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Report claims pilots of the Ethiopian MAX 8 followed emergency procedures accordingly

Addis Ababa - The new insights from the investigation of the Ethiopian 737 MAX 8 crash could cause considerable problems for Boeing. ( Más...

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Warren Craycroft 21
I design and validate safety-significant software systems for a living. I've seen some useful observations in this forum over the past few weeks, especially from the pilots and system designers. And of course some chaff to be ignored.

As the investigation proceeds, there are a couple of rookie mistakes to watch out for, as even experts sometimes fall into these traps:
1) When analyzing actions and decisions of people over time leading up to an accident, it is unfair to apply your present "perfect" knowledge of what happened. You must "walk the timeline" shoulder to shoulder with those people and assess their actions and decisions with what they knew at that moment in time. Doing the latter can uncover root-cause defects that might otherwise remain undetected.
2) Be careful of firm, unyielding comments about how the systems worked leading up to the accident; e.g., "when you flip this switch, this IS what happened". Everything in the system behavior should now be suspect until the root causes have been identified and fixed; design specifications, test procedures, training, and user documentation has been updated to accommodate new knowledge; and the entire avionics system has been re-validated, i.e., has been shown to meet all design specifications by generating objective evidence from testing, simulations, inspections, and reviews.
lecompte2 -9
Great point, we should go all the way back to Boeing's decision to create an airplane the cheapest way possible that appears to be modern with new technology. But in fact it is a collection of a few new parts and mostly old parts made to fit together. And then we should take a look at how this plane made it through certification and made it to the airport accepted by the airlines and their engineers. Then we will know how this got here and more important where we must go now with it, if we want passengers to fly in it.
24000 hours flying 727,757,767,MD 11,DC9,DC8,DC7,DC6,C130, CV440 and I've never been on an airplane that even remotely approached an aerodynamic stall, except on training flights. You would have to be comatose to not feel it in your seat and other cues. Attitudes are so extreme as to be unmistakeable. Only exceptions are T-tailed airplanes that do need power assist on down elevator, but never by trimming stabilizer. Even primary flight students learn stall recovery before solo! Too much unneeded engineering to fix a problem that does not exist. Engineering caused these accidents, not the pilots.
Tim Kerssen 5
I had been wondering about the need for stall-prevention. Seems that for a very infrequent event, there might be a better way than a blind 'push the nose down' approach. Though, as I recall, the Air France incident resulted from the pilot stalling a perfectly good aircraft right into the drink despite all the stall warnings working well. What really bothers me though is this gorilla system that wrests control from the humans acts decisively based on a single input. I designed avionics in the space industry and we never accepted single point of failure in avionics leading to mission failure unless there was no alternative. Commercial aviation should be at least as conservative. Obviously, since Boeing sells an optional feature for detecting disagreement from two AOA sensors, they could use both as inputs to MCAS. I'm guessing that they could also incorporate airspeed, vertical speed, pitch sensing, and um, I don't know, how about physical principles. In the Ethiopian crash, the AOA sensor showed a near-step function between 11 and >70 degrees up. Physics tells me that this cannot happen and something is broken. Likewise, if the two sensors don't agree, there's a problem. Also, if the aircraft is beginning to stall, the up angle will be accompanied by negative vertical speed derivative. There are many associations which can be checked to verify the actual condition without having to rely on a single sensor. If you're going to design a "safety" device that can crash the plane, at the very least, make sure it uses all available information before doing so.
lecompte2 17
You people have to understand that the trim activates the horizontal stabilizer which is twice the size of the elevator controlled by the pilot so the pilot cannot overpower the trim when it is active. Now if the aircraft is in a high speed dive after the MCAS has run the trim to full nose down or close to it and is selected off by the pilot, the aerodynamic forces on the stabilizer (trim) are so strong that the pilot cannot override them in manual mode, this probably why they attempted to restart the electric trim in desperation to regain control in this short time event.
JetMech24 4
A couple other things to add: 1) The horizontal stabs have a "neutral shift" mechanism to the elevators, what this does is move the elevators with the stabs to assist in the pitch trimming, so if the stabs are at full nose down, the elevators are also slightly pitched nose down. 2) The design of the 737 makes the aircraft nose down the faster it is traveling. The 737 has a elevator "mach trim" system that will slightly pitch up the elevators' neutral position to compensate for the nose down tendency at around 250 knots. To summarize, the pilots are fighting a maxed out stab trim which is possibly impossible to roll back by hand cranking (which also would take a long time to do even if it is possible to move), they are pulling back on the yoke as much as possible but not getting the full movement of the elevators due to the neutral shift mechanism, and fighting the natural tendency of the 737 to nose down at high speeds, all within a very short period of time. I, for one, do not blame them in their desperation for turning the cutouts back on in hopes of getting assistance from the electric motors.
Tom Trainor 2
I have concluded that both of these 73M accidents were David (the elevator & pilots)) vs. Goliath (the stabilizer & MCAS). Goliath won before David could get the rock out of his pocket. It was a horrendous deadline in the truest sense. I wish the Ethiopians would let the NTSB 'take over'. (I first noticed the 'adjustable' stabilizer on another 'modern' airliner while looking out the window at another plane (a 757 I think) years ago. I was astonished - Holy S*** - the whole d**n assembly goes up and down!).
Remember the rudder nightmare? That also knocked two 737s out of the sky and killed many helpless people. The NTSB eventually found it.
btweston 8
This is disturbing. Teething problems my taint.
Kobe Hunte -5
agreed. what if there is something major wrong with the frame of the plane?? What would happen then?
Shenghao Han 3
Structural problems should be the last thing you suspect on a somewhat newly built plane without any prior incidents to that specific aircraft...
737 isn't Boeing's first design, nor it will be the last.
The procedures are for them to turn off stab trim for the remainder of the flight. When the problem occurred they turned off stab trim and turned it back on a little while later. Clearly NOT following proper procedure.
Please someone who is rated in the 737 answer this.

I see on the control pedestal that there are two trim lockout switches. One is marked "Autopilot" the other "Main Elect".

If the one marked "Autopilot" is cut out on its own, does that disable MCAS, but allow the pilots to use the electric trim?
hornet135 3
From the sources I’ve read, only the main electrical trim cutout disables MCAS. In other words, if you have to disable MCAS, you’re going to be hand cranking the trim after the cutout is switched.
Andre Melgaço 2
That is stressed on Boeing Bulletin - nov, 6th 2018. You just cut it out.
Luigi Torreti 2
Who projected, approved and released the procedure "created" to bypass MCAS decision...?
Rick Crose 2
I feel this goes much farther than software or design. Two things to note. (1) is the lack of fundamental flying skills. Today's Part 141 pilot mills (puppy mills) turn out certificate holders (notice I didn't say pilots) that have great push button skills but lack in basic fundamental flying skills. The same with 3rd world countries (2) I cannot believe that with the amount of flying done in the USA (far more than all other countries combined) that this same problem has not been experienced with American flag carrier flight crews. I am sure it has been many times but we never hear about because it didn't result in a crash. They write it up, it gets fixed and they fly again. We all know that if the trim or whatever device is not working, you pull the circuit breaker and you don't try to engage it again. I know nothing about the B737 max but I would ride on that aircraft anytime as long as it is with an American flag carrier and not a 3rd world country where the pilot's depend so much on automated systems. This is why you have pilots in the first place and when basic flying skills go away, you have nothing to lean on except the automation or instrument indications which sometimes fail (Asiana, Air France, Ethiopian...etc). The day of the fully automated flight deck is the day I no longer fly or ride in an aircraft.
rugomol 3
Pilots at the controls of the Boeing Co. 737 MAX that crashed in March in Ethiopia initially followed emergency procedures laid out by the plane maker but still failed to recover control of the jet, according to people briefed on the probe’s preliminary findings.
Andre Melgaço 1
The only thing to be based upon is
Appendices can be intuitively interpreted. Maintenance Log is very interesting!
Fritz Steiner 1
It's said that the only really stupid question is the one that didn't get asked ... so I'm asking. My question stems from the statements about using the manual crank to correct the trim. I gather that in the 737-800's (and maybe the whole 737 family) the entire elevator then must be what's being trimmed rather than much smaller trim tabs.

Is this correct?

If so, it seems (to me) that the expectation that the manual crank could EVER be fast enough to correct the trim in an emergency was far-fetched and unreasonable.
The hand crank adjust horizontal stabilizer trim, not elevator trim.
Fritz Steiner 1
David, please correct me if I'm wrong, but don't the elevators control the VERTICAL attitude? In both crashes I believe the MCAS initiated screw drive was found to be in the FULL DOWN position -- as were the airplanes' nose when they hit the earth.
The horizontal stab is trimmed for zero pitch to reduce pilot input on the elevators to reduce fatigue.

Whether the autopilot, mcas, or the pilots control wheel switches command a stab pitch change, the signal goes to an electric motor mounted on the stab jack screw. The crank handle wheels are connected to the stab jack screw by cables. So when the electric motor moves the stab, it backfeeds the cables and turns the crank handle wheels. That’s why they move when no one is touching them.
George Cottay 1
As the story develops I'm waiting to hear if pilots will get simulator hours before the MAX goes back into service? And, if not, how many will pass on flying it.
Ken Keighron 1
Silent Bob 0
Holy shit talk about dishonest headlines. This is the very first paragraph from the article: According to the Wall Street Journal, the pilots of the crashed Ethiopian 737 MAX 8 acted exactly according to the emergency procedures written on the checklists and then deviated from them.

So the trim is misbehaving. They turn it off according to procedure (good). Then they decide that's not good enough apparently and turn it back on (bad). And somehow the headline is they "followed emergency procedures accordingly"?! Bullshit, no where in the QRC/QRH does it ever say to turn the trim back on after it's been disabled.
LW P 11
They turned it back on because manually using the trim wheels wasn't bringing the nose up fast enough. It was a last-ditch effort to pull out of the dive.
lecompte2 3
If you are pointed at the earth at a 40° angle and you are trying to pull back with all your might on the control column and at the same time trying to trim back manually with the trim wheel but your speed is approaching 500 knots and you cannot move the wheel because of aerodynamic forces on the stabilizer. Then you will try anything to get that nose to come up.
Highflyer1950 4
If you have ever flown a ‘37 or ‘27 in manual trim you know how many turns of the trim wheel it takes just to even out a little control pressure? Can you imagine how many times you would have to crank that wheel if the aircraft was grossly out of trim? After about 15 turns and you still can’t feel much might be inclined to turn the Trim cutout switches back on especially if your hands on flying experience in type is low and you don’t know any different. Interesting to note that the airlines are already blaming the manufacturer deflecting any lawsuits against themselves in order to save face? Sure wish the NTSB was in charge.
Bill Harris 3
Seattle Times has a story out suggesting that with the stab at the max deflected position, aerodynamic forces on the trim system might have been more than could be counteracted at the jack screw by using the trim wheels, unless the pilots followed a control maneuvers not detailed in the current training manuals.
What does flying a '37 or '27 have to do with dishonest reporting?
Daniel Bailey 2
Exactly! I just read the entire article. The headline is just an attention grabber. Reading the entire (poorly written) article shows that if you have to deactivate a system because of a fault, don’t turn it back on!

If your trim system is running away, you don’t turn it back on because it’s hard to manually trim it. This is more an indictment of pilot training and experience than of Boeing. However, it is true that the 737 design has been pushed to its limit by this. Time for a ground up new design for both Mid and Large narrowbody aircraft.
Tom Trainor 2
Hi Daniel - I think you (and many others) will find this very well-written (well, I think so) article by Jason Perlow (ZDNET/Tech Broiler) very interesting:
Colette Miller 4
Very good article. Thought provoking. I'm sure there is plenty of blame tog o around.
As a pilot of light aircraft for 50 years, I have noticed that most accidents don't have one cause, they have many small causes that add up to disaster.

Furthermore in my years flying older aircraft, I have seen many retrofits that worked, and many that did not, sometimes with disastrous results.

With all of our machines and gadgets, it is good to remember that, at some point, we can no longer patch the patches or weld the welds. We need to start with a new and fresh design if we want a smooth running machine.
btweston 0
You didn’t read the rest. They disabled it, if turned back on by itself, then they disabled it a few more times, it came back on, then they went into figure-it-out mode until it hit the ground.

What would you have done, General Yeager?
YOU didn't read the rest.

You can be either informed, uninformed, or misinformed. Reading the rest of that article without checking the source makes you the latter.
Torsten Hoff 1
There is conflicting information on whether the MCAS was intentionally turned back on, or automatically.
Daniel Bailey 4
If the Elevator trim switches are in the “cutout” position, the system will be unable to move the elevators even if it was trying, so I’m not sure how it could “re-activate”. But, I think I’ll avoid all of these poorly researched and mis-leadingly headline articles until the official analysis of the accident is published.
btweston -3
I question your credibility.
Wouldn't you think if the pilot turned the MCAS off it should have stayed off?
Holy shit is right. This is so over the top that we aren't even discussing how bad the WSJ piece is all by itself.

Now, believe it or not I've been wrong before, but I'm pretty sure "initially following procedure" is the exact same thing as not following procedure. Holy shit.

Dad: Did you break the window?
Son: Initially, no, I did not.
Dad: Your mother and I are so proud of you.

People are accepting this. We are so screwed.
David Beattie 0
WSJ is owned by Fox News. I wouldn’t trust them!
Brian Neuman 1
Misleading headline at best.
Charles Adams 1
I never though that I would witness the fall of a giant like this is starting to look like. Of course I am probably overreacting but if not a fall then a bloody nose and two black eyes. Now the Airbus sales force will have D Day in reverse. They will be sending ships and landing crafts full of men and women dressed in three piece suits armed with discount offers to any customer they can pry away from Boeing. Hell, they might even drop them out of DC-3s (C-47s) directly over potential new customer corporate HQs while their Special Forces slip into US airports using gliders. It is going to be a full court press. I would warn Boeing to be on the look out for solo B-29s too. It is just that serious.
Too much hysteria surrounding this. It should have been a minor inconvenience to fix this and motor on. But Boeing MCAS set a trap for the unwary. Two major screw ups.....input from only one AOA and they made MCAS way too powerful. Let's stress this, the crew only PARTIALLY acted correctly and it was the 200 hour copilot who correctly called "stab trim cutout". Had they left that system off they would have survived, and it would have helped if 28 year old Captn had pulled the power back. Not all Boeings fault, several crews caught it....but then Boeing stuck their head in the sand and here we are.
Wingrat 1
Reading the news and hearing the news about the Boeing Max737 is really an eye opener. As the information gets deeper and deeper into the details I’ve got to wonder if this is a “can of worms” with wings. The investigation is intense
And the final outcome is way off.
So many innocent lives lost!! In this day and age!!!
Just terrible! Come on all in aviation. This is 2019!!
Investigate everything before this plane flies again!
Our families and friends fly and depend on your professionalism to keep us safe!
Scott Campbell 0
structural on a 60's based design ? Boeing would already be close to the NEW (none 37) single aisle winner with a base for a 57' replacement, whoever led at the time was wrong.
As frequent sand bagger in the back, the A 319 - 20 ( UN-tapered fuselage) beats the 37 every time just for PX space up front and at all window seats. But, the max 8.9 and 10 will be flying for decades. I will however avoid all 10's just because of the load time involved !
chop12345 0
Please introduce me to a co-pilot with 200 total flying hours, (unsure how many of those were in a 37), who could follow emergency procedures correctly. Listen to the VCR and you hear co-pilot Mohammed praying! Non-pilots don't understand why I won't fly on some foreign airlines. Hello!
chop12345 5
Before someone chastises me I meant CVR, I'm old and sometimes my younger days swirl in my head. At least I didn't state 8 track or 78!
Shenghao Han -8
Can we censor all news about the MAX news until the reports came out? They are already grounded....
Do wake me up if Boeing test pilots crashed one while testing fixes or when moving the undeliverable planes to storage...
btweston 8
Censorship is frowned upon in the United States.

There is a lot of information available regarding these crashes. Burying your head in the sand and lamenting people reaching reasonable conclusions will only make you look like a high school kid who just discovered nihilism.

Deep, man.
Shenghao Han -2
I don't know about you, there is a reason why NTSB agents shut off their radio as soon as they know some plane crashed.
There are just too many speculations, and I prefer factual news/articls been squawked on FlightAware.

So tired of seeing 737 MAX MCAS blah blah blah... By now the world knows MCAS have a problem, and this crash showed Boeing's emergency troubleshooting isn't effective...that is why all MAX were grounded, what more would this article achieve?

Boeing should take responsibility, no doubt with that, but what more you want from them by releasing more speculative article? Forcing them announce retiring 737 MAX family? Or closing its commercial aviation division?

In my eyes these cookie cut "MCAS lead to crash" articles does nothing but hurt Boeing's stock price and reputation. I am saying there is no meaningful positive contribution to the safety of commercial aviation, an article should be squawked should be news worthy, helpful to the pilots,engineers, airline executives subscribed to the daily squawks, not just "click-bait title" article that anti-Boeing or Anti-Airbus.
Censorship is frowned upon in the United States ? Maybe to the general public the idea of censorship is SUPPOSED to be wrong and we are not to be repressed of telling the truth....BUT REALLY? EVERY NEWS ARTICLE AND STORY THAT YOU HERE IS CENSORED IN ONE WAY OR AOTHER. WE ARE TOLD WHAT WE ARE TOLD TO BE TOLD. The brave few reporters or true journalists that refuse to play the game and try to get the real story to the public either is made to look like a fool over some made up scandal making all his or her work unreliable, or, found to be "suicidal" and dead in his hotel, or the victim of some corporate paid or politically bribed editor, having the entire story reworded and semantically making yes to mean no. There is no more freedom of speech in our developing "Federal Republic of the Communist States of America" , and we'll never know the truth from the higher ups of what really happened. All we do know is that all these people (aka guinea pigs or pawns, just like you and me and everyone not on the "privelaged level) were victims of a herrendous accident that tore families and loved ones away from each other and no one even focus on that anymore. It's who's going to blame who that's most important because somebodys going to not get his big corporate bonus or actually got caught bribing the wrong office in Washington to get what they want faster or come out ahead. Put your son, daughter, mother, father, sister, brother, in one of these passengers shoes and as a family member imagine how horrifying going day by day hearing the petty bullticky from these RE WRITTEN AND CENSORED stories Day after day when all you want to know is why and how to prevent it from ever happening to someone again and that your loved one will never be with you again,and all that's issued is a controlled and edited to perfection statement by the CEO read by some cold press rep on how deepest condolences go out to the family. I'm sorry but you may be right, censorship is frowned upon but that's all that we as the general public get to hear. Empathy is a glorious old school gift that has disappeared in the money hungry cold robot world.
Are you certain you are not mixed up between Putin's Russia where journalists have a strange habit of falling out of windows and the USA?
Roy Corrales 3
It's not recommended continue hiding the dirt under the carpet.
Shenghao Han -5
I meant to say "Can we censor all news about the MAX crashes..."
Cansojr 4
Censorship in the West including, Canada, United States, Europe and the Scandinavian countries. Australia and New Zealand would deeply frown on any attempt to implement a totalitarian news service like Russia Today, Pravda, and the list goes on. Why would you censor anything in open societies? Please take your censorship ideas and trash them.
Cansojr 3
I meant all censorship.
Cansojr 2
On April 3rd Boeing announced that it was accepting responsibility for both horrific aircraft crashes that claimed over 300 innocents. This announcement is like stating that there was a fire only they neglected to tell you over 300 people lost their lives to an incompetent instrument and sloppy oversite and programming by Boeing.


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