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Ethiopian Airlines 737 Max crashes killing 157


Nueces River Rat

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Hey I got a crazy idea, how about the pilots actually fly the plane, instead of the plane flying the plane.   WTF do you need an autopilot for, outside of taking a piss or a medical emergency?  Experience is key, Bobby nailed it.  The more automated the plane becomes, the less prepared a pilot becomes when they actually have to problem solve without panicking.  I think for me personally, that's why I believe the military pilots are more prepared....because they've seen some shit.

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3 minutes ago, mulletpelini said:

Hey I got a crazy idea, how about the pilots actually fly the plane, instead of the plane flying the plane.   WTF do you need an autopilot for, outside of taking a piss or a medical emergency?  Experience is key, Bobby nailed it.  The more automated the plane becomes, the less prepared a pilot becomes when they actually have to problem solve without panicking.  I think for me personally, that's why I believe the military pilots are more prepared....because they've seen some shit.

This right the fuck here.  No matter how much practice time you get, nothing ever replaces actual game time experience.

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The safety analysis:

Understated the power of the new flight control system, which was designed to swivel the horizontal tail to push the nose of the plane down to avert a stall. When the planes later entered service, MCAS was capable of moving the tail more than four times farther than was stated in the initial safety analysis document.

Failed to account for how the system could reset itself each time a pilot responded, thereby missing the potential impact of the system repeatedly pushing the airplane’s nose downward.

Assessed a failure of the system as one level below “catastrophic.” But even that “hazardous” danger level should have precluded activation of the system based on input from a single sensor — and yet that’s how it was designed.

 

Boeing engineers authorized to work on behalf of the FAA developed the System Safety Analysis for MCAS, a document which in turn was shared with foreign air-safety regulators in Europe, Canada and elsewhere in the world.

The document, “developed to ensure the safe operation of the 737 MAX,” concluded that the system complied with all applicable FAA regulations.

Yet black box data retrieved after the Lion Air crash indicates that a single faulty sensor — a vane on the outside of the fuselage that measures the plane’s “angle of attack,” the angle between the airflow and the wing — triggered MCAS multiple times during the deadly flight, initiating a tug of war as the system repeatedly pushed the nose of the plane down and the pilots wrestled with the controls to pull it back up, before the final crash.

But several FAA technical experts said in interviews that as certification proceeded, managers prodded them to speed the process. Development of the MAX was lagging nine months behind the rival Airbus A320neo. Time was of the essence for Boeing.

A former FAA safety engineer who was directly involved in certifying the MAX said that halfway through the certification process, “we were asked by management to re-evaluate what would be delegated. Management thought we had retained too much at the FAA.”

“There was constant pressure to re-evaluate our initial decisions,” the former engineer said. “And even after we had reassessed it … there was continued discussion by management about delegating even more items down to the Boeing Company.”

Even the work that was retained, such as reviewing technical documents provided by Boeing, was sometimes curtailed.

“There wasn’t a complete and proper review of the documents,” the former engineer added. “Review was rushed to reach certain certification dates.”


When time was too short for FAA technical staff to complete a review, sometimes managers either signed off on the documents themselves or delegated their review back to Boeing.

“The FAA managers, not the agency technical experts, have final authority on delegation,” the engineer said.

moar

Quote

Inaccurate limit
In this atmosphere, the System Safety Analysis on MCAS, just one piece of the mountain of documents needed for certification, was delegated to Boeing.

The original Boeing document provided to the FAA included a description specifying a limit to how much the system could move the horizontal tail — a limit of 0.6 degrees, out of a physical maximum of just less than 5 degrees of nose-down movement.

That limit was later increased after flight tests showed that a more powerful movement of the tail was required to avert a high-speed stall, when the plane is in danger of losing lift and spiraling down.

The behavior of a plane in a high angle-of-attack stall is difficult to model in advance purely by analysis and so, as test pilots work through stall-recovery routines during flight tests on a new airplane, it’s not uncommon to tweak the control software to refine the jet’s performance.

After the Lion Air Flight 610 crash, Boeing for the first time provided to airlines details about MCAS. Boeing’s bulletin to the airlines stated that the limit of MCAS’s command was 2.5 degrees.

That number was new to FAA engineers who had seen 0.6 degrees in the safety assessment.

“The FAA believed the airplane was designed to the 0.6 limit, and that’s what the foreign regulatory authorities thought, too,” said an FAA engineer. “It makes a difference in your assessment of the hazard involved.”

The higher limit meant that each time MCAS was triggered, it caused a much greater movement of the tail than was specified in that original safety analysis document.

The former FAA safety engineer who worked on the MAX certification, and a former Boeing flight controls engineer who worked on the MAX as an authorized representative of the FAA, both said that such safety analyses are required to be updated to reflect the most accurate aircraft information following flight tests.

“The numbers should match whatever design was tested and fielded,” said the former FAA engineer.


But both said that sometimes agreements were made to update documents only at some later date.

“It’s possible the latest numbers wouldn’t be in there, as long as it was reviewed and they concluded the differences wouldn’t change the conclusions or the severity of the hazard assessment,” said the former Boeing flight controls engineer.

If the final safety analysis document was updated in parts, it certainly still contained the 0.6 limit in some places and the update was not widely communicated within the FAA technical evaluation team.

“None of the engineers were aware of a higher limit,” said a second current FAA engineer.

The discrepancy over this number is magnified by another element in the System Safety Analysis: The limit of the system’s authority to move the tail applies each time MCAS is triggered. And it can be triggered multiple times, as it was on the Lion Air flight.

One current FAA safety engineer said that every time the pilots on the Lion Air flight reset the switches on their control columns to pull the nose back up, MCAS would have kicked in again and “allowed new increments of 2.5 degrees.”


“So once they pushed a couple of times, they were at full stop,” meaning at the full extent of the tail swivel, he said.

Peter Lemme, a former Boeing flight controls engineer who is now an avionics and satellite-communications consultant, said that because MCAS reset each time it was used, “it effectively has unlimited authority.”

Swiveling the horizontal tail, which is technically called the stabilizer, to the end stop gives the airplane’s nose the maximum possible push downward.

“It had full authority to move the stabilizer the full amount,” Lemme said. “There was no need for that. Nobody should have agreed to giving it unlimited authority.”

On the Lion Air flight, when the MCAS pushed the jet’s nose down, the captain pulled it back up, using thumb switches on the control column. Still operating under the false angle-of-attack reading, MCAS kicked in each time to swivel the horizontal tail and push the nose down again.

The black box data released in the preliminary investigation report shows that after this cycle repeated 21 times, the plane’s captain ceded control to the first officer. As MCAS pushed the nose down two or three times more, the first officer responded with only two short flicks of the thumb switches.


At a limit of 2.5 degrees, two cycles of MCAS without correction would have been enough to reach the maximum nose-down effect.

In the final seconds, the black box data shows the captain resumed control and pulled back up with high force. But it was too late. The plane dived into the sea at more than 500 miles per hour.

 

Edited by retread
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"* Economic problem. Boeing sells an option package that includes an extra AoA vane, and an AoA disagree light, which lets pilots know that this problem was happening. Both 737MAXes that crashed were delivered without this option. No 737MAX with this option has ever crashed."

https://twitter.com/trevorsumner/status/1106934362531155974

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Trevor Sumner @trevorsumner

1of x: BEST analysis of what really is happening on the #Boeing737Max issue from my brother in law @davekammeyer, who’s a pilot, software engineer & deep thinker. Bottom line don’t blame software that’s the band aid for many other engineering and economic forces in effect.👇🎖🤔
Some people are calling the 737MAX tragedies a #software failure. Here's my response: It's not a software problem. It was an

* Economic problem that the 737 engines used too much fuel, so they decided to install more efficient engines with bigger fans and make the 737MAX.
This led to an 

* Airframe problem. They wanted to use the 737 airframe for economic reasons, but needed more ground clearance with bigger engines.The 737 design can't be practically modified to have taller main landing gear. The solution was to mount them higher & more forward.
This led to an

* Aerodynamic problem. The airframe with the engines mounted differently did not have adequately stable handling at high AoA to be certifiable. Boeing decided to create the MCAS system to electronically correct for the aircraft's handling deficiencies.
During the course of developing the MCAS, there was a

* Systems engineering problem. Boeing wanted the simplest possible fix that fit their existing systems architecture, so that it required minimal engineering rework, and minimal new training for pilots and maintenance crews.
The easiest way to do this was to add some features to the existing Elevator Feel Shift system. Like the #EFS system, the #MCAS relies on non-redundant sensors to decide how much trim to add. Unlike the EFS system, MCAS can make huge nose down trim changes.
On both ill-fated flights, there was a:

* Sensor problem. The AoA vane on the 737MAX appears to not be very reliable and gave wildly wrong readings. On #LionAir, this was compounded by a

* Maintenance practices problem. The previous crew had experienced the same problem and didn't record the problem in the maintenance logbook. This was compounded by a:

* Pilot training problem. On LionAir, pilots were never even told about the MCAS, and by the time of the Ethiopian flight, there was an emergency AD issued, but no one had done sim training on this failure. This was compounded by an:

* Economic problem. Boeing sells an option package that includes an extra AoA vane, and an AoA disagree light, which lets pilots know that this problem was happening. Both 737MAXes that crashed were delivered without this option. No 737MAX with this option has ever crashed.
All of this was compounded by a:

* Pilot expertise problem. If the pilots had correctly and quickly identified the problem and run the stab trim runaway checklist, they would not have crashed.
Nowhere in here is there a software problem. The computers & software performed their jobs according to spec without error. The specification was just shitty. Now the quickest way for Boeing to solve this mess is to call up the software guys to come up with another band-aid.

I'm a software engineer, and we're sometimes called on to fix the deficiencies of mechanical or aero or electrical engineering, because the metal has already been cut or the molds have already been made or the chip has already been fabed, and so that problem can't be solved.

But the software can always be pushed to the update server or reflashed. When the software band-aid comes off in a 500mph wind, it's tempting to just blame the band-aid. 
 

 

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Im going to try to paraphrase whats here.

1.  The 737 MAX has a design flaw (engine placement) that can cause it to enter a stall unexpectedly.
2.  The design flaw was noted and "corrected" through a software system that would safely handle this scenario when it happens
3.  The above allowed the aircraft to be sold
4.  Profit!
5.  Detection of the stall scenario is dependent on the correct functioning of sensors on the aircraft
6.  This issue was noted and "corrected" through a warning indicator showing when the sensors are malfunctioning
7.  Boeing sold the aircraft with this warning indicator as part of an upgrade package.
8.  Profit!
9.  Some airlines bought these airplanes without the upgrade package
10. With lower costs involved in procurement, those airlines sold a lot of tickets for people to fly on the 737 Max
10.  Profit!
11.  BOOM!
12.  BOOM!
13.  Pilot error!  Pilot error!  Pilot error! Pilot error!  Pilot error!  Pilot error! Pilot error!  Pilot error!  Pilot error!

Thanks, guys. I have a new argument to present to my friends that believe "unfettered free market capitalism" has no downsides.  Though they'll probably characterize a few hundred dead passengers as part of a "market correction" that will eventually stabilize (flight pun intended).  It seems like this should never have progressed pass point 1 above and we have the topic for the opening episode of DirtyMoney season 2.

Edited by Goredho
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Btw, the answer is simple if people want to know why Boeing was so keen to re-fan the 737 or why airlines have been so tolerant of the Pratt teething problems. The Airbus NEO variants, for example, burn about 2 gallons per minute less at cruise than their conventionally powered counterparts. I imagine it’s about the the same for the 737. 2 gallons per minute of savings at $2-3 gallon multiplied by 4-6 flights a day turns into serious money. 

 

I was unaware, though I should have suspected, that an option to connect MCAS to two AOA canes and add a warning should there be a miscompare between the two. That adds a new layer to Boeing’s negligence in not making that standard and the airlines’ penny pinching to not purchase the system. 

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11 minutes ago, Bobby_Batronic said:

Btw, the answer is simple if people want to know why Boeing was so keen to re-fan the 737 or why airlines have been so tolerant of the Pratt teething problems. The Airbus NEO variants, for example, burn about 2 gallons per minute less at cruise than their conventionally powered counterparts. I imagine it’s about the the same for the 737. 2 gallons per minute of savings at $2-3 gallon multiplied by 4-6 flights a day turns into serious money. 

 

I was unaware, though I should have suspected, that an option to connect MCAS to two AOA canes and add a warning should there be a miscompare between the two. That adds a new layer to Boeing’s negligence in not making that standard and the airlines’ penny pinching to not purchase the system. 

Sounds like serious mfgr. negligence. That sucks, cutting corners/not being proactive always bites you in the ass.

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25 minutes ago, Bobby_Batronic said:

Btw, the answer is simple if people want to know why Boeing was so keen to re-fan the 737 or why airlines have been so tolerant of the Pratt teething problems. The Airbus NEO variants, for example, burn about 2 gallons per minute less at cruise than their conventionally powered counterparts. I imagine it’s about the the same for the 737. 2 gallons per minute of savings at $2-3 gallon multiplied by 4-6 flights a day turns into serious money. 

 

I was unaware, though I should have suspected, that an option to connect MCAS to two AOA canes and add a warning should there be a miscompare between the two. That adds a new layer to Boeing’s negligence in not making that standard and the airlines’ penny pinching to not purchase the system. 

I’m frankly surprised that a sensor in a system that is allowed to change a flight surface isn’t required to be 1x redundant at minimum. 

Just like I’d expect the wiring on the fly by wire systems to be at least 1x redundant so the plane does what the pilot asks. 

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9 minutes ago, Pato del Muerto said:

I’m frankly surprised that a sensor in a system that is allowed to change a flight surface isn’t required to be 1x redundant at minimum. 

Just like I’d expect the wiring on the fly by wire systems to be at least 1x redundant so the plane does what the pilot asks. 

This is where that Seattle times article kicks in.  The FAA delegated a lot of oversight to Boeing which has its judgment clouded by profit motive.  Oversight should be completely decoupled from who stands to make/lose money based on the conclusions of that oversight.  Otherwise, it ceases to be oversight at all.  Just hand waving to meet the narrative desired for the next quarterly report.

"The FAA, citing lack of funding and resources, has over the years delegated increasing authority to Boeing to take on more of the work of certifying the safety of its own airplanes."

Edited by Goredho
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Boeing is going to fry.

"After the Lion Air Flight 610 crash, Boeing for the first time provided to airlines details about MCAS. Boeing’s bulletin to the airlines stated that the limit of MCAS’s command was 2.5 degrees.

That number was new to FAA engineers who had seen 0.6 degrees in the safety assessment.

“The FAA believed the airplane was designed to the 0.6 limit, and that’s what the foreign regulatory authorities thought, too,” said an FAA engineer. “It makes a difference in your assessment of the hazard involved.”

The higher limit meant that each time MCAS was triggered, it caused a much greater movement of the tail than was specified in that original safety analysis document."

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“The FAA delegated a lot of oversight to Boeing”

What do they say...sometimes truth is stranger than fiction. Who the fuck made the executive decision to delegate the regulatory function over a for-profit company...to the company that you are supposed to regulate? Why don’t we go ahead and close the FAA and just be honest and tell the public that there is NO government regulation over the airplane manufacturing companies, because...money.

America’s “watchdog” institutions are in the shitter. SEC, FCC, FAA, and who knows how many others. But it’s cool, because money.

And nobody will go to prison. It was all just a misunderstanding, just like with the sub-prime robosigning farce.

Edited by XYZ
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Thanks, guys. I have a new argument to present to my friends that believe "unfettered free market capitalism" has no downsides.  Though they'll probably characterize a few hundred dead passengers as part of a "market correction" that will eventually stabilize (flight pun intended).  It seems like this should never have progressed pass point 1 above and we have the topic for the opening episode of DirtyMoney season 2.

Oh go fuck yourself you sack of shit.  This IS regulation, and it failed.  The idea that free market capitalism doesn't care about quality control is so fucking stupid it could only come from you.  We're the most regulated nation of earth.  You can't even cut hair without a fucking permit.  And yet...government supervision continues to fail.  Weird.

Go fuck your mother.

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3 minutes ago, PilotsError said:

 

 

Oh go fuck yourself you sack of shit.  This IS regulation, and it failed.  The idea that free market capitalism doesn't care about quality control is so fucking stupid it could only come from you.  We're the most regulated nation of earth.  You can't even cut hair without a fucking permit.  And yet...government supervision continues to fail.  Weird.

Go fuck your mother.

Well aside from the oedipus rex reference, I agree we're the most regulated nation on Earth (except when it comes to food). The problem is that regulation isn't always above board and thorough. 

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6 minutes ago, Pato del Muerto said:

Could also be a big reason the faa refused to ground the planes. They are culpable by deferring their job to Boeing. 

How would that help ?  If there were another crash that would only increase their culpability as it would then come out pretty plainly for everyone to see.

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7 minutes ago, Onboard 2.0 said:

How would that help ?  If there were another crash that would only increase their culpability as it would then come out pretty plainly for everyone to see.

Now that you’ve succinctly explained to me  how cover ups are bad, I’m left flabbergasted that anyone tries them. 

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2 hours ago, Pato del Muerto said:

I’ll need Bobby or someone to put those two conflicting numbers into perspective. 

Can pilot input  overcome a 0.6 degree command but not a 2.5 degree command?

what is the full range of motion of the elevators on this plane?

I have no idea what the full range of motion is on a 737 or the plane I fly. It’s enough to control the plane, and that’s what I need to know. I’m sure I could dig in a manual and find the answer, but it’s not important. 

The answer, however, is that the crew can overcome that kind of nose down. I know this because one crew in Lion Air did overcome it. The article suggests that they didn’t write the plane up to maintenance which I find very hard to believe. 

2.5 degrees over 10 seconds isn’t a huge amount. It’s not inconsequential,  it it’s not immediate loss of control. To put it in perspective we target about 3 degrees per second of pitch up at rotation on takeoff, and therefore take about 5 seconds to reach an initial pitch setting of 15 degrees. 

Boeing shouldn’t have offered a single sensor as an input for something like this, the airlines shouldn’t have bought it that way even though I’m sure both didn’t think AOA indicator failure was a very common occurrence and the pilots should have hit the stab cutout switches. 

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2 hours ago, Goredho said:

This is where that Seattle times article kicks in.  The FAA delegated a lot of oversight to Boeing which has its judgment clouded by profit motive.  Oversight should be completely decoupled from who stands to make/lose money based on the conclusions of that oversight.  Otherwise, it ceases to be oversight at all.  Just hand waving to meet the narrative desired for the next quarterly report.

"The FAA, citing lack of funding and resources, has over the years delegated increasing authority to Boeing to take on more of the work of certifying the safety of its own airplanes."

Well, I would suggest that the very few non-Western countries producing airliners of their own would have anything to brag about in this regard. The Soviets/Russians were killing people in airplanes at about the same pace as they were killing political dissidents.  

Dont cloak this thing up. 

Edited by Bobby_Batronic
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17 minutes ago, Bobby_Batronic said:

Well, I would suggest that the very few non-Western countries producing airliners of their own would have anything to brag about in this regard. The Soviets/Russians were killing people in airplanes at about the same pace as they were killing political dissidents.  

Dont cloak this thing up. 

Your life expectancy was in play few years back if you took at trip on one of those Russian/Soviet POS planes.   Compared to a Boeing or Airbus plane for sure.

I would rather walk across  Siberia than take a chance.

 

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14 minutes ago, GringoSalado said:

The whole idea of relocating the engines like that seems a bit janky for a modern passenger airplane.

It’s not. Airplanes are modified in unusual ways as their airframes are changed. The 747-8 has a whole new wing, motors placement and whatnot. The 747 SP has a huge tail because the rudder arm was shorterned so much. Go take s look at all the aerodynamic corrections on 1900D which is just a big King Air. Have you ever noticed that an MD-80 has wing root extensions with DC-9 wings bolted on, or seen the control surfaces added to the pylons of an MD-90 series to help get the nose down in a stall. The 727 and 737 had tail wheels added to prevent tail strikes as they were lengthened.  

Movin the motors a bit isn’t crazy, and is a lot more practical than designing a completely new airframe. 

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22 minutes ago, Bobby_Batronic said:

 

Movin the motors a bit isn’t crazy, and is a lot more practical than designing a completely new airframe. 

To be more precise they moved the engine in a way that altered how it flew enough to spawn that automated kludge to correct it which is now implicated in 2 catastrophic crashes. 

 

Is the max different from your other examples in its use of tech/automation/sensors (here I refer of course to the MCAS used as the "aerodynamic fix" that accommodated the engine change), or simply that they fucked it up (from the documentation to communication/ training, design, etc.)?

 

Should they have just said "the max requires x hours of sim training due to higher propensity to stall resulting from the new engines and their placement " instead of designing the mcas?

Edit

 

Forgot to add that I really appreciate your contributions on this topic

Edited by GringoSalado
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From the Seattle Times article, this in inexcusable by Boeing and the FAA  

The limit of MCAS’s command was 2.5 degrees.

That number was new to FAA engineers who had seen 0.6 degrees in the safety assessment.

“The FAA believed the airplane was designed to the 0.6 limit, and that’s what the foreign regulatory authorities thought, too,” said an FAA engineer. “It makes a difference in your assessment of the hazard involved.”

The higher limit meant that each time MCAS was triggered, it caused a much greater movement of the tail than was specified in that original safety analysis document.

The discrepancy over this number is magnified by another element in the System Safety Analysis: The limit of the system’s authority to move the tail applies each time MCAS is triggered. And it can be triggered multiple times, as it was on the Lion Air flight.

One current FAA safety engineer said that every time the pilots on the Lion Air flight reset the switches on their control columns to pull the nose back up, MCAS would have kicked in again and “allowed new increments of 2.5 degrees.”

“So once they pushed a couple of times, they were at full stop,” meaning at the full extent of the tail swivel, he said.

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Thanks, guys. I have a new argument to present to my friends that believe "unfettered free market capitalism" has no downsides.  Though they'll probably characterize a few hundred dead passengers as part of a "market correction" that will eventually stabilize (flight pun intended).  It seems like this should never have progressed pass point 1 above and we have the topic for the opening episode of DirtyMoney season 2.

Oh go fuck yourself you sack of shit.  This IS regulation, and it failed.  The idea that free market capitalism doesn't care about quality control is so fucking stupid it could only come from you.  We're the most regulated nation of earth.  You can't even cut hair without a fucking permit.  And yet...government supervision continues to fail.  Weird.

Go fuck your mother.

 

 

This is a classic case of regulatory capture and abuse of monopoly power. Rage all you want in the Cloak Room.

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2 hours ago, GringoSalado said:

To be more precise they moved the engine in a way that altered how it flew enough to spawn that automated kludge to correct it which is now implicated in 2 catastrophic crashes. 

 

Is the max different from your other examples in its use of tech/automation/sensors (here I refer of course to the MCAS used as the "aerodynamic fix" that accommodated the engine change), or simply that they fucked it up (from the documentation to communication/ training, design, etc.)?

 

Should they have just said "the max requires x hours of sim training due to higher propensity to stall resulting from the new engines and their placement " instead of designing the mcas?

Edit

 

Forgot to add that I really appreciate your contributions on this topic

 

I would suggest the documentation of the system, and communication with buyers is where it went wrong. I don’t know the significance of .6 degrees of authority versus 1, 2 or 2.5 is and where designers and overseers say “whoa, that’s getting wild”. Simply explaining that a system was installed to create a nose down moment in case of a high AOA situation or indication that is roughly 1/10 of that used on rotation, explaining the ways to counter it, and reinforcing the age old solution of using the stab cutout switches would be enough in my mind. 

The failures here can’t be pushed off on solely Boeing imoho. The FAA, buyers and pilots all bear fault in this case. 

2 hours ago, RPM said:

fify

Yes, cost is part of practical decision making, and you’ve traded off on added safety items and extra engineering in multiple parts of your life to meet that practicality many times. Boeing sold another 5000 737 production slots with this new variant. They and others dropped the ball with this design feature with regard to making everyone sufficiently aware of it, but ultimately the situation is very correctable with correct pilot action. Which means that the plane is as safe as any to fly now that this has been documented. 

And I’ll add another thing, you’ll know that those 5000 slots aren’t going away if you understand anything about Airbus’ ability to increase production or make future production slots available. Inshort, they couldn’t if they wanted to. So the Max is coming to an airport near you. And often. 

Edited by Bobby_Batronic
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1. It’s stupid that they allowed a system to make potentially catastrophic decisions based on the input of only one sensor

2. It’s stupid that they programmed it such that it keeps triggering the “nose down” repeatedly in between opposite inputs from the pilot. That’s like your car’s cruise control accelerating after you stepped on the brake. Multiple times.

3. It’s stupid that a system that will possibly point the plane down is not aware of the diatance to the ground. With GPS, there’s no excuse. The MCAS should have said “you’re stalling and I would normally point the nose down to save you, but you are too close to the ground to do that, so I won’t”

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5 minutes ago, XYZ said:

1. It’s stupid that they allowed a system to make potentially catastrophic decisions based on the input of only one sensor

2. It’s stupid that they programmed it such that it keeps triggering the “nose down” repeatedly in between opposite inputs from the pilot. That’s like your car’s cruise control accelerating after you stepped on the brake. Multiple times.

3. It’s stupid that a system that will possibly point the plane down is not aware of the diatance to the ground. With GPS, there’s no excuse. The MCAS should have said “you’re stalling and I would normally point the nose down to save you, but you are too close to the ground to do that, so I won’t”

I can name a plane who’s braking system takes two seconds to think about how much braking it thinks you need, and then applies that much braking once it decides on that amount. If you release the brakes and then reapply them it takes 2 seconds to reconsider the situation and reapply how much braking it thinks that you need. 

Needless to say, that type has spent a lot of time in the weeds next to runways, but it was allowed to remain in production until the braking system logic was recently corrected. 

The point is that it’s not a Boeing alone issue, or strictly an FAA issue for that matter. As some hinky stuff gets through. 

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^ I posted a video a page or two back with a pilot explaining all of the ways that the 737 tries to alert you as to potential stall conditions (besides the MCAS).

I'm sure it's been covered, but why did Boeing think that the MCAS was necessary? Did they think the MAX design was so different that stall conditions might sneak up on the pilots who were used to other 737s?

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3 minutes ago, retread said:

^ I posted a video a page or two back with a pilot explaining all of the ways that the 737 tries to alert you as to potential stall conditions (besides the MCAS).

I'm sure it's been covered, but why did Boeing think that the MCAS was necessary? Did they think the MAX design was so different that stall conditions might sneak up on the pilots who were used to other 737s?

Likely because there have been several major crashes in the last 10-15 years due to stalls (Colgan air, Air France, west Caribbean air) despite the fact that stall avoidance is a basic fundamental of pilot training. Trouble is, the fix seems linked to two major crashes in 6 months. I think shitty pilots are going to crash planes regardless. 

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51 minutes ago, XYZ said:

1. It’s stupid that they allowed a system to make potentially catastrophic decisions based on the input of only one sensor

2. It’s stupid that they programmed it such that it keeps triggering the “nose down” repeatedly in between opposite inputs from the pilot. That’s like your car’s cruise control accelerating after you stepped on the brake. Multiple times.

3. It’s stupid that a system that will possibly point the plane down is not aware of the diatance to the ground. With GPS, there’s no excuse. The MCAS should have said “you’re stalling and I would normally point the nose down to save you, but you are too close to the ground to do that, so I won’t”

If you’re going to hit the ground, you want to have horizontal velocity. It’s your best chance to survive so yea, even if the ground is close you fly toward it to pick up horizontal velocity. People survive crash landings like that. No one survives bellyflops that result from stalls.

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48 minutes ago, retread said:

I'm sure it's been covered, but why did Boeing think that the MCAS was necessary? Did they think the MAX design was so different that stall conditions might sneak up on the pilots who were used to other 737s?

As I understand it, they moved the engines forward with respect to the wing, so under power it tended to increase the angle of attack and therefore increase the likelihood of a stall.

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39 minutes ago, retread said:

^ I posted a video a page or two back with a pilot explaining all of the ways that the 737 tries to alert you as to potential stall conditions (besides the MCAS).

I'm sure it's been covered, but why did Boeing think that the MCAS was necessary? Did they think the MAX design was so different that stall conditions might sneak up on the pilots who were used to other 737s?

It’s not a “sneak up on you” stall condition thing. It’s the location of the new motors create additional pitch forces thing. The Leap motors make about 10% more thrust than an CFM56 for a 738, they’re located father forward meaning that their thrust is located farther away from the plane’s center of gravity giving them a longer arm to apply force and that high AOA air impacting the underside of the nacelles adds a further nose up moment because of that same location issue. 

 

As explained earlier, the Airbus will pitch down too if it senses a high AOA situation and impending stall. It’s not something unique to the Max. 

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I didn't ask that as well as I should have. Based on that pilot's video describing the safeguards (e.g. instrumentation, audio warnings, etc.), I thought maybe the plane would go nose up faster than other 737s. You could potentially go from a safe position to one approaching stall (nose too high) quicker.

Sounds like that's possible with the increased moment/force and the nacelle profile.

 

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9 hours ago, Bobby_Batronic said:

I was unaware, though I should have suspected, that an option to connect MCAS to two AOA canes and add a warning should there be a miscompare between the two. That adds a new layer to Boeing’s negligence in not making that standard and the airlines’ penny pinching to not purchase the system. 

Deep Capture or not, it's now nut cutting time for the major players.  I suspect the rest of the world will keep their bitching to a minimum to see how the big players deal with this.  I believe the first rodeo will be the AOA Compare "feature".  Is it installed on some or all of the AA/UA/WN metal?  Will the big 3 "work" with Boeing to tightly control this messaging?

If aa/ua/wn bought the "feature", good for them, bad for Boeing.

If aa/ua/wn didn't buy the "feature", bad for them, good for Boeing.

The FAA is fucked either way.   So option 3 is maybe aa/ua/wn/boeing circle the wagons and the faa is exscapegoated.

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3 minutes ago, Hagbard Celine said:

Deep Capture or not, it's now nut cutting time for the major players.  I suspect the rest of the world will keep their bitching to a minimum to see how the big players deal with this.  I believe the first rodeo will be the AOA Compare "feature".  Is it installed on some or all of the AA/UA/WN metal?  Will the big 3 "work" with Boeing to tightly control this messaging?

If aa/ua/wn bought the "feature", good for them, bad for Boeing.

If aa/ua/wn didn't buy the "feature", bad for them, good for Boeing.

The FAA is fucked either way.   So option 3 is maybe aa/ua/wn/boeing circle the wagons and the faa is exscapegoated.

Wait.. so what time does a train leave Chicago ?

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31 minutes ago, Bobby_Batronic said:

I think it’s possible and that nose down pitch forces required to avoid a stall are greater without MCAS. Boeing is trying to make the Max fly as much like an NG as possible. 

Dude, i really appreciate your perspective on this thread, even if, as a layman, it seems like a massive design failure. Your comparing it to other design failures does not move the meter for me, but i get it. My car has design failures that i deal with every day. But this seems different. 

The example above of your cruise control accelerating every time you hit the brake resonates. "All you gotta do is toggle off the cruise control..." Except sometimes people panic and that is an unnecessary design fault. 

Can you comment on the correction amplifying every time the pilot tried to correct?

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The difference is, the Lion Air and Ethiopian crashes, the pilots couldn't and/or didn't know how to turn off their cruise control.  And in an airplane, you can't turn the car off and pull over.  In an airplane you have to know that 1) you have a cruise control, 2) you need to know how to turn it off, 3) you have to know how to drive the car, rather than expect it to drive itself.

That said, 24 hours ago I didn't know Boeing had not "told" "everyone" about the MCAS and it appears they "did not".

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