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kalvado
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 12, 2019 9:54 pm

XRAYretired wrote:
kalvado wrote:
XRAYretired wrote:

That my be so, and may prevent any 'charges' being levelled. but, also worth mentioning that the Boeing procedure in the AD did not prevent a catestrophic outcome on the one occasion it was necessary.

In particular, it did not mandate re-setting trim to 'neutral' prior to the cut-out action, which perhaps it should have and secondly, it made no mention of Flaps. Albeit, the procedure is for un-commanded AND having occurred, it may well have been appropriate to mention not to go flaps up (if they are down) in the condition of IAS disagree, Alt disagree and Stick Shaker to prevent the condition occurring at all.

Either of these may have prevented the catastrophic outcome.

Ray

One can easily see why return to trim was not there: Boeing basically instructed to use runaway trim procedure - and in genuine runaway may not allow that. Setting up a new procedure could be too much. Same for flaps on airspeed disagree - it is a change for one of critical procedures. Once enough of such changes are accumulated....


I bow to your knowledge. Perhaps grounding after Lion Air should have been up for consideration after all?

Ray

Thanks for the laughter! I think these are low hanging fruit.
As for grounding.... hindsight is always 20/20. right? I struggle with putting together a justifiable regulatory case before some analysis at Boeing; and apparently Boeing management will never approve multi-month grounding in such situation whatever analysis said.
Could there be any middle ground, with Boeing sending out more than 1 paragraph of instructions? Maybe. Or maybe not.
I even think that with some luck, Boeing could have MCAS 2.0 rubber stamped and installed before second crush - and never face any scrutiny... Basically they bet on that - and lost.
 
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PW100
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 12, 2019 9:56 pm

XRAYretired wrote:
OldAeroGuy wrote:
maint123 wrote:
The lion air crash can be termed a accident due to ignorance but the ethiopian crash is criminal neglect.
Boeing was too busy deflecting and blaming the crew and maintenance to take a serious look at their plane.
Anyone defending them should also be made accessories to their actions.
I will repeat, laws of physics are unforgiving. You can't fool them.

Very bold statements to make since the FAA/Boeing issued Emergency Air Worthiness Directive 2018-23-51 on November 7, 2018.

That my be so, and may prevent any 'charges' being levelled. but, also worth mentioning that the Boeing procedure in the AD did not prevent a catestrophic outcome on the one occasion it was necessary.

In particular, it did not mandate re-setting trim to 'neutral' prior to the cut-out action, which perhaps it should have and secondly, it made no mention of Flaps . . .
Either of these may have prevented the catastrophic outcome.

Ray


I'm not sure if the trimming instruction would have changed anything with respect to the ET accident: the crew did do just that: uptrimming before cutting out electric trimming. In fact, the released FDR graphs shows the largest amount of uptrimming was right before the electric trimming was cut.

The uptrim just did not reach the "neutral" condition. And we do not know why that is. Perhaps that was an incompetent crew, as some repeatingly suggest as their favourite explanation (and then mumbling on about declining pilot standards worldwide . . . ).

It could be something else, something outside crew control. If the crew could not get more uptrim out of the electric (or manual crank) trimming, then a different procedure by Boeing (and AD mandated) would not have changed a thing. I find it believable that this could be related to Boeing delaying the release of "the MCAS fix".
Immigration officer: "What's the purpose of your visit to the USA?" Spotter: "Shooting airliners with my Canon!"
 
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PW100
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 12, 2019 10:05 pm

XRAYretired wrote:
. . . Perhaps grounding after Lion Air should have been up for consideration after all?

Ray


Probably would have been the best thing.
But I can see how commercial pressures, national pride, and especially the believe in declining pilot standards worldwide and poor maintenance (well, outside the USA) pretty much obscured reasonable analysis of the situation. Even after the second crash it took Boeing and the FAA an awful lot of time and "encouraging" to do the right thing.
Immigration officer: "What's the purpose of your visit to the USA?" Spotter: "Shooting airliners with my Canon!"
 
flybucky
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 12, 2019 10:26 pm

XRAYretired wrote:
An imagination.

Great post. I think it is a good exercise to put yourself in the pilots shoes to try to understand their decisions step by step in real time. I was planning to piece together a graphic that included FDR and CVR info, but had a busy week, maybe this weekend.

At 05:42:10, the Captain asked and the First-Officer requested radar control a vector to return and ATC approved.
At 05:42:30, ATC instructed ET-302 to turn right heading 260 degrees and the First-Officer acknowledged.
At 05:42:43, the selected heading was changed to 262 degrees.


Up until this point, I think the pilots had done a pretty good job. (Disclaimer: I am not assigning blame whatsoever. Just analyzing a couple of events in the long chain of events that led to the accident.) But I don't think they should have turned back at that point, until they stabilized the flight better. At that point, they were less than 6000 ft AGL according to Radar Alt, that's not much room to work with.

At 05:43:20, approximately five seconds after the last manual electric trim input, an AND automatic trim command occurred and the stabilizer moved in the AND direction from 2.3 to 1.0 unit in approximately 5 seconds. The aircraft began pitching nose down. Additional simultaneous aft column force was applied, but the nose down pitch continues, eventually reaching 40° nose down.

My guess is that because of the turn, they were preoccupied with more distractions, and did not notice MCAS changing the Pitch Trim until it was too late. Then it was pitching too far to recover from the dive at that speed. It's also possible that being in a turn accelerated the pitch attitude down after MCAS.

In hindsight, they had things semi-controlled (they gained 4000 ft in the past 2 mins). So they could have maintained that climb to get to at least 10,000 ft AGL, without touching anything like flaps, thrust, stab trim cutouts. Then call Maintenance for troubleshooting help. Then Maintenance could probably walk them through troubleshooting to reduce thrust, get speed down, and safely adjust the stab trim so they didn't need to pull back on the yoke. After all that was stable, then turn back to the airport.
 
flybucky
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 12, 2019 11:06 pm

PW100 wrote:
I'm not sure if the trimming instruction would have changed anything with respect to the ET accident: the crew did do just that: uptrimming before cutting out electric trimming. In fact, the released FDR graphs shows the largest amount of uptrimming was right before the electric trimming was cut. The uptrim just did not reach the "neutral" condition.

It could be something else, something outside crew control. If the crew could not get more uptrim out of the electric (or manual crank) trimming, then a different procedure by Boeing (and AD mandated) would not have changed a thing. I find it believable that this could be related to Boeing delaying the release of "the MCAS fix".

Yes, one of the open questions after the Prelim Report is why did the pilots not use Electric Trim longer? Was it because Electric Trim was ineffective?

My theory is that Electric Trim was effective. The reason I think this is because if Electric Trim was ineffective, but they wanted to raise the stab trim, they would have kept holding the Electric Trim switch up, but we would see the Pitch Trim did not change. This was not the case anywhere in the FDR data. Even near the end of the flight, when they blipped the Electric Trim up at over 350 kts, the Pitch Trim did increase in response.

So if Electric Trim was effective, why didn't they do it longer? My theory for the first time that MCAS kicked in (around 05:40:30), is that their primary concern was stalling, so they were focused on keeping thrust high and keeping the Pitch Attitude above 0 but not too high in case of stall. (And they did do that. Almost the entire flight they kept the Pitch Attitude between 0 and +10º.) So once they were able to hold Pitch Attitude above 0, they stopped Electric Trim and Cutout the Stab Trim altogether. Of course, after that Electric Trim was out of the equation.

How about at the end of the flight, why did they only blip the Electric Trim? Possible theory:
1) Bjorn's analysis was that at 360 kts at the relatively low altitude, a tiny bit of trim input will result in a violent reaction.
2) Their Pitch Attitude was positive, so that was good enough for them.
 
barney captain
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 12, 2019 11:13 pm

smartplane wrote:
barney captain wrote:
My only point in bringing up QF71/72 was to highlight that a single point of failure caused uncommanded pitch down to an assumed stall. One ADIRU provided bad AoA data.

Sound familiar?

The only reason nobody died (although some were permanently injured) was because it happened at cruise and not low level. Ironically, MCAS wouldn't activate in those cases because the A/P was on.

I'm not exonerating Boeing, but they're hardly the first to design a system that had a single point of failure. And yes, it should be fixed.

If you think Boeing committed an act of criminal negligence, then Airbus did as well.

I'll wait for the final report before making judgements, but my feeling is there will be more than one place to point a finger.

But then you do the opposite - point your finger, and use old incidents (in terms of aviation standards very old), to support your position. Because it happened to an Airbus aircraft 10 years ago, does NOT make it OK for Boeing to repeat the errors with fatal consequences in 2019.

Is there no corporate learning in the aviation industry? Should processes that allowed a 'near miss' 10 years ago, justify fatalities a decade later? Does learning only occur at Boeing when Boeing make mistakes (in other words they learn nothing from Airbus)?


Reread what I wrote - there will likely be more than one place to point a finger, as in several. Not all on Boeing, not all on the operators, not all on the pilots - just like every other crash.

And where did I write I thought it was ok for Boeing to make the same mistake? I did not, because it is not.

You incorrectly inferred everything I wrote.
Southeast Of Disorder
 
Planetalk
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 12, 2019 11:26 pm

barney captain wrote:
ELBOB wrote:
Pluto707 wrote:
Very simple final conclusion for Boeing: P.B.S. meaning: Profit Before Safety


It was ever thus. Corners were always cut and lives were lost.

Why just one actuator on the 737 Classic rudder?

Why use easily-pierced aluminium fuel lines in the belly of the 727?

Why no full hydraulic boost on the 707 rudder?



There is so much misinformation and lack of understanding in that post that it's staggering.

By why stop now?

Here, educate yourself -

https://en.wikipedia.org/wiki/Qantas_Flight_72

The ATSB's final report, issued on 19 December 2011, concluded that the incident "occurred due to the combination of a design limitation in the flight control primary computer (FCPC) software of the Airbus A330/Airbus A340, and a failure mode affecting one of the aircraft's three air data inertial reference units (ADIRUs). The design limitation meant that, in a very rare and specific situation, multiple spikes in angle of attack (AOA) data from one of the ADIRUs could result in the FCPCs commanding the aircraft to pitch down."[23]


And then it happened again -

Subsequent Qantas Flight 71 incident.

Where was the outrage and demand for grounding then?

That's right, social media hadn't taken over the minds of the masses back then.


Planes were grounded before social media you know. Are you still saying the MAX shouldn't have been grounded? We've even seen American pilots sent into the Sim to replicate these scenarios knowing exactly what was coming and exactly how they should react, and commenting afterwards that they struggled.

This thread has really shown how many people are willing to put pride, specifically national pride, or an emotional attachment to a organisation, above the actual lives of people. Some here should really ask themselves why they have reacted the way they have to over 300 people dying, as a result of something Boeing itself has admitted is a problem. Boeing is sadly run by people who have zero passion for aviation now and it shows. I'm not sure why anyone on an aviation enthusiasts site would defend people who are ruining the company and all it stands for.

And, yes I am aware there is (almost) never any one part to blame for an accident and there will recommendations for all parties. But Boeing clearly made some negligent decisions. Even one of their test pilots has said he wasn't briefed on MCAS and it seems the most basic failure modes were never tested. That is a deliberate decision. I don't think at any point anyone would the pilots made deliberately negligent decisions with the benefit of time to make them.
Last edited by Planetalk on Fri Apr 12, 2019 11:49 pm, edited 1 time in total.
 
barney captain
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 12, 2019 11:38 pm

Planetalk wrote:
barney captain wrote:
ELBOB wrote:

It was ever thus. Corners were always cut and lives were lost.

Why just one actuator on the 737 Classic rudder?

Why use easily-pierced aluminium fuel lines in the belly of the 727?

Why no full hydraulic boost on the 707 rudder?



There is so much misinformation and lack of understanding in that post that it's staggering.

By why stop now?

Here, educate yourself -

https://en.wikipedia.org/wiki/Qantas_Flight_72

The ATSB's final report, issued on 19 December 2011, concluded that the incident "occurred due to the combination of a design limitation in the flight control primary computer (FCPC) software of the Airbus A330/Airbus A340, and a failure mode affecting one of the aircraft's three air data inertial reference units (ADIRUs). The design limitation meant that, in a very rare and specific situation, multiple spikes in angle of attack (AOA) data from one of the ADIRUs could result in the FCPCs commanding the aircraft to pitch down."[23]


And then it happened again -

Subsequent Qantas Flight 71 incident.

Where was the outrage and demand for grounding then?

That's right, social media hadn't taken over the minds of the masses back then.


Planes were grounded before social media you know. Are you still saying the MAX shouldn't have been grounded? We've even seen American pilots sent into the Sim to replicate these scenarios knowing exactly what was coming and exactly how they should react, and commenting afterwards that they struggled.

This thread has really shown how many people are willing to put pride, specifically national pride, or an emotional attachment to a organisation, above the actual lives of people. Some here should really ask themselves why they have reacted the way they have to over 300 people dying, as a result of something Boeing itself has admitted is a problem. Boeing is sadly run by people who have zero passion for aviation now and it shows. I'm not sure why anyone on an aviation enthusiasts site would defend people who are ruining the company and all it stands for.


No, I never said the MAX shouldn't be grounded - it should. But the manner it which it happened was unparalleled.

What this thread has really shown is people's reading bias, which they then spin into a full fledged rant. All based on incorrect assumptions. Your entire second paragraph is a perfect example.
Southeast Of Disorder
 
Planetalk
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Fri Apr 12, 2019 11:53 pm

barney captain wrote:
My only point in bringing up QF71/72 was to highlight that a single point of failure caused uncommanded pitch down to an assumed stall. One ADIRU provided bad AoA data.

Sound familiar?

The only reason nobody died (although some were permanently injured) was because it happened at cruise and not low level. Ironically, MCAS wouldn't activate in those cases because the A/P was on.

I'm not exonerating Boeing, but they're hardly the first to design a system that had a single point of failure. And yes, it should be fixed.

If you think Boeing committed an act of criminal negligence, then Airbus did as well.

I'll wait for the final report before making judgements, but my feeling is there will be more than one place to point a finger.


Now here is the simplistic thinking. That 'airbus pitched down therefore their design and engineering was equally negligent' is absurd logic. We will see. The investigation will tell us whether the MCAS scenario was impossible to predict and could not have been expected to be considered during testing. I also don't think Airbus deliberately sought to hide anything from the pilots, but correct me if I'm wrong.
 
flybucky
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 12:01 am

Interesting article about past instances of AoA sensor damage. A recent incident occurred in March 2016 on a 737-800 NG. The pilots disabled the stall warning and continued to the destination without incident. However, after landing they realized the AoA vane was bent, and regretted not returning to the airport.

A review of public databases by Bloomberg News reveals the potential hazards of relying on the devices, which are mounted on the fuselage near the plane’s nose and are vulnerable to damage. There are at least 140 instances since the early 1990s of sensors on U.S. planes being damaged by jetways and other equipment on the ground, or striking birds in flight. In at least 25 cases in the U.S., Canada and Europe, the damage triggered cockpit alerts or emergencies.

Overall, the sensors are reliable -- they last an average of 70,000 flight hours and the number of failures is small compared to the hundreds of millions of flights. Nevertheless, they offer a window into how extensive an emergency such a failure can create.

One March 2016 incident closely resembled the recent crashes, except that the plane, an earlier 737-800 model, wasn’t equipped with MCAS and the pilots maintained control. As soon as the plane got airborne, the captain, seated on the left side, got the loud thumping noise and vibrating control column warning that the plane was about to stall, according to the NASA report. The captain’s airspeed and altitude displays disagreed with the copilot’s, indicating an error and setting off additional alerts. All of those symptoms occurred on the two recent Max crashes.

The pilots opted to continue onto their destination in spite of the multiple failures. Both the captain and the copilot said that they regretted continuing the flight and didn’t realize that they had violated their airline’s procedures by disabling the stall warning. “A return, while considered, should have been accomplished,” said the captain. Only after they landed did they realize that the captain’s angle-of-attack vane was bent for unknown reasons.

https://www.bloomberg.com/news/articles ... n-airports
 
Planetalk
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 12:03 am

barney captain wrote:
Planetalk wrote:
barney captain wrote:


There is so much misinformation and lack of understanding in that post that it's staggering.

By why stop now?

Here, educate yourself -

https://en.wikipedia.org/wiki/Qantas_Flight_72



And then it happened again -

Subsequent Qantas Flight 71 incident.

Where was the outrage and demand for grounding then?

That's right, social media hadn't taken over the minds of the masses back then.


Planes were grounded before social media you know. Are you still saying the MAX shouldn't have been grounded? We've even seen American pilots sent into the Sim to replicate these scenarios knowing exactly what was coming and exactly how they should react, and commenting afterwards that they struggled.

This thread has really shown how many people are willing to put pride, specifically national pride, or an emotional attachment to a organisation, above the actual lives of people. Some here should really ask themselves why they have reacted the way they have to over 300 people dying, as a result of something Boeing itself has admitted is a problem. Boeing is sadly run by people who have zero passion for aviation now and it shows. I'm not sure why anyone on an aviation enthusiasts site would defend people who are ruining the company and all it stands for.


No, I never said the MAX shouldn't be grounded - it should. But the manner it which it happened was unparalleled.

What this thread has really shown is people's reading bias, which they then spin into a full fledged rant. All based on incorrect assumptions. Your entire second paragraph is a perfect example.


So you think the plane should have been grounded, but complain about the very thing, social media, that possibly helped that happen sooner. Who knows without social media maybe it would not have been grounded, or it would certainly have taken longer. So you think it should have been grounded, but you would prefer the decision took longer because social media didn't exist to force The President/Boeing/FAA decision? Forgive me if I struggle with the logic there.

And please actually take on board the posts that have provided you with very good explanations of why you can't directly compare the two. In particular an investigation was rightly done of how the Airbus software came to do what it did. An investigation will similarly be done into Boeing. I suspect the findings will be rather different in terms of how foreseeable the problem was and the reasons it came to pass.

My favourite planes were all Boeings when I was growing up by the way.
 
barney captain
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 12:11 am

Groundings should be based on facts, and not driven by social media.

I'm off to work, carry on this without me.
Southeast Of Disorder
 
mjoelnir
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 12:15 am

barney captain wrote:
Groundings should be based on facts, and not driven by social media.

I'm off to work, carry on this without me.


A crash is a fact. Two crashes are two facts. Hesitation kills.

Calling a frame safe, after a crash, should be based on facts.
 
MSPNWA
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 12:24 am

mjoelnir wrote:
A crash is a fact. Two crashes are two facts. Hesitation kills.

Calling a frame safe, after a crash, should be based on facts.


Based on that simplistic logic, we should consider grounding aircraft after every crash. For sure after two in short succession, I would think.

Goes back to what I said long ago in these threads. Safety isn't based on raw stats. The aviation industry is incredibly safe because stats aren't the driver of improvements.
 
gadFly
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 1:01 am

barney captain wrote:
Groundings should be based on facts, and not driven by social media.

I'm off to work, carry on this without me.


Well, the facts are that entire fleets are grounded, not because of social media, but because even the Original Manufacturer and the main certifying agency agree something is wrong.
 
mzlin
Posts: 128
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 3:14 am

flybucky wrote:
PW100 wrote:
I'm not sure if the trimming instruction would have changed anything with respect to the ET accident: the crew did do just that: uptrimming before cutting out electric trimming. In fact, the released FDR graphs shows the largest amount of uptrimming was right before the electric trimming was cut. The uptrim just did not reach the "neutral" condition.

It could be something else, something outside crew control. If the crew could not get more uptrim out of the electric (or manual crank) trimming, then a different procedure by Boeing (and AD mandated) would not have changed a thing. I find it believable that this could be related to Boeing delaying the release of "the MCAS fix".

Yes, one of the open questions after the Prelim Report is why did the pilots not use Electric Trim longer? Was it because Electric Trim was ineffective?

My theory is that Electric Trim was effective. The reason I think this is because if Electric Trim was ineffective, but they wanted to raise the stab trim, they would have kept holding the Electric Trim switch up, but we would see the Pitch Trim did not change. This was not the case anywhere in the FDR data. Even near the end of the flight, when they blipped the Electric Trim up at over 350 kts, the Pitch Trim did increase in response.

So if Electric Trim was effective, why didn't they do it longer? My theory for the first time that MCAS kicked in (around 05:40:30), is that their primary concern was stalling, so they were focused on keeping thrust high and keeping the Pitch Attitude above 0 but not too high in case of stall. (And they did do that. Almost the entire flight they kept the Pitch Attitude between 0 and +10º.) So once they were able to hold Pitch Attitude above 0, they stopped Electric Trim and Cutout the Stab Trim altogether. Of course, after that Electric Trim was out of the equation.

How about at the end of the flight, why did they only blip the Electric Trim? Possible theory:
1) Bjorn's analysis was that at 360 kts at the relatively low altitude, a tiny bit of trim input will result in a violent reaction.
2) Their Pitch Attitude was positive, so that was good enough for them.


Actually Bjorn's hypothesis is a combination of both 1 and 2. He proposed that after pressing the trim-up switch the pilot flying felt the desired response in not having to hold back the yoke with so much force, and thus paused to see how the plane would fly. After the pause lasted more than 5 seconds, then MCAS kicked in violently pushing the plane into a dive and causing the pilots to feel 0G and 'hit the ceiling'.

Notably Bjorn's conjecture is at odds with all the theorizing that the electric trim was ineffective. Bjorn clearly postulates that the electric trim was effective enough to induce the pilots to take a pause.

I have the highest respect for Bjorn but I think in that analysis he was really grasping for reasons why the pilots would not use the electric trim more after the dive started. There is no way the pilots would have been popped out of their seats into the ceiling because they would be strapped in. Certainly they would have had zero time and zero incentive to have unbuckled their harness after this hair-raising takeoff!

The fact the pilots did not respond to the final MCAS initiation leads me to believe they simply did not anticipate it. If you thought it might occur, and you knew MCAS can be active 5 seconds after the last manual electric trim command, you'd be flicking that trim tab every few seconds (at least until you get to a good trim quickly, then cut the power off again). My guess (which can never be proven, but I think makes more sense), is that the pilots didn't really understand the MCAS algorithm. Maybe they read the AD after Lion Air but didn't remember or weren't told about the 5 second rule, or maybe they thought MCAS wouldn't come back after one power cycle of the electric trim. Unfortunately, unless there was a conversation about MCAS that was not revealed in the preliminary report, we may never know.
 
flybucky
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 5:57 am

mzlin wrote:
Notably Bjorn's conjecture is at odds with all the theorizing that the electric trim was ineffective. Bjorn clearly postulates that the electric trim was effective enough to induce the pilots to take a pause.

Yes, I agree with the theory that Electric Trim was effective in both directions. Whereas Manual Wheel Trim was only possible Nose Down, not Nose Up (with elevators up).

I have the highest respect for Bjorn but I think in that analysis he was really grasping for reasons why the pilots would not use the electric trim more after the dive started. There is no way the pilots would have been popped out of their seats into the ceiling because they would be strapped in.

The fact the pilots did not respond to the final MCAS initiation leads me to believe they simply did not anticipate it. If you thought it might occur, and you knew MCAS can be active 5 seconds after the last manual electric trim command, you'd be flicking that trim tab every few seconds (at least until you get to a good trim quickly, then cut the power off again). My guess (which can never be proven, but I think makes more sense), is that the pilots didn't really understand the MCAS algorithm. Maybe they read the AD after Lion Air but didn't remember or weren't told about the 5 second rule, or maybe they thought MCAS wouldn't come back after one power cycle of the electric trim.

I also didn't think the pilots hit the ceiling like Bjorn's conjecture. I also think the final MCAS command caught them off guard, because they were distracted since they were in the midst of a 30º roll turn back to the airport. Then in less than 10 seconds, they were at Pitch Attitude -15º. At that point, they panicked, pulled the yokes as hard as they could to +15º, forgetting about the Electric Trim (or thinking it was too slow). But the plane was probably in an unrecoverable dive at that point (at least with the yoke).
 
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speedbored
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 6:47 am

barney captain wrote:
Sorry, but I see far more similarities than you obviously do. You seem to have already made up your mind that Boeing is solely to blame. I'm still waiting for the final report.

While it is true that there are some similarities, there are also some big differences:
    In the case of the A330, the fault only occurred "in a very rare and specific situation" so it is not unreasonable for this to not been foreseen as a negative test case.
    In the case of the MAX, the fault was caused by something that should have been foreseen as one of the most obvious negative test cases (single sensor failing high, low or off).
    In the case of the A330, the published procedure to recover from the fault worked correctly.
    In the case of the MAX, the published procedure was (a) ambiguous and (b) did not work.
IMO, one of these clearly involved negligence in both the test phase and the initial rectification phase; the other did not.
 
PStechPaul
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 6:51 am

Maybe a crazy idea, but would it be possible to rotate (roll) the plane such that it was flying upside down, which would allow it to gain altitude rather than dive? It probably would not have been able to save this plane, at least when it was in its final dive at low altitude, but wouldn't it invert the AoA and possibly allow the aircraft to climb, as well as perhaps reduce aerodynamic pressure on the control surfaces to allow manual adjustment to normal trim? Sorry if this is off-topic, but I like to think outside the box.
 
SimonL
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 7:41 am

The short answer to that is: It doesnt work that way.
 
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PixelFlight
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 8:33 am

speedbored wrote:
barney captain wrote:
Sorry, but I see far more similarities than you obviously do. You seem to have already made up your mind that Boeing is solely to blame. I'm still waiting for the final report.

While it is true that there are some similarities, there are also some big differences:
    In the case of the A330, the fault only occurred "in a very rare and specific situation" so it is not unreasonable for this to not been foreseen as a negative test case.
    In the case of the MAX, the fault was caused by something that should have been foreseen as one of the most obvious negative test cases (single sensor failing high, low or off).
    In the case of the A330, the published procedure to recover from the fault worked correctly.
    In the case of the MAX, the published procedure was (a) ambiguous and (b) did not work.
IMO, one of these clearly involved negligence in both the test phase and the initial rectification phase; the other did not.

Yep. the "very rare and specific situation" is a reference to the insane data that the faulty ADIRU generated. I must stress that still today, no one on this planet have ever published a plausible internal failure mode scenario that could possibly explain that ADIRU behavior. It's really not just a sensor offset or ripped sensors. No one have ever imagined before that an ADIRU could do this.

And I remain the very major difference between the A330 and the B737 MAX: safety assessment and certification review was found in good shape at Aibus and didn't try to hide information. The safety assessment and certification review criminal deficiency at Boeing is a reason good enough to ground the MAX: his certification is flawed at the procedural level.
:stirthepot: 737-8 MAX: "For all speeds higher than 220 Kts and trim set at a value of 2.5 units, the difficulity level of turning the manual trim wheel was level A (trim wheel not movable)." :stirthepot:
 
WIederling
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 8:36 am

OldAeroGuy wrote:
maint123 wrote:
The lion air crash can be termed a accident due to ignorance but the ethiopian crash is criminal neglect.
Boeing was too busy deflecting and blaming the crew and maintenance to take a serious look at their plane.
Anyone defending them should also be made accessories to their actions.
I will repeat, laws of physics are unforgiving. You can't fool them.


Very bold statements to make since the FAA/Boeing issued Emergency Air Worthiness Directive 2018-23-51 on November 7, 2018.

Which apparently was unsuitable for the task. ( due to pervasive disinterest? no idea )
( I find this pronounced lack of deep thinking sticking out all over MCAS and the resulting crashes irritating.)
Murphy is an optimist
 
VV
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 8:47 am

SomebodyInTLS wrote:
VV wrote:
If you switch them OFF it is then to fly the aircraft manually. And manual means the manual trim wheel (and the handle) without the help of any electrical power. That's my interpretation anyway.

So I am totally confused by the report.


I can't understand why when it's been pointed out dozens of times already.

3) they switched electric trim back on to try and correct the trim with "manual electric" again, but their trim corrections were less than those in the opposite direction by the re-connected MCAS


Are you certain about what you said? I am not.

Secondly, I do not understand why they didn't use the trim wheel. That's the real manual thing, isn't it?
There is a handle built on it. It is probably for something. It is certainly NOT a decoration.
 
VV
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 8:59 am

morrisond wrote:
SomebodyInTLS wrote:

I can't understand why when it's been pointed out dozens of times already.

1) they followed all of the memory items according to the AD issued after the Lion Air crash, however they had not fully corrected the MCAS trim with electric trim during this process (referred to as manual electric trim in the preliminary report)

2) at the end of this (trim switches cut off) they were physically trying to apply more manual trim using the wheels but were unable to presumably due to aerodynamic forces from the high speed (blowback)

3) they switched electric trim back on to try and correct the trim with "manual electric" again, but their trim corrections were less than those in the opposite direction by the re-connected MCAS

So the issue is why their manual electric trim was repeatedly less than sufficient - it now seems possible that the electric trim was also having issues with blowback.

Then the question is why they didn't reduce airspeed - well they didn't have pitch control and couldn't simply reduce thrust since they were very close to the ground


From the printed conversation it appears they only tried manual trim for 8 seconds and it was probably only one of them.

They were 8,000’ AGL - which while low is still sufficient altitude to try a few things - they were not 1,000’ AGL as speculated and repeated to me before this thread was started.


Quoting morrisond
From the printed conversation it appears they only tried manual trim for 8 seconds and it was probably only one of them.
end quote

From the chats in the preliminary report, it seems to be the case. There are two short attempts toward the end, but it is not clear for me whether the power switches were still OFF.

The last action of the MCAS just before the final plunge was most probably with the switches put back to ON. This is the part I do not understand at all.

If the power switch was turned ON, why didn't hey continue with the "manual" trim button on the control column.

The second source of my confusion I don't see any evidence the trim wheel was manually operated at any point, although I don't see any evidence of the contrary either.

Anyway, I am very confused by the report. So far, I can only say that while I agree that the MCAS system was not perfect, the consequence of its malfunction should have not been an accident if the appropriate pilot action was executed.

I am not saying it is the pilot's fault, I am just saying that MCAS failure should have been relatively benign if the pilot identifies the issue and take the appropriate actions.

I can understand the startle effect of the situation, just like the pilots on the AF447 were surprised by the situation and didn't take the right actions. Although the two accidents are completely different, I just want to point out that a system can fail and the consequence should have not been an accident if the pilots manage to identify the issue and take the appropriate actions.

I hope the above is not too confusing.
 
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speedbored
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 9:03 am

VV wrote:
SomebodyInTLS wrote:
VV wrote:
If you switch them OFF it is then to fly the aircraft manually. And manual means the manual trim wheel (and the handle) without the help of any electrical power. That's my interpretation anyway.

So I am totally confused by the report.


I can't understand why when it's been pointed out dozens of times already.

3) they switched electric trim back on to try and correct the trim with "manual electric" again, but their trim corrections were less than those in the opposite direction by the re-connected MCAS


Are you certain about what you said? I am not.

At this stage, none of us can be certain until we get to see the full CVR transcript or final report. But the available data and interim report certainly supports this hypothesis.

VV wrote:
Secondly, I do not understand why they didn't use the trim wheel. That's the real manual thing, isn't it?
There is a handle built on it. It is probably for something. It is certainly NOT a decoration.

Are you certain that they didn't try to do that? Again, the available evidence suggests that they did but were unable to make it work.
 
MigPilot
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 9:05 am

VV wrote:
Secondly, I do not understand why they didn't use the trim wheel. That's the real manual thing, isn't it?
There is a handle built on it. It is probably for something. It is certainly NOT a decoration.


Who said they didn't try?

Image
 
xmp125a
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 9:51 am

PStechPaul wrote:
Maybe a crazy idea, but would it be possible to rotate (roll) the plane such that it was flying upside down, which would allow it to gain altitude rather than dive? It probably would not have been able to save this plane, at least when it was in its final dive at low altitude, but wouldn't it invert the AoA and possibly allow the aircraft to climb, as well as perhaps reduce aerodynamic pressure on the control surfaces to allow manual adjustment to normal trim? Sorry if this is off-topic, but I like to think outside the box.


No. The wing surfaces in any commercial aircraft are shaped in the way that they create the lift upwards (for the reasons of efficiency). This thing would be possible only in fighter planes with disproportionaly powerful engines compared to the airliners.
 
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scbriml
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 9:54 am

VV wrote:
Secondly, I do not understand why they didn't use the trim wheel. That's the real manual thing, isn't it?
There is a handle built on it. It is probably for something. It is certainly NOT a decoration.


We don't know that they didn't.

Even with that convenient handle thingamajig, it would appear to be quite difficult to turn in some circumstances and especially while simultaneously trying to pull the yoke back with all your might.

MigPilot wrote:
Who said they didn't try?

Image
Time flies like an arrow. Fruit flies like a banana!
There are 10 types of people in the World - those that understand binary and those that don't.
 
flybucky
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 9:59 am

MigPilot wrote:
https://media.giphy.com/media/TgbF6sloqHQxGcxJTe/giphy.gif

Great gif. What is the source video for it? Is that the MentourPilot video that was taken down? Or a different video?
 
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PixelFlight
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 10:00 am

MigPilot wrote:
Who said they didn't try?
Image

Dam. I have see the Mentour Pilot where he explain that moment and why it removed that video, but I didn't realized that there tried so hard.
For those that still blame the pilots, I hope there understand now that while one pilot do this, the other have to use all his force on the column. Add the alarms and the stick shaker to the confusion.
Last edited by PixelFlight on Sat Apr 13, 2019 10:21 am, edited 1 time in total.
:stirthepot: 737-8 MAX: "For all speeds higher than 220 Kts and trim set at a value of 2.5 units, the difficulity level of turning the manual trim wheel was level A (trim wheel not movable)." :stirthepot:
 
flybucky
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 10:14 am

VV wrote:
If the power switch was turned ON, why didn't hey continue with the "manual" trim button on the control column.

We don't know for sure, but Bjorn's theory is that at high speed (360 kts) and relatively high air density (~10,000 ft AMSL), a small input to the Electric Trim would have caused a severe reaction, so that's why they only blipped the Electric Trim briefly. Also, with so much distractions in the cockpit, they were probably just focused on keeping the Pitch Attitude above 0. And since they accomplished that, they backed off the Electric Trim. (Do read Bjorn's analysis at https://leehamnews.com/2019/04/05/bjorn ... -analysis/ . It has a lot of great insights.)

VV wrote:
The second source of my confusion I don't see any evidence the trim wheel was manually operated at any point, although I don't see any evidence of the contrary either.

The most likely reason we don't see evidence of the trim wheel is because the stabilizer load at the jackscrew prevented manual wheel trim in the nose up direction. However, the Pitch Trim gradually drifted nose down from 2.3 to 2.1 units over 2.5 minutes while the Stab Trim was Cutout. That could be evidence of attempted manual wheel trim failing to budge in the Nose Up direction, but causing it to drift Nose Down as the pilots jiggled the manual trim wheel.
 
MigPilot
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 10:25 am

flybucky wrote:
MigPilot wrote:
https://media.giphy.com/media/TgbF6sloqHQxGcxJTe/giphy.gif

Great gif. What is the source video for it? Is that the MentourPilot video that was taken down? Or a different video?


Yes, it's from the video Mentour Pilot has to take down for 'reasons'.

Not generated by me BTW. Just reposted from pprune.
 
patplan
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 10:35 am

VV wrote:
SomebodyInTLS wrote:
VV wrote:
If you switch them OFF it is then to fly the aircraft manually. And manual means the manual trim wheel (and the handle) without the help of any electrical power. That's my interpretation anyway.

So I am totally confused by the report.


I can't understand why when it's been pointed out dozens of times already.

3) they switched electric trim back on to try and correct the trim with "manual electric" again, but their trim corrections were less than those in the opposite direction by the re-connected MCAS


Are you certain about what you said? I am not.

Secondly, I do not understand why they didn't use the trim wheel. That's the real manual thing, isn't it?
There is a handle built on it. It is probably for something. It is certainly NOT a decoration.


The reason?

Well, at a very high speed, this thing actually happens...

Image
 
patplan
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 10:44 am

Double posted... My Apology.
 
smartplane
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 10:56 am

MSPNWA wrote:
mjoelnir wrote:
A crash is a fact. Two crashes are two facts. Hesitation kills.

Calling a frame safe, after a crash, should be based on facts.

Goes back to what I said long ago in these threads. Safety isn't based on raw stats. The aviation industry is incredibly safe because stats aren't the driver of improvements.

The aviation industry WAS incredibly safe. With the MAX, Boeing has reversed two decades of improvements, both the stats and reality.
 
VV
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 11:02 am

flybucky wrote:
MigPilot wrote:
https://media.giphy.com/media/TgbF6sloqHQxGcxJTe/giphy.gif

Great gif. What is the source video for it? Is that the MentourPilot video that was taken down? Or a different video?



I have the feeling the video is not serious.
 
morrisond
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 11:11 am

flybucky wrote:
VV wrote:
If the power switch was turned ON, why didn't hey continue with the "manual" trim button on the control column.

We don't know for sure, but Bjorn's theory is that at high speed (360 kts) and relatively high air density (~10,000 ft AMSL), a small input to the Electric Trim would have caused a severe reaction, so that's why they only blipped the Electric Trim briefly. Also, with so much distractions in the cockpit, they were probably just focused on keeping the Pitch Attitude above 0. And since they accomplished that, they backed off the Electric Trim. (Do read Bjorn's analysis at https://leehamnews.com/2019/04/05/bjorn ... -analysis/ . It has a lot of great insights.)

VV wrote:
The second source of my confusion I don't see any evidence the trim wheel was manually operated at any point, although I don't see any evidence of the contrary either.

The most likely reason we don't see evidence of the trim wheel is because the stabilizer load at the jackscrew prevented manual wheel trim in the nose up direction. However, the Pitch Trim gradually drifted nose down from 2.3 to 2.1 units over 2.5 minutes while the Stab Trim was Cutout. That could be evidence of attempted manual wheel trim failing to budge in the Nose Up direction, but causing it to drift Nose Down as the pilots jiggled the manual trim wheel.


That is entirely possible - however it could also be excessive Aerodynamic loads due to being over Vmo (A.K.A Vne (Velocity Never Exceed - the plane is not designed to handle those loads) on an incorrectly positioned Horizontal stabilizer causing it to go from 2.3 to 2.1 - they were wrenching pretty hard on the Control Columns and the deflection of the elevators was not constant - loading and unloading the Horizontal stabilizer (more than it already was) - it's not inconceivable that at over Vmo damage could be done to the Horizontal Stabilizer (control surface or Jack screw) causing the reading to go from 2.3 to 2.1.

You would have thought that if the were trying the manual trim wheel for minutes the Pre-lim report would have mentioned it.

Impossible to know.
 
morrisond
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 11:23 am

Double post
Last edited by morrisond on Sat Apr 13, 2019 11:35 am, edited 1 time in total.
 
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scbriml
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 11:28 am

VV wrote:
I have the feeling the video is not serious.


Why?
Time flies like an arrow. Fruit flies like a banana!
There are 10 types of people in the World - those that understand binary and those that don't.
 
morrisond
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 11:29 am

PW100 wrote:
XRAYretired wrote:
OldAeroGuy wrote:
Very bold statements to make since the FAA/Boeing issued Emergency Air Worthiness Directive 2018-23-51 on November 7, 2018.

That my be so, and may prevent any 'charges' being levelled. but, also worth mentioning that the Boeing procedure in the AD did not prevent a catestrophic outcome on the one occasion it was necessary.

In particular, it did not mandate re-setting trim to 'neutral' prior to the cut-out action, which perhaps it should have and secondly, it made no mention of Flaps . . .
Either of these may have prevented the catastrophic outcome.

Ray


I'm not sure if the trimming instruction would have changed anything with respect to the ET accident: the crew did do just that: uptrimming before cutting out electric trimming. In fact, the released FDR graphs shows the largest amount of uptrimming was right before the electric trimming was cut.

The uptrim just did not reach the "neutral" condition. And we do not know why that is. Perhaps that was an incompetent crew, as some repeatingly suggest as their favourite explanation (and then mumbling on about declining pilot standards worldwide . . . ).

It could be something else, something outside crew control. If the crew could not get more uptrim out of the electric (or manual crank) trimming, then a different procedure by Boeing (and AD mandated) would not have changed a thing. I find it believable that this could be related to Boeing delaying the release of "the MCAS fix".


That is entirely possible that something was not allowing the Horizontal stabilizer to get past 2.3. It's hard to imagine what it is - but it is possible.

At normal speeds that would not have been an issue as the pilots would have had enough elevator authority and would have been able to apply enough force with the control columns to offset it.
 
flybucky
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 11:31 am

VV wrote:
I have the feeling the video is not serious.

I know that without context, the video seems like a joke due to the jerky gif with captions in the style of a meme video. But I can assure you the original was a very serious video by a reputable 737 pilot called Mentour Pilot (his YouTube handle).

Here is Bjorn Fehrm referencing Mentour Pilot's video: https://leehamnews.com/2019/04/03/et302 ... stop-mcas/

Seattle Times referencing Mentour Pilot's video: https://www.seattletimes.com/business/b ... an-flight/

This is Mentour Pilot's explanation of why he took down the video: https://youtu.be/q17vykscK0w

Full transcript of the video
 
morrisond
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 11:31 am

smartplane wrote:
MSPNWA wrote:
mjoelnir wrote:
A crash is a fact. Two crashes are two facts. Hesitation kills.

Calling a frame safe, after a crash, should be based on facts.

Goes back to what I said long ago in these threads. Safety isn't based on raw stats. The aviation industry is incredibly safe because stats aren't the driver of improvements.

The aviation industry WAS incredibly safe. With the MAX, Boeing has reversed two decades of improvements, both the stats and reality.


It still is - I would have to bet that if you add up all the people who travelled safely on a MAX there survival rate is still better than a car.
 
morrisond
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 11:34 am

morrisond wrote:
PW100 wrote:
morrisond wrote:
I'm not suggesting that the MAX shouldn't be grounded - it should. But declining worldwide training standards (MD80TTail shared some good stories on lack of training in North America as well) shouldn't be ignored either.

The reason the two Airbus incidents turned out with no loss of life were well trained crew - not because the A330 was FBW.


Yes, the worldwide declining standards mainly seem to affect 737 MAX aircraft.
Perhaps Boeing should start informing pilots about the hidden systems, and manual back-up systems not working at some part of the flight envelope.

It is becoming quite tiring reading about the declining pilot standards (outside the US of A of course), in relation to the deaths of 350 people, when the root causes of both accidents are probably to be found mainly inside the US of A.


Do you have problems reading? Did I say outside the US? I said Worldwide and I specifically mentioned that training is deficient in North America as well.

Are you comfortable with the state of training worldwide?

It seems to me as though the last number of major accidents could have turned out better if better training existed. All the people bashing on Boeing conveniently forget that Airbus is establishing schools worldwide as they think Training Standards aren't what they should be.

It has not been established 100% that the backup systems did not work. There is some doubt that they were even tried.
 
PcarSBA
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 11:45 am

I read Björns report. I am still trying to understand why they did not back off the thrust at some point.

If I understand correctly the building IAS with its increasing aerodynamic loads narrowed the envelope more and more to where

- manual trim (spinning the wheel) became increasingly difficult to the point of being impossible
- MCAS input and/or trim switch inputs on the stabilizer with cut-off switches engaged resulted in violent G-forces
- flaps re-engage was out off the question due to high speed
- blow-back reduced elevator authority

How many indicators did they have to realize (in their high-stress situation) they went beyond Vmo while thrust was still at almost 100%.
 
morrisond
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 12:09 pm

PcarSBA wrote:
I read Björns report. I am still trying to understand why they did not back off the thrust at some point.

If I understand correctly the building IAS with its increasing aerodynamic loads narrowed the envelope more and more to where

- manual trim (spinning the wheel) became increasingly difficult to the point of being impossible
- MCAS input and/or trim switch inputs on the stabilizer with cut-off switches engaged resulted in violent G-forces
- flaps re-engage was out off the question due to high speed
- blow-back reduced elevator authority

How many indicators did they have to realize (in their high-stress situation) they went beyond Vmo while thrust was still at almost 100%.


A lot - FO Instruments - Back Up instruments - Overspeed Warning (which they might have chose to ignore as various other horns were going off as well and they didn't seem to be correct.
 
MigPilot
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 12:22 pm

VV wrote:
flybucky wrote:
MigPilot wrote:
https://media.giphy.com/media/TgbF6sloqHQxGcxJTe/giphy.gif

Great gif. What is the source video for it? Is that the MentourPilot video that was taken down? Or a different video?



I have the feeling the video is not serious.


Considering every copy of the full video is deleted within hours, somebody seems to have a quite serious intend to remove it from the net.

(if one know how to google - and is quick enough, it still can be found tho)
 
patplan
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Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 12:22 pm

VV wrote:
flybucky wrote:
MigPilot wrote:
https://media.giphy.com/media/TgbF6sloqHQxGcxJTe/giphy.gif

Great gif. What is the source video for it? Is that the MentourPilot video that was taken down? Or a different video?



I have the feeling the video is not serious.


Do you really want to get serious..??

Do watch this in its entirety...

- https://youtu.be/DJ6P3f5uCR4

Full transcript...
00:11:24,900 --> 00:11:25,700
We have an IAS disagree.

00:11:25,900 --> 00:11:27,200
So, "IAS DISAGREE MEMORY ITEMS".

00:11:27,500 --> 00:11:29,500
Autopilot - if engaged, disengage.

00:11:29,500 --> 00:11:30,100
Disengaged!

00:11:30,300 --> 00:11:32,500
Autothrottle - if engaged, disengage.

00:11:32,600 --> 00:11:33,100
Disengaged!

7
00:11:33,300 --> 00:11:34,500
Flight directors - Both Off.

00:11:34,600 --> 00:11:40,100
With flaps up, established a flight
path of 4 degrees and 75% N1.

00:11:40,500 --> 00:11:44,500
Flaps up, 75% N1.

00:11:47,300 --> 00:11:48,900
We have 77, 76,...

00:11:49,300 --> 00:11:50,600
A little bit less...

00:11:53,700 --> 00:11:53,500
4 degrees.

00:11:53,700 --> 00:11:55,500
4 degrees.

00:11:55,700 --> 00:11:58,000
So I am trying to establish
this now.

00:11:58,200 --> 00:11:59,100
Check.

00:12:02,700 --> 00:12:04,700
We are descending...

00:12:05,100 --> 00:12:08,200
We probably... Are you feeling
troubled with...

00:12:08,500 --> 00:12:10,100
Any trouble with the flight
control?

00:12:10,300 --> 00:12:12,500
Yeah, it's...it's...
I'm trying to pre-trim it but...

00:12:12,700 --> 00:12:14,500
It continues to trim against me
when I'm trimming

00:12:15,700 --> 00:12:16,900
So state the malfunction, please.

00:12:17,100 --> 00:12:18,500
Yeah, this doesn't look right,
uh...

00:12:18,700 --> 00:12:20,100
Looks like, uh...

00:12:20,300 --> 00:12:22,500
How do you feel the stabilizer,
the trim system?

00:12:22,700 --> 00:12:23,800
Can you control it?

00:12:24,100 --> 00:12:26,600
I'm trimming it. It is
responding but...

00:12:27,200 --> 00:12:28,500
It's a runaway stabilizer,
if you agree?

00:12:28,600 --> 00:12:31,500
For everytime that I trim backward,
it keeps trimming forward.

00:12:31,600 --> 00:12:34,500
It's trimming forward. Yeah,
it's runaway stabilizer.

00:12:34,600 --> 00:12:36,500
So, "RUNAWAY STABILIZER MEMORY
ITEMS"....

00:12:36,700 --> 00:12:39,500
And, I'm trying to keep this
thing at 4 degrees.

00:12:39,700 --> 00:12:40,500
Control Column - Hold firmly.

00:12:40,700 --> 00:12:41,500
Oh..., I am...

00:12:41,700 --> 00:12:44,000
Autopilot - if engaged, disengage.

00:12:44,200 --> 00:12:44,900
It is disengaged.

00:12:45,200 --> 00:12:47,500
Autothrottle - if engaged, disengage.

00:12:47,700 --> 00:12:50,500
It's..., if you can disengage it for
me, make sure that it's disengaged.

00:12:50,700 --> 00:12:51,500
It's disengaged.

00:12:52,000 --> 00:12:54,600
And, do you feel that the
failure stop?

00:12:55,000 --> 00:12:56,200
Negative?

00:12:56,400 --> 00:12:57,200
No, it's still moving!

00:12:57,500 --> 00:13:01,100
Stab trim cutoff switches to cutoff.

00:13:02,700 --> 00:13:05,100
OK. It stops. It looks like it stops.

00:13:05,500 --> 00:13:08,800
As you can see now, I'm using almost
a full back pressure here.

00:13:09,200 --> 00:13:10,000
Yeah, exactly.

00:13:10,300 --> 00:13:12,000
How many degrees nose down?

00:13:13,700 --> 00:13:14,600
We have 4 units nose down now

00:13:15,100 --> 00:13:16,500
4 units nose down?

00:13:18,500 --> 00:13:19,200
Yeah.

00:13:19,700 --> 00:13:20,500
OK, I'm struggling.

00:13:20,700 --> 00:13:24,900
I'm actually using almost my full force
to keep the aircraft level here.

00:13:25,200 --> 00:13:26,100
Do you want me to help you?

00:13:26,300 --> 00:13:27,800
What I would like to do...

00:13:28,400 --> 00:13:30,500
Just for the sake of exercise,
can you trim this forward?

00:13:30,700 --> 00:13:33,000
See if we can reach even zero
nose down.

00:13:33,300 --> 00:13:35,500
And see if I can even hold it.

00:13:37,400 --> 00:13:40,200
So, now we are doing this just
as an exercise, guys!

00:13:40,200 --> 00:13:43,000
Do not try this at home.

00:13:48,700 --> 00:13:49,500
We're at 300 knots now.

00:13:49,700 --> 00:13:50,800
I'm fighting.

00:13:51,700 --> 00:13:54,500
I'm struggling to keep this aircraft flying.

00:13:56,900 --> 00:13:58,800
My God!

00:13:59,000 --> 00:13:59,800
Yeah, the thing is...

00:13:59,900 --> 00:14:04,200
With higher speed the force on the
stabilizer will be higher and higher as well.

00:14:04,500 --> 00:14:07,000
So it becomes almost impossible to move it.

00:14:11,300 --> 00:14:13,900
So now, we are at about 3 degrees.

00:14:14,200 --> 00:14:15,000
Yeah..

00:14:15,700 --> 00:14:18,500
We're still about 3 degrees away
from full nose down trim.

00:14:18,900 --> 00:14:21,000
And I am using everything that
I have.

00:14:22,400 --> 00:14:23,200
My God!

00:14:26,700 --> 00:14:27,800
And, this is realistic guys.

00:14:28,200 --> 00:14:33,200
This is how much of effort it'd take to
trim the stabilizer at this kind of speed.

00:14:36,300 --> 00:14:37,000
Umph...

00:14:38,700 --> 00:14:40,500
I'm just in control of it, though.

00:14:40,700 --> 00:14:42,400
But it is getting harder and harder.

00:14:43,200 --> 00:14:46,100
And remember we are still
2.5 degrees away...

00:14:49,400 --> 00:14:50,500
My God!

00:14:50,700 --> 00:14:52,200
It's not possible, is it?

00:14:53,200 --> 00:14:54,500
All right, we stop at that.

00:14:55,200 --> 00:14:59,200
The reason we have to trim this
manually is because...

00:14:59,400 --> 00:15:02,200
the normal trim system wouldn't
do this, ok.

00:15:02,500 --> 00:15:06,100
It would require manual trim to
get it away from this.

00:15:07,900 --> 00:15:08,500
That's fine.

00:15:09,200 --> 00:15:10,200
Trim it backward.

00:15:10,400 --> 00:15:11,800
Trim it backward as you can.

00:15:14,500 --> 00:15:19,900
Oh my God! I couldn't...

00:15:20,300 --> 00:15:20,900
OK.

88
00:15:21,500 --> 00:15:23,400
Uh...

00:15:24,100 --> 00:15:25,900
Juan, press the red button!

00:15:26,200 --> 00:15:27,400
Press the red button now.

00:15:28,600 --> 00:15:30,600
This is at 340 knots.

00:15:31,000 --> 00:15:33,300
And the trim is at...

00:15:34,000 --> 00:15:36,700
It's still at almost 2.5 degrees
something...

00:15:36,900 --> 00:15:37,500
Yeah, 2.5 degrees.
 
o0OOO0oChris
Posts: 114
Joined: Sun May 13, 2012 10:27 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 12:44 pm

Wow, that video clears up some things:
- At 2,5°, the pilot has to use all his force to control pitch. And he doesn`t even have the feel system , thinking they are approaching stall, adding a lot of force on top of that. So in the MCAS situation, pitch would not be controllable from 2.5° ND trim for one pilot.
- As the pilot has to use all his force to control the elevator, he can`t help the copilot to trimm back down.
- Below 2,5° ND, the copilot has to help the pilot to controll the elevator - but then he can`t trim it back up again.
- So they have to decide to run the stabilizer together or the elevator. Not a choice that leads to a good outcome below 5000 feet AGL
- It must be extremely frightening and shocking for a pilot to realize that the control is fading away from him slowely but shurely. Getting panicked is a high probablility in that environment and that is really bad for the decision making process. They didn`t have a red button to push.
- Both Pilots are male, tall and look fit. How would a small female pilot do in this situation? Are there limits on physical strength a pilot has to have to get type rated?
- It took quite a while using good crm and communication between the pilots to do the checklists and confirm the runaway trim before they cut out.
 
VV
Posts: 1841
Joined: Sat Feb 13, 2016 1:03 pm

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 12:54 pm

scbriml wrote:
VV wrote:
I have the feeling the video is not serious.


Why?


Why?

Because none of the two actors looks towards the instruments not toward the handle.

A normal human being working in a cockpit would have been looking at what they are doing instead of looking elsewhere..
 
User avatar
speedbored
Posts: 2230
Joined: Fri Jul 19, 2013 5:14 am

Re: Ethiopian Airlines 737MAX crashes enroute to Nairobi

Sat Apr 13, 2019 1:02 pm

VV wrote:
scbriml wrote:
VV wrote:
I have the feeling the video is not serious.


Why?


Why?

Because none of the two actors looks towards the instruments not toward the handle.

A normal human being working in a cockpit would have been looking at what they are doing instead of looking elsewhere..

They literally spend the entire time looking at either what they are doing, or the person they are communicating with.

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