackbox to U.K. or U.S.? (10:58 a.m.)

Ethiopia wanted to send the flight-data and cockpit-voice recorders to the U.K.’s Air Accidents Investigation Branch to recover the data, causing U.S. investigators to hold intense behind-the-scenes talks to bring the remains to America, the Wall Street Journal reported, citing people familiar with the matter. U.S. officials wanted to have the recorders sent to the National Transportation Safety Board on grounds that American government experts would provide the most reliable and accurate data downloads, according to the report. The U.S. hadn’t received a final decision as of late Tuesday, according to the Journal.


This would be pretty much unprecedented right? Given this is a US made plane.

I believe country of manufacture has right to observe the investigation, doesnt mean the black boxes have to come to US for download
Phrogs Phorever
 
navjotgill45
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 5:27 am

Apologies if asked before, thread too longto check. I'm still confused as to why MCAS would even operate in an AoA disagree situation. Surely the certifiers would have considered a "faulty airpseed/AoA etc" situation? Would love to be enlightened on this by knowledgeble posters (pilots/mechanics etc.)?
 
2175301
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 5:39 am

downdata wrote:
Per Bloomberg: Ethiopia wanted to send the flight-data and cockpit-voice recorders to the UK AAIB instead of NTSB in the US

https://www.bloomberg.com/news/articles ... emium-asia

Blackbox to U.K. or U.S.? (10:58 a.m.)

Ethiopia wanted to send the flight-data and cockpit-voice recorders to the U.K.’s Air Accidents Investigation Branch to recover the data, causing U.S. investigators to hold intense behind-the-scenes talks to bring the remains to America, the Wall Street Journal reported, citing people familiar with the matter. U.S. officials wanted to have the recorders sent to the National Transportation Safety Board on grounds that American government experts would provide the most reliable and accurate data downloads, according to the report. The U.S. hadn’t received a final decision as of late Tuesday, according to the Journal.


This would be pretty much unprecedented right? Given this is a US made plane.


Actually not unprecedented at all. The USA NTSB is generally recognized around the world for their expertise and independence. They actually get involved in many more overseas crash investigations than most people imagine; and they commonly download CVR's and FDR's for other countries.

As this is an American Made Aircraft the NTSB has a right to at least be an observer to the investigation. It would be routine for them to request that they do the downloads. However, Ethiopia (or any country doing the investigation) can make their own decision on where they are downloaded, and by who. I have no problem with the UK doing this work - neither will the NTSB if that is the choice of Ethiopia.

Have a great day,
 
PlanesNTrains
Posts: 9524
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 5:41 am

downdata wrote:
Per Bloomberg: Ethiopia wanted to send the flight-data and cockpit-voice recorders to the UK AAIB instead of NTSB in the US
.


Makes sense to me, and probably the best decision for everybody.

hamiltondaniel wrote:
I'm going to officially proclaim myself the logic checker of this thread. Somebody needs to.


Nice knowing ya.

slider wrote:
trpmb6 wrote:
PlanesNTrains wrote:

I'm not a big fan of the MAX but how do you fault Boeing/WN for the NG when it was an incredible market success? Are you saying it would have been even more successful and profitable had they done a clean sheet back in the 90's?

With the MAX, it is what it is. Aside from what we know about the MCAS system, it doesn't seem to be an abject failure - just not the best.



Furthermore, the market dictated the development of the MAX not the other way around. It's not like Boeing went out and said, here's the max, take it or leave it. They developed what the market wanted. The market didn't want to wait for a new single aisle aircraft and it didn't want to pay the sticker price of a new single aisle aircraft.


I utterly disagree. They capitulated to the "market" in the sense they gave in to WN when the NG was being developed in the first place. Boeing has a history of allowing far too much latitude in carriers' ordering options. When the NG was launched, they gave in to WN for their "need" to have type commonality, and the die was cast...and it shouldn't have been. As a consequence, design took a back seat to sales--globally. And that continues today because they perpetuated an aging airframe with new engines even then.

Now, the development costs for a modified variant are obviously much less, so we all understand Boeing's approach, but it remains questionable as to whether they ought to have made a clean sheet decision even then, even considering the monster development to do so. IF--and I say this cautiously--this ET302 accident is related to the MCAS system, there are some roots to follow back and that would be even more tragic. A bridge too far, Boeing. IF that's the case.

*Sidenote....has anyone found bag data for this airplane yet? Load shift? Unlikely but a thought.


To be blunt, this is bullshit. If you are going to claim that a decision a quarter century ago to develop a 737 derivative that became a massive commercial success with an impeccable safety record is somehow responsible for the crashes we are discussing, then I think you've lost perspective.

Boeing had a decision to make in 2011 - clean sheet or re-engine. They chose re-engine. Within "re-engine" they had complete flexibility to spend as much or as little as they wanted to develop what became the MAX. That decision is entirely on their shoulders and is completely independent of the NG development. Yes, had they gone clean-sheet in the 90s then we wouldn't be having this discussion for obvious reasons, but that's irrelevant to reality. Reality is Boeing had options and the MAX is what they chose in 2011.

To blame anything in our current discussion on Boeing capitulating to WN back in the early 90's is simply gratuitous and self-serving.
-Dave


MAX’d out on MAX threads. If you are starting a thread, and it’s about the MAX - stop. There’s already a thread that covers it.
 
RandallStephens
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 5:41 am

Waterbomber2 wrote:
I have a theory that could explain the AOA sensor malfunction indication and the crashes, while also explaining why MCAS is wrongly accused of being the main culprit.

If you look at the position of the engine intakes on the MAX 8, they have been brought forward and up, to maintain ground clearance despite installing a larger fan.
The MCAS system has been added to counter the balance effects compared to the -800, but let's leave this aside for a minute and focus purely on aerodynamics.
My theory is that due to the new position and size of the fan, where the fan intake's upper edge is protruding above the wing's extrados even when the aircraft is level VS. ram air, the MAX 8's engines may be too high and sucking a lot of ram air that previously came into contact with the wing to contribute to lift generation, causing the wing to locally stall prematurely. In addition, it's possible that the position of the new engines vis a vis the wings is causing ram air to become turbulent ahead of the wing and creating a shadow effect for the wing sections situated behind the engine.
Basically, my theory is that the higher position of the engine intakes is reducing the flight envelope of the MAX 8 by causing premature, undetected stalls.
In my flight training days, we would practice the powered stall recovery with the instructor and this reminds me of that phenomenon.

-it explains why the Lion Air aircraft went out of envelope in the climb after take-off: an already high angle of attack during climb, followed by a local undetected stall of the wing, which expands into a power-on stall potentially supported by flap retraction.
-The AOA sensors indicate a malfunction because they are outside preset parameters. Essentially, they are not malfunctioning, but they appear to be malfunctioning as the aircraft is in a stall but not within the expected parameters of a stall.
-The trim may be running amock and contributing to a difficult recovery, again, because it is operating outside the parameters.


Please look at the high position of the engine intakes and compare them to the -800.
They are crazy high and imagine how they will be shadowing a good portion of the wing's leading edge in a climb with a higher angle of attack.



Airplanes have had root mounted engine intakes for ages without issue. Not sure why the cfd run for the 787 would have problems on a 737 sized aircraft. They are operating at similar Re
 
Pluto707
Posts: 37
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 5:41 am

navjotgill45 wrote:
Apologies if asked before, thread too longto check. I'm still confused as to why MCAS would even operate in an AoA disagree situation. Surely the certifiers would have considered a "faulty airpseed/AoA etc" situation? Would love to be enlightened on this by knowledgeble posters (pilots/mechanics etc.)?
Not only in an AoA disagree situation, aparently i will work even in a GPWS situation...jeez...
 
downdata
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 5:43 am

2175301 wrote:

As this is an American Made Aircraft the NTSB has a right to at least be an observer to the investigation. It would be routine for them to request that they do the downloads. However, Ethiopia (or any country doing the investigation) can make their own decision on where they are downloaded, and by who. I have no problem with the UK doing this work - neither will the NTSB if that is the choice of Ethiopia.

Have a great day,


The new reporting does say this is "causing U.S. investigators to hold intense behind-the-scenes talks to bring the remains to America, the Wall Street Journal reported", so even at the surface level, there seems to be some contention there.
 
TWA1985
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 5:47 am

I know this isn’t 100% accurate but it still gives me chills. The animation makes it feel so real, especially with the sound effects.

https://youtu.be/q5QnJ9OHkBI
Be Young. Be Wild. Be Free.
 
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Finn350
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 5:48 am

downdata wrote:
2175301 wrote:

As this is an American Made Aircraft the NTSB has a right to at least be an observer to the investigation. It would be routine for them to request that they do the downloads. However, Ethiopia (or any country doing the investigation) can make their own decision on where they are downloaded, and by who. I have no problem with the UK doing this work - neither will the NTSB if that is the choice of Ethiopia.

Have a great day,


The new reporting does say this is "causing U.S. investigators to hold intense behind-the-scenes talks to bring the remains to America, the Wall Street Journal reported", so even at the surface level, there seems to be some contention there.


It doesn’t matter whether the data is downloaded in the UK and USA, so I doubt if the situation is as tense as described in the quote above.
 
Backseater
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 5:50 am

One interesting aspect of that flight is that the a/c was never able to gain significant altitude over the ground.
The FR24 Data is partial due to line of sight limitation with the nearest ADSB receiver. But several witnesses described a plane flying over, not falling vertically, at least not until its fateful end.
Witnesses have been largely ignored because witnesses are often unreliaable. They saw white smoke, probably the overwing condensation trails. They heard a high pitched noise, probably because the engines were at max power as pilots attempted to gain altitude. I assume that the whole flight was at low altitude with speed and altitude excursions.
If MCAS is going to be brought in as an actor, then AP had to be off and flaps retracted, clearly given the a/c speed. Pilots were flying manually.
At this point, everybody brings AoA sensor fault, since only one sensor is used as input to MCAS. That is of course one possibility.
I just wonder about any other possibilities.
For instance, what if the a/c had been incorrectly loaded, thus moving the CG too far forward. What would pilots do to convert their speed into more altitude?
Put max power and pull on the stick?
But given the stress, were they not likely to exceed some AOA threshold that would then trigger MCAS to increase the down trim.
And this would repeat until...
 
Reefwiz
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 5:51 am

spacecadet wrote:
32andBelow wrote:
He said half a dozen witnesses but you cut that off his quote.


No, he chose to quote one witness - as did Reuters. Let's see what the actual pattern is among the other witnesses when asked non-leading questions that aren't designed to get matching answers by someone not in the media.



Just to be accurate, Reuters interviewed SIX villagers. FOUR reported seeing smoke trailing the aircraft and TWO heard metallic rattling noises in addition to seeing the smoke. Sounds to me like a hull breech by lithium batteries, compressed gas cylinders, hazardous materials or an old fashioned b0mb....probably in cargo hold.
 
musicrab
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 5:53 am

"The U.S. hadn’t received a final decision as of late Tuesday [Ethiopia wanted to send the flight-data and cockpit-voice recorders to the U.K.’s Air Accidents Investigation Branch]" Oh dear. So the blackboxes sit on a shelf in limbo. Get the damn data downloaded.
 
32andBelow
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 5:53 am

Reefwiz wrote:
spacecadet wrote:
32andBelow wrote:
He said half a dozen witnesses but you cut that off his quote.


No, he chose to quote one witness - as did Reuters. Let's see what the actual pattern is among the other witnesses when asked non-leading questions that aren't designed to get matching answers by someone not in the media.



Just to be accurate, Reuters interviewed SIX villagers. FOUR reported seeing smoke trailing the aircraft and TWO heard metallic rattling noises in addition to seeing the smoke. Sounds to me like a hull breech by lithium batteries, compressed gas cylinders, hazardous materials or an old fashioned b0mb....probably in cargo hold.

Altimeter bomb set to 1000agl
 
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MillwallSean
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 5:58 am

downdata wrote:
The new reporting does say this is "causing U.S. investigators to hold intense behind-the-scenes talks to bring the remains to America, the Wall Street Journal reported", so even at the surface level, there seems to be some contention there.


Hmm, this is getting out of control.
If we cant trust national bodys and believe that corporate interests yield to much power, then present system of certification will break down and lead to alot of complications. Not sure I am to happy with that.
Also not to sure I understand anyones motive here. The Ethiopians choose where to send it. it is their investigation and their choice.
Why would the NTSB push to bring the boxes to the US should the Ethiopians want it done in the UK. the UK is as good as the NTSB so the rationale for this would give raise to a lot of unwarranted and unnecessary speculation. Whats hidden? Whos interests are protected?
And if that's the start or the cooperation between the assisting Americans and the lead agents from Ethiopia it doesn't bode well for the investigation.

Id say a lot of the blame for this can be placed squarely on the the FAA. They have been questioned, in regards to their independence, and that might be the issue here. A belief that there is a risk for bias should it be sent to the US.
However this is the American NTSB whom I haven't heard people question in regards to competence or bias. Anyway, if this becomes a trend it doesn't bode well for the neutrality and expertise that's expected from all the worlds investigating bodies.

Touch wood this is just the media making a hen out of a feather.
No One Likes Us - We Dont Care.
 
RandallStephens
Posts: 48
Joined: Thu Sep 06, 2018 6:21 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 5:58 am

Two different witness accounts. What I like is that they're not using big words to describe what they saw, they are using plain folk speech. To me that's believable.


https://youtu.be/DnCtVuLn5iY

https://youtu.be/3A9uHGqiyUA

Does mcas make a plane burn, too?
 
Bobloblaw
Posts: 2406
Joined: Fri Jan 13, 2012 1:15 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 6:07 am

MillwallSean wrote:
downdata wrote:
The new reporting does say this is "causing U.S. investigators to hold intense behind-the-scenes talks to bring the remains to America, the Wall Street Journal reported", so even at the surface level, there seems to be some contention there.


Hmm, this is getting out of control.
If we cant trust national bodys and believe that corporate interests yield to much power, then present system of certification will break down and lead to alot of complications. Not sure I am to happy with that.
Also not to sure I understand anyones motive here. The Ethiopians choose where to send it. it is their investigation and their choice.
Why would the NTSB push to bring the boxes to the US should the Ethiopians want it done in the UK. the UK is as good as the NTSB so the rationale for this would give raise to a lot of unwarranted and unnecessary speculation. Whats hidden? Whos interests are protected?
And if that's the start or the cooperation between the assisting Americans and the lead agents from Ethiopia it doesn't bode well for the investigation.

Id say a lot of the blame for this can be placed squarely on the the FAA. They have been questioned, in regards to their independence, and that might be the issue here. A belief that there is a risk for bias should it be sent to the US.
However this is the American NTSB whom I haven't heard people question in regards to competence or bias. Anyway, if this becomes a trend it doesn't bode well for the neutrality and expertise that's expected from all the worlds investigating bodies.

Touch wood this is just the media making a hen out of a feather.

Why should the black boxes be analyzed in the UK?
 
Elshad
Posts: 104
Joined: Wed May 23, 2018 8:24 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 6:12 am

Both those witnesses mention smoke or fire coming from the tail. Interesting.
 
LTC8K6
Posts: 1587
Joined: Fri Jun 05, 2009 8:36 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 6:16 am

tvarad wrote:
From the Ethiopian Airlines CEO through Richard Quest (their travel reporter), CNN is reporting that the airplane had flight control issues:

https://twitter.com/CNNnewsroom/status/ ... index.html

Surely the pilots would have gotten the memo on the MCAS issue after the Lion Air crash and must have tried the fix(es) so if they still couldn't fly it, there's a high probability that the loss of control points to something else.


Perhaps the recent focus and training on MCAS caused the ETH crew to assume that was the problem with their plane, but maybe it wasn't.

Maybe the crew even did the takeoff a different way?
 
User avatar
Finn350
Posts: 1601
Joined: Tue Jul 09, 2013 4:57 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 6:18 am

RandallStephens wrote:
Two different witness accounts. What I like is that they're not using big words to describe what they saw, they are using plain folk speech. To me that's believable.


https://youtu.be/DnCtVuLn5iY

https://youtu.be/3A9uHGqiyUA

Does mcas make a plane burn, too?


"Before falling down, the plane rotated two times in the air, and it had some smoke coming from the back then, it hit the ground and and exploded."

From the translation it is not clear what he meant. I would interpret that the plane was cartwheeling in the ground, and had some smoke coming as result of the cartwheeling, and then exploded. I don't see how it could have rotated two times when still airborne.
 
LTC8K6
Posts: 1587
Joined: Fri Jun 05, 2009 8:36 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 6:20 am

Finn350 wrote:
RandallStephens wrote:
Two different witness accounts. What I like is that they're not using big words to describe what they saw, they are using plain folk speech. To me that's believable.


https://youtu.be/DnCtVuLn5iY

https://youtu.be/3A9uHGqiyUA

Does mcas make a plane burn, too?


"Before falling down, the plane rotated two times in the air, and it had some smoke coming from the back then, it hit the ground and and exploded."

From the translation it is not clear what he meant. I would interpret that the plane was cartwheeling in the ground, and had some smoke coming as result of the cartwheeling, and then exploded. I don't see how it could have rotated two times when still airborne.


Aerial photos don't seem to show any evidence of cartwheeling along the ground, though.
You just never know about witness testimony.
 
User avatar
Starlionblue
Posts: 20367
Joined: Fri Feb 27, 2004 9:54 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Wed Mar 13, 2019 6:25 am

Reefwiz wrote:
spacecadet wrote:
32andBelow wrote:
He said half a dozen witnesses but you cut that off his quote.


No, he chose to quote one witness - as did Reuters. Let's see what the actual pattern is among the other witnesses when asked non-leading questions that aren't designed to get matching answers by someone not in the media.



Just to be accurate, Reuters interviewed SIX villagers. FOUR reported seeing smoke trailing the aircraft and TWO heard metallic rattling noises in addition to seeing the smoke. Sounds to me like a hull breech by lithium batteries, compressed gas cylinders, hazardous materials or an old fashioned b0mb....probably in cargo hold.


They could very well have discussed it amongst themselves, strengthening and spreading a meme about the perceived sequence of events.

Again, because it bears repeating. Eyewitness accounts are notoriously unreliable, especially if they are coming from non-experts on the subject matter. Our brains play tricks on us every day, and they are very good at constructing plausible, if not entirely authentic memories based on our preconceptions and biases. This is especially true when experiencing dramatic, stressful and/or traumatic events.
Last edited by Starlionblue on Wed Mar 13, 2019 6:29 am, edited 1 time in total.
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