Thank you sir.! 100%.

Well said

This is a technical report and discussion so please kindly understand the focus is on the cause not all the other sensitive matters. We all respect loss nothing can change that fact.

A Jonesy Thank you for your explanation and your sensitivity toward the pilots and families who are grieving their loss.

Awesome comment, thank you very much sir.

Large TV channels definitely but news media is more than the vacuous talking heads on the telly with nothing but commentary and soundbites! There's, you know, actual press with journalists that dig deep into these things. In this MAX 8 case, read the reporting of Seattle Times for instance.

well, these are journalists who have studied journalism and have no knowledge of aviation or engineering whatsoever. the best they can do (which often they don't) is interview someone with expertise and give them 30 sec of airtime with several interruptions whenever it get's interesting. he on the other hand is a pilot and instructor. youtube = cut out the middle man

@Thomas Headley- "Fake" president?? Despite your preferred candidate not winning, according to the presidential election system prescribed in the US constitution Donald Trump won (the Republican primary and) the electoral college. Unless he was discovered to be constitutionally disqualified, he is the president of the United States. He is a documented natural born US citizen by being born to US citizen parents and by being born subject to the jurisdiction of the US. He was elected by the electoral college. He was over 35 on his date of being sworn in to office. He swore to support the US constitution. What further requirements do you think there are?

@Tickey Horseman We don't "trust" the MSM, we are supposed to analyze data from MULTIPLE sources, attempting to determine which of those sources is accurate for that data point and go from there. Saying 'fake news', but not requiring the raw data -means you "trust" the guy claiming fake news. But if they won't provide the raw data, then trusting that person is a sucker play. It's very similar to the idea of redundancy.

We're not supposed to notice, let alone say anything if we do notice. But the fact is, Israel lobby billionaires control the "mainstream" media -- sometimes their supporters even brag about it.

Chuck Cummins Hi Chuck! As a Max pilot, do you know if western airline companies purchased the full safety MCAS system of the 737 Max, considering - if I have well understood - Lion Air and Ethiopian Airline had the standard configuration?

Hi Franco I don't have the answer to that. It's a good question.

@@hernanni5 Only Southwest I believe. American might have purchased it as well but I'm not sure.

Chuck Cummins it is mentioned in the NY Times article of 21st of March. American Airlines bought both safety provisions. Southwest bought the disagree light and did an after install of the angle of attack option. United Airlines has neither the angle of attack indicator nor the disagree light. The main issue here seems to be that other countries relied on the FAA approval. This will not happen again anytime soon, so I ‘look forward’ to President Trump defending the interests of Boeing against European countries who don’t trust the FAA anymore and will want to do their own certification tests. He’ll probably order retaliatory measures for Airbus planes and the Chinese will love it. What a world we live in.

It was very good to hear this explanation. I recently began working at Boeing was supposed to be on the 777x but got moved to the 737max to help out. The attitude toward this stuff is something to behold, people here really do care about the vehicle we are producing and the people flying on it. The aircraft are exceptionally well put together from what I can tell, and I am a junior in aerospace engineering working as a assembly mechanic currently so I get to know the vehicle pretty intimately but hearing the pilot side is great. I personally would not hesitate to fly on any of Boeing's planes, granted nothing will ever be 100% risk free. I also trust that the pilots in the US are some of if not the best and most knowledgeable about aerospace in the world and can only make things that much more safe. I am not even trying to throw a sales pitch for Boeing, I just really appreciate how careful they are when building these birds...

Great point thanks Chuimon!

@@blancolirio welcome sir, thanks and keep 'em coming!

YES!! And without the "Boeing stocks" graph in the top left corner showing us $$ money in the last week. Jesus. Makes my blood boil.

Agree.

The MCAS system was not incorporated simply to prevent a stall. It was developed to compensate for the larger engines, which have to be mounted further forward of the wing, so that the pilots wouldn't need expensive retraining to learn how to handle the extra pitch-up on throttle up. Instead, the MCAS would take care of that. The alternative would have been to increase the size of the horizontal stabilizer. That, like the retraining, would have added more cost.

Excellent explanation though. Really excellent!

420 knots, in the weeds, hugging the stick... he made a choice.

This lesson was learned 50 years ago by NASA..... If you're going to have a fly by wire system and a computer will have any ability to override pilot inputs then triple redundancy is appropriate... The aerospace industry standard is 3 independent sensors feeding into the flight computer or computers and polling those sensors... if one os giving jibberish and 2 match the one is discounted... if 2 fail the system is disabled and manual reversion or pilot control occurs... Why Boeing did not build any redundancy into MCAS and then gave it so much control authority boggles my mind... The cost would be one extra AOA sensor and some software additions... This error probably has fatally hurt the MAX aircraft its basically the DC10 all over again the PR will take years to shake... All over a software solution looking for a problem because some techy behind a desk thought a pilot couldn't recover from a stall????

@Asa MeredithI'm beginning to suspect that the architecture of the left right ADC (Air Data Computers) may have prevented the left and right sensor from being compared since the philosophy of the system is to move instruments from one side of the cockpit to the other to the wherever the pilot flying. Remember the B737 is built around a 50 year old architecture and is not a triple redundant fault tolerant architecture we see on Fly By Wire Systems on B787/B777/Airbus. It seems to have just two of everything. The Sensor Disagree Alert Seems to have been part of the optional Angle of Attack display and would have been computed in the separate computer in the display that was able to access data from both sensors. So I'm thinking there was some kind of system constraint that stopped the MCAS guy from accessing both sensors.

@Todd Cory wow!

That's alottawatta

MAX8 not, 737-800. Two different airplanes.

@@danjacobson9861: I stand corrected.

@@danjacobson9861 (just for lay people like myself who may be crapping themselves because they thought they were on the same plane). Thanks

A lot better than the new gens. Do you remember how roll sensitive it was during a Flaps 40 landing...they computer enhance the spoiler and it feels like a Flaps 30. Also...a left and right cup holder.

Thanks Nahlah! Stay tuned...

Good point on the difficulty with manual trim. In Juan's previous video on this topic he mentioned and linked to a video demonstration by Mentour Pilot on the runaway trim procedure. During that demonstration, both the pilot and first officer had to work the manual trim wheels together in order to adjust the trim. The first officer alone was unable to effectively work the manual trim wheel.

Seems like they decided it was too hard to manually trim the aircraft, so they reactivated the electric trim motor to use that.... and MCAS ran it back to nose-down trim again. Apparently they needed to cut engine power and reduce speed, so that the aerodynamic forces wouldn't be so severe on the stabilizer, and then use manual trim. Unfortunately it also sounds like they were too close to the ground and didn't have the time or altitude to do that. :-(

RayDT indeed, all the more with the already very high altitude of the airport itself !

Great quotes. Why not listen to pilots feedback during the design phase??? They'll tell you how they like MCAS Version 0.1

Did they ever tell you what to do if you're flying in the dark of night, engines out and going down, and you don't like what little of the cliffs and boulders you can see with the landing lights?? Turn the lights off.

@Ardent Fan Exactly. I expanded on this in reply to another commenter. It was never Boeing's intention to reveal the existence of MCAS. Unfortunately, events have forced their hands and confidence in the regulators as the last bastion of protection is now shaken.

Ahh, the days of reporting the actual event without possibilities, dodgy eyewitness accounts or advertising. Sooooo refreshing hey mate

Thanks Dustin!

Precisely! Unfortunately reducing airspeed was probably not on their checklist, due to stall warnings.

You've summed it up nicely. Further to that though I would say that when redundancy detects that the primary sensor inputs are unreliable the dependent system should switch ITSELF off. But Boeing failed in two further ways additional to allowing MCAS to take control of the plane based on a faulty input: 1) not providing a clear indication to the pilots that MCAS had kicked in and was forcing the nose down, and 2) not providing a way to disable MCAS while still preserving motorised trim control on the yoke. Both of which you covered in your post.

@D Madd11 If you read the preliminary accident report and 737 trim system information Juan supplied above, you can see that three generations of pilots, all since 1967, have been required to memorize the steps to overcome an elevator trim overrun failure (MCAS is just one of the possible causes) by moving the elevator trim cutout switches to the "cutout" position, control the plane with yoke to a safe flying altitude, attitude and speed, THEN to manually trim the aircraft with the manual trim wheels. And most importantly, the memory procedure contains a final instruction not to return the elevator trim cutout switches back to the on position. This pilot disengaged the MCAS and automatic trim systems. He then failed to regain control of the plane, allowing it to pass 500 knots, way over Vmo, failing to slow the plane down to unload the trims so they could be manually adjusted after he followed his first ground school instruction before he stepped into a Cessna 172: FIRST FLY THE PLANE. Once you have control in a safe attitude, altitude and airspeed, THEN AND ONLY THEN troubleshoot peripheral problems. This pilot twiddled with trim controls when he should have been flying the plane. Then he switched the elevator trim cutout switch back to on, against the memory procedure he was required to fly by. It is as if a terrorist seized control of the plane attempting to dive it into the ground. The crew overpowered the terrorist, regaining command but not control of the plane. Next they decided it would be better to put the terrorist back into control, whereupon he immediately did what he set out to do to begin with: crashed the plane. Substitute MCAS for terrorist in the last paragraph. Now, who crashed the plane? Of course the proximate cause was the terrorist performed a controlled flight into terrain. But the actual cause was the pilot put the terrorist back in control. This is pilot error. Now, can Boeing increase the safety of the plane? Of course. ALL planes can be made safer. But in their position, with all the haters in the world after their blood, CAN they fix it? They probably will do so even though in the present climate of misinformation the news media will interpret it as admission that the plane was dangerous. A lesser corporation wouldn't change a thing, rightly claiming the plane is safe and admission of fault by unnecessarily improving systems doesn't keep any future pilot from crashing the plane, should he be sufficiently determined, but would expose Boeing to significant liability exposure. Isn't that the result of many, many of these witch hunts? In the name of aircraft safety, they actually make flying much less safe.

@@ianhinson2829 There is no need for an additional indication of an MCAS trim input, a competent pilot would most likely not get the aircraft into that configuration and an incompetent one will either already know the runaway trim procedure or just crash. The point being made about the tension on the jackscrew still stands whether or not you're trying to use the switches on the yoke or the wheels; you have to unload by pitching down if you want to adjust the stabilizer trim at such excessive airspeed.

@@robroilen4441 Pitch down at ~1000-3000 ft AGL?????

@@MarioBoyRoblox360 Yes. Not exactly a by-the-books maneuver and in this particular situation probably not a fantastic idea, but true to design either way. As mentioned, the MCAS system can only operate when flaps are up and autopilot is off, so there was in fact a configuration that could have saved the aircraft.

_I like your informative and timely Avatar !!!_

Star Gazer How? If they couldn’t manually trim?

Fact They tried to use AP while stick shaker on They never disengaged auto throttle They had one ir perhaps mire window

Of chance Apparently captain never heard of indonesia crash

@Sasha R trim manual control is very very slow response, the altitude and time was too low, 500 knt or 300 knt is not much different while altitude reduces several times by the MCAS nosing down, and how slow we can save the plane? its very very hard time.

Thanks Randy!

Kreemerz ...Yes fuckwit.

@@blipco5- Don't be so hard on a 10 year old troll.

Thanks Juan most comprehensive explanation in this accident, how you explain Juam that that trottle wasent move in entire dive flight.why cut off trust to gain time.?

@@stefanstroh I think I know what you are asking--The engine thrust needed to be retarded to relieve pressure on the stabilizer, thereby giving the pilots an opportunity to pull the control yoke . they had plenty of speed already.

The news media are professional at misleading the public, they see it as their jobs.

ikr mainstream news is totally useless.

lol regular news isn't used to making facts their priority

I'd say panic was setting in by then

The pilot only got around 30 second..to response for accident

That's what I thought. They couldn't get the manual trim to work, because of the force, and thought, try the electric trim and hope it reset

Reducing engine power would definitely pitch the aircraft down. The 737-MAX is more sensitive to this than other 737s which is why (for the opposite situation, increasing engine power causing a pitch up) the MCAS system was added.

​@@rhamph1 Reset Stabiliser Breakers, 2 Immediately Trim Up using trim switches thereby disabling MCAS, 3 Pull the breakers before MCAS can move the Stabiliser again. Its with the benefit of hindsight but they did have a slim chance.

@WHITE DIAMOND You should stop shouting if you want people to read your comments.

@@BlueZirnitra if I had no answer for his very astute question I'd also go with being a grammar Nazi.

Dig deeper. There is a way to donate to offset Juan's production cost; to help him invest in better cameras and upgrade editing software. Also, help him with upkeep on his Luscombe!

birdwing98 unfortunately, it’s NOT on this video update,. Cheers from NJ

But you can't learn what isn't told to you! MCAS was invisible to the pilots. Even after the Lion Air crash when the system was brought to light there is a lot of confusion on exactly how it works and this accident is clearly showing how powerful and insidious this system is. Competent and well trained pilots would have been able to deal with this issue IF they were made aware and trained to counteract a malfunctioning MCAS. However, Boeing did not want this to happen as this would mean expensive Level C or D simulator for the airlines, defeating a key selling point for the Max. This really shaking my confidence in the 737 Max forever because MCAS is such an integral part of the aircraft. I think the final solution to restore confidence is for the FAA to modify the certification of the Max to require the ability to turn off the MCAS fully and require training to handle that. This is going to be costly which Boeing will be responsible for but in the long run l think is the best solution.

@@jaminthomas It would seem by this preliminary report that the pilots made the right choice by turning the MCAS system off but then lost control through over speeding the aircraft followed by multipel misguided attemps to recover without the benefit of situational awareness.

@@ecomindedchoice My reading was that the pilots did the right things but had a couple of missing elements. Altitude and time. That gives you time to try other things and towards the end it was pretty desperate. Bjorn Fehrm runs through a detailed analysis on Leeham News. Like Juan he was a fighter pilot.

@@iangill8984 The excess speed made the manual trim unusable. It was when they were unable to manually set the trim that they lost control of the airplane leading to the crash.

@@ecomindedchoice At this point we wonder why they kept such a high speed. Found themselves unable to trim manually, could it be speculated that they turned the stab trim cutoff switches back on in order to exploit the electrical trim for a moment, with the intention to turn it off as soon as the stabilizers were “lighter” to trim manually?

@@kradius2169 You are completely right to point that out. Based on the timeframe from conception to initial commercial flights I think it would be unfair to say the program was rushed. What was rushed was my comment. And in keeping with the well researched and careful nature of the original video I have removed the incorrect statements. I had a different point and worded my comment very poorly.

@@richardskingdom You get 1 million internet points for integrity and strength of character my friend.

@@danhillman4523 The pilots did nothing wrong, there was nothing structurally wrong with the aircraft, those people were killed by a software bug that made it through how many levels of verification?

Ray G There is no software bug! The MCAS does exactly what it was supposed to do by design. There is a major design fault in terms of systems safety ( robustness to component malfunction and man-machine interface ).

@@joso5554 You mean crash an aircraft? Because that's what it is capable of as proven by two accidents. There is not enough cross checking of the flight instruments by the automation systems to identify invalid signals, that's a software bug.

My guess... higher-ups decreed that AoA anomalies shall be considered a low risk event (which did happen, one way or another, and by the rules meant they were allowed to get away with reading only one of the two sensors). That's regulatory capture for you and, in this case specifically, enabled by self-oversight and not funding the FAA at a level necessary for the work! Now consider what else has been neglected. FDA, EPA, you name it.

That is not the only surprising story. On the military aircraft (kc) the MCAS system exists - it reads from two AOA sensors and the pilot can disengage it. What is so fucking is that how boeing engineers ( i rather call them interns), striped the safety and fitted with no redundancy on the max!!!!!

yisjobTube can you bring some more info on the MCAS system on mil transports? when / on which type was it first introduced ? was it actually named MCAS ? was it mentioned in aircraft documentation ?

I suspect that it’s got to do the the architecture of the two ADC “air data computers” and the 50 year old system philosophy of B737. There are only two ADC not three. It’s not a triplicated fault tolerant system and relies on the crew identifying the faulty computer and instrument and manually switching over to the good side of the cockpit. The architecture may not have supported the programmer easily accessing data from both sensors. The sensors are connected to only 1 ADC each although the ADC cross connect. It’s also incompatible with the philosophy. I’m a PLC Programmer not an avionics expert but there is more to this than a simple bug or oversight. The sensor disagree alert was part of the display system I think not the ADCs. The software upgrade Boeing have produced has made the system failsafe but it’s not fault tolerant. You need minimum of 3 sensor and CPU for that

@@WilliamJones-Halibut-vq1fs Oh man, that makes total sense to me but I'm no expert on any of this - but it would fit perfectly into why there may have been a drive to rank the risk from an AoA indicator anomaly as low as they did. I forget the exact terminology, I only read the Seattle Times article once, but with a sensor failure and its repercussions ranked artificially low enough the regulations allowed them to implement the system the way they did... and the rest is history. Gaming the system to get the answer they preferred instead of taking on a more fundamental overhaul and the work, time and expense that would thus be necessary. Passengers are just a commodity, not customers for the higherups.

Yes it seems the high speed was the really crucial factor in this accident, the report says there was no change in the throttle inputs all the way to the tragic end, and there was no system at fault there. Due to the high speed the FO could not manually trim the aircraft. First thing you are taught (as a pilot of whatever type) in handling an emergency is FLY the airplane. Then deal with the emergency.

@@Kosmonooit Maybe if they cut power and popped open the spoilers to slow their speed when the aircraft started to dive, maybe they could have had more time to recover the trim manually.

JohnnyBoythePilot That cuts a major force keeping the nose up coming from the engines.

There is no way to be sure, and most likely they didn't have time to think about it (what with the highly intense workload of dealing with an out-of-trim aircraft at this altitude). But perhaps the nose-up moment coming from the high thrust setting (the reason MCAS was implemented in the first place) was of benefit to the crew. Although at some point that balance was likely skewed and the high airspeed put too much force on the vertical stabilizer for them to trim it back. In all of this I do not understand how such a critical system was designed to take input from one sensor only.

If they had throttled down, then the nose would have pitched down even further. On another note, am I wrong or did I see somewhere that the MCAS actually controlls the throttle input of the airplane as well?

MCAS the system from hell. So I assume maintenance manual is also at fault.

The MCAS is badly designed as it lacks the redundancy of using two AOA sensors during a flight. Safety demands that but somehow what was obviously necessary was not implemented. Why?

@@osakarose5612 I've never worked in avionics but I work in software in the oil industry every sensor throws an alarm for faulty readings. So it will be in the alarm log, and also historic data. I've seen systems that use 6 encoders for redundancy and if one encoder disagrees is automatically taken out of system. Surely it has to be more advanced in planes? As an ex maintenance myself I would have tested both readings from. both AoA sensors.

WTF? This is the first I've heard of this.

Tower Runner Good points. The MCAS AOA alternates between flights, except when powered off during maintenance, after which it always resets to captain side.

The headlines now say so because of this preliminary report.

15:20 followed the procedure initially but when they couldn’t manually trim they turned it back on, that was the fatal mistake.

@@agentbb007 This makes me think. There are two switches, "main elect" and "auto pilot". Is that possible that the mistakes was to believe that they could turn on just the "main elect" and this would have prevented automated "pilots" to intervene? In this case it would have been a misunderstanding of the systems which can command the stabilizers - or just a desperate last hope. Also, this makes me think of another design flaw in this MCAS: the stab trim autopilot switch in cutout position should be sufficient to disable it. This would allow electric manual trimming, which is the only hope in certain circumstances. And of course, the runaway stabilizer check list would change so that you put in cutout also the "main elect" only if the runaway event continues despite having the autopilot in cutout.

Stephen, >the horizontal stabilizer trim jackscrew motor has no mechanical connection to the trim wheels on the control console. By turning a wheel with the hand the motor shaft or the jackscrew nut are not turned mechanically. "Manual" can mean only that the computer is not involved.< Part between > and < is wrong. I misinterpreted my source. It does look bad that by turning the MCAS off the system doesn't revert to input from the control panel wheel.

@@algrayson8965 What has been said is those manual trim wheels are mechanically linked by cable to the jack screw, no hydraulics or electrics involved. They couldn't manually trim the aircraft because it was going so fast. One could say the could have momentarily enabled the electric trim to trim up in stabs and before the MCAS did its thing but so easy to say from the sidelines right now.

*@Al Grayson* A minor point but the screw is the only part of that stabilizer trim system turns. The nut is linked, in some way, to the front of the stabilizer. You do say "motor shaft or the jackscrew nut" but I just wanted to add a bit of clarification. You do say, in your follow-up comment that the mechanical trim wheels in the cockpit are manual all the way, with cables.

@@algrayson8965 - Mentour has described how the trim wheels are mechanically connected to the jackcrew motor by an old-fashioned cable drum system. At the airspeeds recorded, the trim forces required would have been beyond the capabilities of the motors or the handwheels.

@@paulavery366 - Thanks. I will go back and find my erroneous comment and add your correction.

Thanks Brad. Just gutted me when I read that report.

@@kradius2169 Thet clearly did exactly that, or they wouldn't have known (as stated) that manul trim was ineffective.

Media misinformation, probably from Boeing, to deflect the real cause, Boeing and FAA. the pilots were true heroes. May they rest in peace.

Thanks Don.

So sad for her family. I'm so happy, though, that they will see her again

An Which Muslim Country would that be?? Lol, Stay in Your Basement An Stop Talking Things if you have No clue about.. that’s The Problem With Kids Today..Just Cause you have Internet Doesn’t Mean You Know What’s Going On Around the world.

Kreemerz Nothing hateful in Warsame’s comment about a particular religion. I have no clue why the original commenter would even think it relevant to this topic.

The aoa vane flap like a nation flag - plus and minus 14-deg or more and averaged to plus (pitch up). Either intermittent electronic problem or the vane had service ribbon attached and remain attached after maintenance until crash.

I think this is where Boeing is going to be held to account, having such a system only rely on one sensor. Did they (the dev team) think through every eventuality? Prophets of Autonomous Vehicles take note.

@@philoso377 while you can smooth the values electronically ( through low pass filters) or arithmetically ( via averaging) you would imagine simple oil or other viscous fluids would prevent a lot erroneous measurements due to that flapping

Martin Visser kats

YK Chan by u b17 by see see st bu k v k

I respect ur opinion sir, but are u trying to blame the pilots?

Good observations though it does seem to suggest the crew "failed" to deal correctly with the trouble presented therefore the burden of responsibility for the loss lies with them. I'd suggest... - the allotted 1-minute of elapsed time to troubleshoot and diagnose a fault that in it's early moments was not severe seems rather an unfair burden to place on pilots. Passenger's want a robust a/c where the crew may achieve a letter "D" grade on this type of test and not die. - commercial aircraft should be designed to be fundamentally stable in flight, and bad characteristics not allowed for the sake of fuel economy then masked via slipshod f/c programming. - " a single point " failure should not have been designed to create danger to the degree this system has. Two new a/c lost in a short period of time as a result of what appears to be originating from the same "single point" component failure smacks of a design fault(s). Passengers don't want to fly in a/c where the crew is expected to be lucky or at the pinnacle of their game otherwise dead.

pasphil c I think everyone agrees that the pilots made some mistakes. However they did not cause the accident, that was triggered by MCAS. Trying to attribute blame does not help anyone.

@@pasphilc7994 the job of the pilot in command is to be able to deal with any and all systems malfunctions. a failure of the AOA in some form or fashion is no different then say a failure of System A or B hydraulics or an engine failure or whatever... the automation is a little more tricky to deal with but yes the pilots made error after error in dealing with an static sitution if on stick shaker (which was known to be in error) the pilots had followed standard training procedures and 1) not connected the automation including disconnecting A/t 2) stablized the plane at some altitude in the take off configuration ie flaps 1 or 5, (ie the airspeed unreliable checklist) 3) possibly taken the stab trim cutout switches to off (but as long as teh flaps are down this was not needed) and 4 returned to Addis...they would be alive. its not rocket science...its airmanship

@@gordonrichardson2972 no they caused the accident. in accident investigation parlance the failure of the AOA in some manner was the trigger event. they then proceeded to handle the plane and its systems badly after that. all pilots and the PIC must be able to deal with systems malfunctions and not lose the plane

I read that boeing made MCAS a certain level below hazardous to avoid making it redundant and to avoid having the plane be another certificate level to avoid millions in re training and certification. I think a 10yo with a raspberry pi could have designed a better system surely boeing engineers could too, but I believe greed at the top got the better of them. Also they were pressured by airlines to deliver fast or else go with airbus.

According to previous reports the MCAS system only takes input from one AOA sensor. Since it doesn't 'see' the other sensor MCAS cannot detect if the AOA sensor data differs. There is an option on the 737 Max to have an on-screen indicator display a warning if the AOA sensors disagree but not all 737 Max buyers have taken the option.

@@davetaylor9057 An option by Boeing to buy this? Dam. Just the thought of selling this as a frill item sucks. It's all about profit maximizing by Boeing. Lives don't matter.

Not only that, the manual system failed too. The trim wheels turned out to be useless in an emergency situation, which they were supposed to be used in. MCAS system failed, AOA sensor failed, and backup manual wheel failed too. How did Boeing's planes got certified for so many years?

Philip W No aircraft is expected to prevent a single failure. Safety must ensure that no single failure (unless its probability is extremely remote, which no electric/electronic component has) can endanger the flight. This is a matter of design choices, such as redundant cross-checking architectures etc. An AOA sensor, like any component, must be allowed to fail without endangering the flight. The MCAS system did not fail, it did exactly what it was (poorly) designed to do. Here we have a single failure causing a fatal accident, and the blame is on the overall design (especially MCAS design), not on the AOA sensor which noone should expect to be perfect.

The location of the wheels make them awkward to crank particularly if there is any significant load.

Internet Privacy Advocate + I’ll partially agree with you on your statement. If you’re like 90% of the world, being a left handed person is usually an impediment. However in the case of the manual trim control wheels, being left handed as the co-pilot would help. The spring loaded handles are 180 degree opposed making manual operation like operating a two man saw. You’ve got to work together. There is no ideal location for the trim wheels that would allow for manual operation.

Not really. What is not readily apparent to the crews, is the fact that the manual handles of the trim wheels are offset 180 degrees from each other, (just like the pedals on a bicycle) strategically placed this way, so if necessary, both crew members can exert maximum cranking force on each respective handle to get the horizontal stabilizer moving in the desired direction, in this case, nose up. I have done the exercised described by Juan many times in the B737 simulator sessions as part of our training profiles at Varig Brazilian Airlines. Flying at 420 knots close to the ground, both pilots of Ethiopian flight 302 would have to exert considerable force on the trim wheels to get it move out of the binding situation described. The crew got distracted with the flight control problem and never reduced the thrust of the engines. This compounded the situation.

Given that the stabilizer was so far out of trim, I assume Pilot was applying significant pressure to the yoke whilst the Co-Pilot attempted (and failed) to manually adjust. Re-engaging the motors to adjust the trim must have been an act of desperation, and Dis-engaging them a 2nd time appears to have been overlooked before MCAS 'corrected' once again. From the descriptions given it is not clear whether the motor for the jack screw is directly attached to it and thus the wheels in cockpit are turned via the attaching wires/cables, or whether the motor is attached to the cockpit end. Seems to me (arm-chair mechanic) that ability to manually adjust should have possible in all situations, regardless of aeroloading. Is the nut a regular threaded part, or a 'ball screw'?

@@mungewell The B737 Max has one trim motor attached to the stabilizer trim jackscrew located in the tail cone of the aircraft. After the trim motor is disabled by the Stab Trim Cut Out switches in the OFF position, the crew can manually position the stabilizer trim via the cockpit trim wheels in the cockpit which are mechanically linked through cables to the stabilizer trim drum in the back. The crew of ET 302 was facing extreme aerodynamic loads in the horizontal stabilizer, as the aircraft was allowed to accelerate well beyond its maximum certificated airspeed of 340 knots. At one point the airspeed is recorded at 480 knots!! This might have given the notion to the crew that the manual trim was also not working, prompting them, we suppose in an act of desperation, to re-engage the trim motor which enabled MCAS again, dooming the flight. The Ethiopian preliminary report is not complete. The FDR and CVR readouts must be superimposed in time, so investigators get a full picture of what was done and said inside the cockpit. We don't have the superimposing right now.

Except control airspeed with the thrust levers.

@@jamesmurray3948 - But they needed the airspeed to maintain lift.

@@spacecadet35- Not at 350-400-450-500 kts they didn't. Not until nearing cruising altitude (30-40,000') is higher speed needed for adequate lift. The speed limit below 10,000' is 250 kts.

@@algrayson8965 - My response is simple. Even at nearly full throttle (thanks to MCAS) they could not generate enough lift to stay in the air. Lift is generated by Bernoulli Effect ( determined by using the Napier-Stokes equations) AND angle of attack (this is why aircraft can fly upside down.) If they cannot generate lift from Angle of Attack due to the trim issues, then the only other source of lift is by increasing the Bernoulli effect. This is achieved by higher airspeed.

@@algrayson8965 - It maybe, but when your only other option is crashing into the ground, pilots have a strange habit of prioritising problems. In a stall or sink your normal solutions are a) lower the nose and b) increase airspeed. Due to altitude a) is out, so what other solutions can you offer the pilot other than keeping airspeed up?

I think you are very close to the truth. The pilots probably didn't think about airspeed or perhaps they thought that the airspeed indicator is also wrong. Their lack of training caused them to panic and to crash the plane.

Michael Stuart Even between a 737-100 and 800 NG, beyond the handling characteristics, the differences are so huge that I cannot understand that a common type rating is possible...

Michael Stuart Your comments hit the heart of the problem.

This

Aerospace have fallen behind. They assume they are state of the art and space Age, in fact other industries and people of actually moved ahead of them.

Same here, what really blows me away is each and every cheap smartphone has a pretty accurate level sensor incorporated into it, why can't they incorporate this very robust ( compared to what they have ) sensor as a check. To me, it boggles the mind.

@@stargazer7644 you don't. You show a warning and disable it altogether. That's the issue here. Do you understand the fiasco now?

This is why Airbus has 3 sensors ...u need 3 to determine which is right based on the average of the other 2 matching

@@stargazer7644 The coding logic would be that if AOA1 does not agree with AOA2, use NEITHER and MCAS will be deactivated. MCAS is NOT a critical system.

Nicely done sir.

Hy

Boeing didn't consider it a critical safety system. Dual AoA inputs were an extra cost option.

The problem is, that they were lazy. They should have designed a whole new plane at some point, but they were not bothered and fitted an old one with unsuitable engines. And, they ended up with an unstable airplane which needed an electronic system to keep the unstability at bay, which they designed cheaply because of greed. They forgot about the rule, that unstable jet aircraft should have ejection seats. That is why unstable aircraft are called fighters. And the 737 is not one.

...And, the MCAS override/malfunction/wrong information warning system was an $80,00 option! Cheap bastards Boeing. I understand the Ethiopian and Lion Air did not have this feature.

@@bradjohnson169 there is no MCAS information warning system, only AOA indicator and AOD disagree options, MCAS can be turned off easily by hitting the STAB TRIM cutout switches

Sorry if I am wrong , then what does this mean? www.geekwire.com/2019/report-optional-safety-features-boeings-737-max-jets-will-offered-free/

.....and yet Mentour Pilot has acknowledged his full confidence in MAX. Go figure.

@@michaelpruski2281, I believe Mentour Pilot was saying that he would have full confidence in the MAX once the idiotic initial MCAS implementation has been fixed, e.g. by using BOTH AOA sensors before activating, by limiting MCAS authority and maximum trim travel as well as issuing reliable warnings when MCAS activates. Boeing has a decades-long reputation for designing safe and reliable aircraft, and they WILL eventually regain that now-in-tatters reputation by leaving safety and quality issues to the engineers, not management, but the cost will be great.

@@Halli50 Indeed. You are correct regarding Mentour Pilot statement! Thank you. Regarding Boeing.... 350 people are gone and they wont be coming back.

@Robin. Before the preliminary report, the speculation was the crew maybe did not cut off the electric trim, thus disabling the MCAS. Now that the report is out, fingers are now pointing to the throttle situation. Was that the cause of the crash? The answer is no. Would reducing airspeed could have helped with the manual trim? The answer is maybe. Even at 250knots and nose down, the forces on the stabilizer would have still been too great to overcome with the manual trim wheels. Or maybe they could have if the plane had more altitude, a luxury they did not have.

reddog 458 More testing is not what lacked here. This is a (major) design fault. The systems should be safe enough to not cause a fatal danger from any single component failure (AOA sensor here), and this is achieved by proper fault-tolerant design choices (such as redundancy, cross-checking systems, sensor coherence monitoring, etc.)

Thanks Mike!

Trim overrun situations have been possible since the plane was originally put into service in its original configuration on April 9, 1967. The elevator trim cutout switches have been in the same place for 52 years and the memory procedure for trim system overrun has been in place for 52 years. MCAS is just one of the possible root causes for trim overrun. The remedy is to throw the elevator trim cutout switch to "cutout." What these pilots failed to do is fly their airplane after they threw the cutout switch, not properly managing altitude and airspeed. What they should have done is what every pilot learns in ground school before he steps into a Cessna 172 or other learner aircraft. FIRST FLY THE PLANE. Then when the plane is in a safe configuration of attitude, altitude and airspeed, ONLY THEN troubleshoot the problem. These guys, with a perfectly controllable airframe, neglected to fly it. Holding attitude with yoke only, they should have reduced throttle to level cruise level, waited for the plane to settle down, then with attitude and throttle entered a standard climb to a safe altitude and established straight and level cruise there. THEN AND ONLY THEN, one of them could have easily adjusted the manual trim and it would become a routine flight from then out. Depending on management, the tower or the captain, they could continue their flight or return to takeoff field. Don't forget, someone threw the elevator trim cutout switch back on, to use electrical trim on the yoke, then left it on so MCAS could crash the plane. There is a 5 second delay between when you input manual trim adjustments and MCAS begins commanding trim adjustments again. Had the captain turned the elevator trim cutout switch back to "cutout" immediately after his adjustment after violating procedure by turning MCAS back on, he would have been flying well over Vmo, but he still would have had a shot at saving the day. All he had to remember was that throttle....

@@RockinRobbins13 This guy gets it

@@robroilen4441 I'm not saying the system couldn't be made safer. I'm saying it's safe to fly as is.

@@RockinRobbins13 Agreed. I see a lot of people regurgitating the latest half-true mainstream media updates and calling for software fixes without addressing some really common sense flying practices that simply were not used in this accident. Sure, refine MCAS, but teach pilots to rely less on automation.

@@robroilen4441 _"Sure, refine MCAS, but teach pilots to rely less on automation."_ There's a reason lots of commercial pilots are also sailplane jockeys. Pure stick and rudder experience is golden, and it would have saved this Ethiopian Airlines plane. Yes, connect both angle of attack sensors to MCAS and the attitude readout from the normal avionics too. Let MCAS compare numbers and make rational decisions, alerting the crew when it sees a discrepancy. Tone down MCAS' power so that at full strength, pilots can still overpower the MCAS trim with the yoke. Of course that is speed dependent. At 500 knots, it would take very little trim before human muscles on a yoke would be overpowered. Have to make this work for normal flying speeds and aerodynamic control surface loads. If the pilot exerts more than a certain number of pounds force on the yoke in the up direction, let MCAS cancel and give the pilot control of the plane. With competent piloting, this could save lives. But we can't lose sight of the fact that no plane will ever be so safe that a sufficiently imaginative or determined pilot can't crash it. We have to get rid of the attitude that if a plane crashes we need to cripple the Airline manufacturer. It isn't automatically their fault. It isn't Boeing's fault here. They did everything, disclosed everything they knew to Ethiopian Airlines, gave complete instructions, warning that a faulty attitude sensor could cause a trim overrun, detailed the steps to compensate and instructed the airline to insert the bulletin in the Flight Operations manual. And it instructed the head of 737 operations for the airline to make sure all pilots were briefed on the seriousness of the situation. This garbage about Boeing not caring about airline safety, that they purposely rushed an unsafe airplane to market is slanderous. It's wrong. It's evil. Only live, breathing people buy airliiners. When is the last time a dead victim of a crash bought an airplane? The Preliminary Accident Report makes it very clear that Boeing cares about the safety of pilots and passengers who fly their airliners. They issued the bulletin before the FAA had any input at all in their zeal to notify customers of a situation that improperly handled could kill. When news media around the world stuff events into their agendas of anti-Americanism, anti-capitalism, anti-corporations, anti-government, whatever their enthusiasm, they do a grave disservice and sully the memories of those who died in this tragic accident. Nobody wanted this to happen. Let's bury the hatchet, ask the tough questions and make flying safer. But remember: no airplane is so safe that a sufficiently imaginative or determined pilot can't crash it. The only completely safe option is to ground everything that flies. And that would kill thousands, maybe millions of people.

My understanding is the MCAS only responds to a single sensor, and it might have been the one that was bad. That's one of the things that's wrong with the system. But deciding which one of two is wrong could be very problematic. It seems to me three or more sensors are in order. I have three themometers outside the window on my back porch. One is electronic, one is a bi-metal coil, and one is alcohol in a glass tube. Rarely do they fully agree.

In a refinery in critical systems, we have 2oo3 or 2oo2 - 2 out of 3 or 2 out of 2 before a critical safety device is activated. Seems they would have a similar voting in criteria on aircraft safety systems such as MCAS.

Internet Privacy Advocate which is related to my point: an excessive rate of change for Alpha, even on a single AOA sensor, ought to disqualify that sensor input to the flight control computer. Certainly it would have been preferable to have Alpha data from either AOA sensor available to the computer and to have the computer sound off (loudly) in the event of excessive rate of change or difference in absolute Alpha value. I wonder who among the Boeing engineering staff is going to turn out be the Roger Boisjoly of these accidents.

The architecture probably provides ‘fail safe’ stick-shaker operation at the expense of an erroneous high AoA input, which I assume is part of the high reliability requirement. Failsafe for stick shaker is opposite for MCAS.

Lee M I don’t think the old legacy systems architecture supports fault tolerance very well. It’s only duplicated not triplicated but pilots must decide what is working and what is faulty. Also if you get wire break on alpha sensor you want erroneous high reading for failsafe stick shaker and erroneous low for MCAS activation. Whoever had to program this pile of dog shit would’ve had their work cut out for them because the systems architecture wouldn’t support the kind of automation and failsafe fault tolerance required. I doubt 2oo3 is supported as configuration of I/O but would require explicit programming.