737 Max UPDATE 20 March 2019 

UPDATE to the Update from AvWeekly aviationweek.com/commercial-aviation/faa-reviews-enhanced-max-flight-test-data?CPEN1000000907970&elq2=7b24c0887f88426098a9f69399830ffc%20FAA%20Reviews%20Enhanced%20MAX%20Flight-Test%20Data

"Turns out I can talk and fly so they made me an instructor" Good line.

As a retired airline pilot and mechanic, I have to say this is the best and most complete explanation of the potential root of these accidents I've heard yet. This sounds like a simulator training session from hell. With pilots having multiple symptoms that they don't realize are related. Much of our simulator training serves to train our muscle memory to react instinctively to the most likely sudden events such as engine failures. When presented with a novel malfunction, we have to rely on our knowledge of systems to even know where to start looking in the manuals. Unless the aircraft annuncitates the nature of the problem, valuable time is lost trying to identify it. I spent most of my career in DC-9s, which didn't have the pitch up tendency when adding power. I learned about it on the 767.

FYI, Juan, you've managed to gain the respect of five former (all long-retired) avionics support engineers, and industrial engineers, myself included, all who've supported the production of avionics systems for at least ten years. Thank you for providing a well balanced, honest view of the situation. The news organizations would do well to adopt your methodology.

Juan, this has to be the most fact-filled and technical explanation of what happened to these two aircraft and you were able to put it out there in language everyone is able to understand. Even the NTSB couldn't do a better job. You are a truly gifted journalist. I eagerly await all of your reports. Keep up the excellent work.

I'm a non-pilot and have been following this closely from many sources. This video was just outstanding!

40 years in the aviation business as a research and development aerodynamics engineer, airline operations engineer, and engineering test pilot on every category of aircraft from small bug-smashers to jumbo jets. While all of us can go on for hours discussing system design, operational details, and lack of pilot awareness and training, the fundamental underlying cause of these accidents was schedule and budget driven by short-term business goals and stock prices at the expense of comprehensive system design and testing, coupled with limited resources within the FAA. To avoid these kinds of accidents in the future, the FAA needs more resources and the manufacturer's ability to self-certify needs some serious critical analysis and oversight. Very nice video, sir. Well done!

You put in 10x the effort of mass media to get the story straight. Thank you for the time and great videos.

Again The best pilot reporter ever ! Thanks Juan

Having watched your videos on the MCAS. My first thought after I saw the news of the last crash was “that must have been a MCAS problem why didn’t they just turn off the trim stabilizers.” I am not a pilot. I learned that from you. You have by far the best technical explanations for complex problems that I have seen on you tube.

I'm genuinely impressed with your resume. I'm in a medical field and was under the impression that pilot hierarchy progression is fairly straight forward, however it is now obvious that i was wrong. Having to undergo training on such a variety of aircraft over the duration of your career is truly impressive.

I wish your analysis was more widely publicized. I realize mainstream media thinks us regular folks are stupid, but we're not. Again, many thanks for educating us in such detail.

The idea of a 3rd pilot in the jump seat having a "big picture" view of things is much like a coach watching his team play. They're dealing with specific things happening and their own involvement, but the coach tries to see the trends and thinks of adjustments to make. It's a pretty good analogy.

I'm not a pro but I appreciate all the details and time you put in these videos. We are lucky to have an expert share your expertise.

Thanks for the 'refresher' on engine placement on the strut. I can't believe they only used one AOA signal! Didn't know what MCAS was until your explanation. Excellent graphics. Well Done! Lousy way to review past training, but a great service none the less.

The umpire description of sitting in the cockpit is more accurate than I’d like to admit. Commuting for work at the airlines has taught me how important it is to take a step back and reevaluate my SA. I can’t even count how many things I’ve seen missed while sitting jumpseat, and it made me think of how much I’ve surely missed. And as far as startle factor goes, I couldn’t agree more. Being 2000 afe and having a trim run away is scary enough, let alone the wicked nature of what an mcas failure appears to be. I’d like to think that I wouldn’t be lawn darting in that situation but I think given the situation the odds are definitely stacked against the crew. Rip. Thank you for your updates, it’s increasingly rare to find a channel with such thoughtful coverage. You have earned my subscription!

Juan, being a former resident of Paradise with lots of family that still live there I originally started watching your channel because of your reporting on the Oroville Dam. Then you're excellent reporting on the Paradise camp fire, in your true Juan style it was absolutely excellent I may add. As a civilian with absolutely no pilot experience I wish to commend you for your professionalism, extensive experience as a pilot and your detailed approach to everything you do especially being a pilot. Before I retired I did spend a great amount of time for business as a passenger in my career. Always knew that the pilots were true Pros. You have to be in the top of your field. Thank you for providing us your extensive background as a pilot. Getting to know you on your channel the last year-and-a-half has truly been uplifting in everything that you report on. With so much fake news and bias in our news media you bring the true facts to an issue. Thank you Juan it is greatly appreciated.

I started watching you on the Oroville disaster since then have followed you these air crashes that you explain do a lot for the people like me who are just normal people that are not in this feild , thank you for what you do will always read your comments very informitive.

Clearly explained so even a non pilot can understand the basic problem. Thanks very much for this spot on video.

At 11.25 sitting between the pilots on the centre jump seat -that's what we flight engineers did. It's a great overall picture. Bring back the third set of eyes!!!

Excellent presentation. I wish my ground school instructors had your linguistic and technical skills. Retired pilot - DC-9, B-727, B-757, A-320, A-330.

The jump seat pilot who prevented a crash reminds me of the late, great Denny Fitch in the Sioux City Iowa disaster. His presence was widely credited with the DC-10 landing well enough to save many lives. It is unfathomable that one Lion Air crew could save their jet from disaster yet not pass the information on to the next crew and indeed the rest of the fleet. If true, this is a cardinal sin. Of course Boeing deserves a ton of criticism for their bungling, too.

The C-130 is an amazing aircraft. In 1998 I was stationed in Oman as part of a detachment flying C-130 supply missions across the theater for Operation Southern Watch. At one point we landed in Doha to unload a generator. When we got the go-ahead to return to Oman the metal gear on the starter for engine #2 snapped off. After waiting around for a few hours we eventually got approval from Headquarters to do a windmill start. I was a young ammo troop at the time and didn't know much about the C-130 so it was pretty scary. But it started right up about halfway down the runway without any issues. That's versatility!

I fly a Dodge pickup, but your explanation gives even a ground pounder a good idea of what happened,thank you...

Yet another excellent report, Juan! Keep up the great work! You provide a very good description of the tunnel vision when faced with handling an unexpected situation. I'd add that not only is one's "picture" restricted in lateral/subject scope, but also in time. One's time horizon collapses, so one cannot see very far down that tunnel! The first time I was faced with an aircraft malfunction, I experienced this effect. (Before that incident, everything that had gone wrong during my flying had been my fault!! So that was the first mental hurdle!) I'm a low hours (and now long lapsed) private pilot (350 hours in total, and less at that time). I had a pitch trim malfunction in a TB20 (Trinidad). It was not even a runaway, it had simply jammed. Even so, when climbing out, as I unthinkingly routinely cleaned up the aircraft, increasing forward control force was required to keep the speed from falling too low. Also routinely, my thumb was planted on the electric trim switches, but this was having no effect. As you describe, a pilot who is not flying maintains a broader perspective. Luckily my front seat passenger was an instructor and examiner, who immediately recognised that I had a problem. After we'd made a fairly quick diagnosis of the problem, he asked me whether I wanted to turn back, which I did. Later when we discussed the incident (which, by the way, was caused by a riding turn on the cable drum), he asked me about the decision to go back and whether I'd already thought about that. My response was that I had not thought that far ahead!! Before takeoff, my time horizon had been approximately the duration of the planned flight, about an hour and a half. That fault caused my time horizon to collapse, probably to less than ten seconds!!

What a resume! You can not believe how much I look up to you Juan! I myself: 26 years old, belgian, architect and lifelong aviation geek. Only a year ago I finally made the decision to start flying gliders, let’s see where this takes me. You have a fantastic channel and you are an amazing reporter. Thanks for sharing your knowledge!

As someone who designs and troubleshoots industrial automation control systems, I see 3 problems here, 1 of which doesn't seem to be directly mentioned very much, which is unreliable AOA sensors. None of these incidents would have happened if the AOA sensors were not faulty, so they need to find out why they are failing, and correct that issue, because this is an unacceptable rate of failure indicating a poor design or testing process. Second issue is lack of user training after a material change in the function of the system, because the scope of the change was underestimated. The third, and most important, and most egregious error is in making the control logic not fault tolerant. I run into this a lot when I am called in to correct a system that is misbehaving, and usually I find that the original programmer did not plan for faults, and assumed that all inputs and outputs would be reliable and within a certain framework. Basically, you have to remember that a logic control system is Infinitely creative. In other words, if you tell it to perform a certain function, you have to think of all the possible ways it could be triggered to perform that function, and program out all the ones that you don't want to have happen, and try to predict all the possible failure modes, and have a plan for them, because if you don't, the system is going to respond, because that's what logic systems do, they respond according to the inputs, with no regret. And if you simply do a textbook "if Switch A is activated by Part B, then perform Action C", how are you verifying that it is Part B that is being sensed, or that the machine is in a safe condition to perform Action C? For instance, one machine had a large frame that moved back and forth on a track, and it had a limit switch at each end. It was programed that if it sat on the extended limit switch for longer then 5 seconds, it would power it up to retract it to the safe home limit switch. This was done as some sort of fault recovery routine, with the designer probably thinking that he was really smart coming up with this to make sure that it would default to the home position. The problem was, he didn't look at anything else before acting.. The routine was simply that if the extended limit switch was tripped, the unit would retract. It didn't look at whether the machine cycle was active, or whether the Home limit switch was already tripped, or anything else. So every couple of days, the unit would randomly retract past the Home limit switch, and would over travel and get wedged in before things would trip. And then it took some disassembly to get it back where it should be. I set a camera up recording the input status on the controller, and the next time it happened I saw that while the system was idle with the home limit switch tripped, the Extended switch input would come on and crash the unit. After I found the routine mentioned above, I started testing switches and checking wires, but the switch was brand new, and I couldn't locate the intermittent short that I suspect was in the wiring, so I added a command that it would only run the routine if the unit wasn't already Home. (they were going to dig deeper and find the short in the wire, but the system never had that problem again because I had made it more aware of the rest of the inputs.) Another system I had fun on was an automatic truck wash (like a car wash, but for semi trucks, and more complicated!) It had been programed to assume that if a photo cell was blocked, that meant that a truck was that far through the wash, and would activate whatever components it controlled. This is great as long as everything is clean, but when soap scum or hard water deposits start building up on the sensors, residual spray from the 50 horsepower oscillating pressure wash nozzles is enough to trip a partially occluded sensor, activating stuff after the truck was gone, and sometimes it was the sensor that activated the spray, leading to a constant cycle. Fault tolerance was created by including the previous sensor in the logic, so that if the previous sensor had not been tripped, it would not activate, ensuring that things happened in the right order, and it would take multiple consecutive faults to cause unwanted behavior. In this case, it sounds like there was no thought to what would happen if the single sensor failed, so no checks of other plane systems, no checks of what the pilot input was, no comparison of redundant sensors, just a simple single line of code, "If AOA exceeds Angle A, then activate Stab Trim until Angle is less than A". Simple and stupid, and works great, as long as all of the inputs and outputs are trustworthy.... It almost sounds like it was a rushed afterthought, and it either was programmed by someone that didn't understand Fault Tolerance, or it was the first rough draft of the program, but the guy was put on something else, and no one completed it or it was rushed to production. They may have also justified it as not needing all that extra complexity, because if there was a fault, the pilot would know to shut off the Stab Trim because that was already a memory item, so it didn't need to be fault tolerant. If I were in charge of redoing it, based on the information I have, I would set it up kind of like how a lot of autopilots are, to fail neutral. So it would look at both AOA, and the pilot's input, and the Stabilizer position, and would take action based on which ones agreed the closest, and was the least severe control input. And then at the same time, would alert the pilots that there was a sensor failure and that they needed to take charge. For instance, if the right AOA was within normal readings, and the pilot's inputs matched the right AOA, and the stabilizer position matched both of them, but the left AOA said the world was ending and we are all going to die, then it would pat Marvin the Depressed Sensor on the head and give it a Valium, and fly according to the right sensor. Of course, a big part of fault tolerance for something like this, is training the pilots in how to respond to faults, how to recognize them, and give them the information they need to spot them. For instance, have an indicator so that they know that the plane thinks they are stalling, instead of just taking action without informing the pilots. I would be really interested to hear the story of how this ended up like this, who dropped the ball and what the reasoning was, but I suspect that will not be made public, unless it comes out in the lawsuits. But bottom line as a control system designer, this system was not properly designed and integrated into the system and flight crew, and that is the ultimate cause of these crashes, even with the aspect of the poor maintenance culture before the first one, and possibly bad training for the second one, because the technical side could have been so much better and taken those into account.

I found your channel back when you first started describing the Oroville Dam problem. Just wanted to say how much I have appreciated your very clear reports and your commitment to getting things right. These latest explanations of the 737 Max crashes and MCAS are excellent. Thank you for all you do to get good information out there for all of us. And, as a flying enthusiast, I love the way you've used the Mighty Luscombe in your channel. Keep it up!

As a non pilot aviation enthusiast I have to say this is a brilliant explaination of the MCAS system and how it would appear to have caused the two 737 MAX crashes. I had picked up a lot of the information from several other places but this makes it clear and understandable to the layman. Thanks.

Thanks Juan...!! Just the FACTS Here..!! Since they found the jack shaft at the end of its travel, in the full nose down position, obviously the pilot and FO did not shut off the Stabilizer Trim system or manually override it. You can see there are switch lockouts at 1:13 that need to be pulled out and then you can turn off both switches. I bet this will be a huge lesson modification for pilots when doing annual Simulator Training for this kind of 737. as well as Boeing making software mods to the MCAS.

I am a retired biomedical/electrical engineer and I can say I've been there and done what I think you are describing-- fix a hardware issue with software. It can be done but you're on thin ice. As to why use one AOA sensor when two were available, words fail.

You and Mentour are the best Pilots in the world when it comes to explaining things with no BS and undestandable to both Novices and laymen alike

What a tragedy. It takes just seconds for the pilot flying to call out "Stab trim cutout switches...CUTOUT" and the pilot monitoring to whack those switches. My company would probably listen to the CVR (they copy and archive 800 hours per plane, audited regularly) and give the pilots a rash of hassle if they don't call "QRH Runaway Stab Trim" first. As you say, that procedure doesn't fit an MCAS malfunction. Figuring out what's wrong delays remedial action enough for that trim jackscrew to go to the full nose down stop. That Lion Air jumpseater, who helped save the prior flight, should never have to buy his own beer for the rest of his life.

We couldn't get 1/1,000th that type of information on the mainstream news! Appreciate you taking the time to thoroughly explain this MCAS system. 👍👍 Sure makes me wonder if Boeing will be sued big-time by the families of crew and passengers of those lost thus far. From where I'm sitting, they engineered a death trap, especially by not FULLY explaining this system and how it functions. I recall not long after the Lion Air disaster, American pilots were asking alot of questions about this system, and weren't getting very many answers. Seems to be a trend in manufacturing today, where the manufacturer wants to keep everything secret. That may work for a while in land based machines, but there's no "do-overs" in aircraft at any altitude, especially lower. Thanks for the great insight! 🍻

As a former C-141 and Air Force 737 pilot, I have to say....you nailed it.

I've been a subscriber since the Oroville disaster and since then you have offered a front row seat to the spillway reconstruction, then Paradise fires last year, and now these airline disasters. Truly amazing commentary. I must say that this overview is providing an even more damning account of Boeing's pure neglect in the development of this aircraft than is being reported elsewhere, and the reports elsewhere are already pretty damning. They are in a LOT of trouble with these catastrophes, and the US government and FAA oversight comes out looking awful as well. Yikes.

Thank you very much for the update sir! I really enjoy your videos! 👍🏻🧔🏻

I feel as though I have just been in the classroom of a very good professor. Thank you for the lesson sir. As far as I'm concerned, you deserve tenure. And a raise. ;-)

0:47 - WOW lucky they had the jump seat guest on board. Great report as always Juan. Thank you.

Thanks blancolirio, for explaining several points for which I needed clarification and explanation...! Re: Redundancy of AoA sensors: It is my understanding that Airbus uses 3 AoA sensors, so that in the event of a single sensor failure (the most common scenario) the flight control system will use input from either of the two sensors that AGREE with each other, as a failure of two sensors at once has the LEAST likely probability. However, two included sensors are enough if MCAS is not flight-critical, and if it shuts off if the two sensors disagree, to be repaired later on the ground. However, if the MCAS is critical to avoid stalls in the 737 MAX then 3 sensors installed with isolation circuits (so that a 2 sensor failure is least likely) would be the safest. At this point, we have to acknowledge the comments of Sully Sullenburger that it is still important that cockpit crews can fly aircraft manually when systems such as MCAS fail, and are trained thoroughly on how to disable non-functioning systems. Also, the Seattle times has pertinent information about the dialogue between the FAA and Boeing, with regards to the safety certification of the MCAS system, which is still relevant: www.seattletimes.com/business/boeing-aerospace/failed-certification-faa-missed-safety-issues-in-the-737-max-system-implicated-in-the-lion-air-crash/ and a rephrasing of the Seattle Times article article from nymag.com, regarding Boeing self-regulation: nymag.com/intelligencer/2019/03/report-the-regulatory-failures-of-the-boeing-737-max.html I hope Boeing gets it right before these planes fly again; not just for their bottom line, or for their shareholders, but for the 346 who will never fly again!

Excellent discussion of the facts to date. I've followed this closely being an engineer. The design process for the 8 and 9 Max, from all I've heard and read thus far, appears to have had a serious deficiency in the Single Failure Analysis, including software hazards analysis, and failure modes and effects analysis of the MCAS system design (hardware and software). No way a single failure (AoA sensor) should have led to a catastrophic loss of control of the aircraft. And someone decided in software that the pilots control input via the yoke should not defeat MCAS? And no one thought that MCAS action should be limited? Terrible, terrible design flaws in the software. And lets not forget that now there have been 2 failures of the angle of attack (AoA) sensors on the Max planes - that component almost certainly has a design flaw as well, but no ones talking about that, at least publicly. Another problem is the design itself - engine and engine mount changes. If you have to develop software to overcome an aircraft control issue for stable flight, you just might have a shitty design. And last but not least, these changes were significant enough to require training for the MCAS changes, and clearly addressed in the POH and quick reference. This should have been treated as a new type aircraft based on the handling characteristics of the re-design and the required training provided. But everyone wants to save money, so Boeing and the FAA determined it was not a type change.

Excellent video, Juan. I am an experienced commercial/instrument pilot keeping up with industry developments. In your well paced, informative video I learned at least four new concepts relating to this MAX 8/9 situation, a rare grasping of knowledge for me from an Internet video. Congratulations for your fine service to the industry and flying public.

This has to be the best 737 MAX explanation video to date. Time to bring Boeing HQ back to Seattle and replace the bean counters with engineers; I say. Nice to hear your extensive flying background too; what a fascinating extensive career you've had. Thank you!

This is the most thorough discussion of the whole problem I have seen yet. Thank you. I listened to the whole thing. One point of controversy still being discussed is whether putting these more powerful engines on an old airframe, requiring (for some reason) automated trim adjustment, is in itself a design error. I am sure that MCAS can be made safe, but should it have been done at all?

I'm really enjoying the level of information you are providing in these videos. I don't normally comment because it's already been said, but felt compelled after this video. Well done. I found your channel when you were talking about a KTM dirt bike, but I find this information very interesting. Thank you.

Hey!!! Thanks for the unexpected rundown of your resume! I was actually curious as you had mentioned Air Force, but I had never heard you elaborate. Best Wishes and Best Regards!

Great video and technical briefing Juan. Thx for your military service and your outstanding results of keeping all of us acqurately informed. Safe Travels to you and yours.

Best, most detailed description of the problem I've come across. Great job! Kind of funny that now just about every nerd knows how to disable MCAS.

Juan, I have been looking all over for a comprehensive intelligent overview of MCAS system including engine history and finally you did it! Thanks so much, an outstanding job!

I have a full certification on a canoe, but,, I am very well read and have remained interested for a lifetime. Your description of cause and result I find faultless. I found and viewed this video because I already respected your skills and ability to explain. Thank you. And you did touch upon it,, the MCAS is more than just an assist and warning system. It is capable of over ruling a pilot if faulty data is entered, without redundancy. This touches upon exactly what I have been seeing/surmising. If I understand correctly, you will know, the original to the MCAS, the pilot could disconnect the system by pulling the yoke to full back,, a highly intuitive move that would simplify recovery and gain precious time. Time to then pull out the loose leaf book and run a check list while the plane is out of danger and flying under normal manual or autopilot. The MCAS is the first system I am aware of,, you likely know of more,, that can actively over ride a pilot and control the plane into something undesirable, dirt. The intuitive response of yank the yoke all the way back, was, and should be the the first line of disabling the system. Not just mute the system, or enter the redundancy of both AOA vanes, but cut out the stabilizer computer control,,, AT a minimum,, long enough to find and run a check list. MCAS is not a stick shaker, not an announced warning of "Too slow.",, or "Pull up.", it is not assistance or advisory. It is not a safety system. It IS a pilot cut out system. It stands between a pilot and his or her control of an aircraft. And that is fundamentally wrong. Even reprogrammed,, pilots should refuse to fly it.

Thanks for that crystal clear explanation of the MCAS system. I'm frankly staggered by what seems to have been an inept implementation of this system. I thought that EVERY automatic system had to be redundant and also handle what to do in the case of conflicting sensor information. Doesn't Airbus have a 'best of three' for precisely this kind of situation? It looks like Boeing have really dropped the ball on this one by not only making a fragile system but allowing it sufficient power to overwhelm the pilot's inputs. It's hard to know how their customers will ever have confidence in this system. This is a big enough issue to cripple the company in my opinion.

I found you during the Oroville spillway crisis and have followed you ever since. Your excellent unbiased reporting, knowledge of the issue, and clear explanations are a rare combination that you have. I thoroughly enjoy your reports

Outstanding, Juan. I appreciated hearing a bit of your history, as well. Thank you!

Excellent Job! The wife and I understood it the first time. The Umpire seat has a different perspective also, good point. Very well explained to civilians.

Excellent video and great information. I am surprised that the computer controlling the automatic control system would not automatically shut off or decrease its adjustment when a pilot has reversed the automatic control adjustment two or three times in a row. Logic would prevail that the pilot should have the final control! Especially if there were two pilots making the same corrections against the automated system. Sometimes computers do not make the right decision because of bad input from instrumentation. I have 32 years of PLC programming experience developing automation controls for a crude oil pipeline.

Juan, an absolutely clear update on what is progressing on the 737 Max situation. As a former military pilot and instrument instructor, I can state your clarity on the issues is outstanding. Thank you.

Very interesting as usual Juan. You almost made me feel like I was in the cabin with the pilots. Thanks for telling us about your life too, lots of respect for you.👍

Great stuff, Juan. My wife and I are pilots, we sat down and talked about this one for an hour or more. I think we have it: To keep cost down, airline manufacturer company modifies a plane with new efficient engines that have the side effect of causing the plane to pitch up. To keep the plane flying as close to what it used to fly like, you add a little system (mcas) to counteract this pitch up issue. If you didn't keep the plane flying the same as it's previous model, it would cost a ton of money to retrain pilots because it could even be consider a new type aircraft. So they add this little "minor" trim device to counteract the extra pitch up so they don't have to label this plane as a new plane/type, essentially. RIGHT? Failure happens because of inaccurate information from the angle of attack indicator/electronics reading a high angle of attack relative to the wind and the jack screw positions the horizontal stabilizer to put the plane in a dive position. At this point, full movement of the elevators can not negate the effects of the horizontal stabilizer position. (and yeah, one fix of that could be just to limit how far it can pitch the stabilizer and still have the elevators be able to overcome that aerodynamic pitch) How did we do? We think that the extra pitch up issue must be significant because all pilots would know how to control the nose of an aircraft as you climb out. That is fundamentals of flying, day 1, climbing out - no new training needed. However, again, we think it must come back to keeping that plane's flight characteristics as close as they can to the previous model ..... to avoid a new type certificate.

We have a friend whose son joined the USAF following in his father's footsteps, had much the same career as you although he is still in the AF & flying C130's. Always enjoy your videos. Thanks for making a foreign subject seem simple & logical. ~ from Cut and Shoot, Texas, Richard.

do you think Boeing knew? ignored advice by engineers? the information I've been exposed to about the dreamliner makes me think so. I've just discovered your channel and I've gotta say, you have explained every aspect of all the angles, see what I did there? better than any other person tv show, reports and the ntsb. thank you so much.

I am surprised that the MCAS could overpower manual override without disabling the system. I would think that in an emergency, you may not have time, or the presence of mind, to flip the switches as you are trying to correct things, and to have the MCAS be all that powerful seems like a bad idea. Also, why is the system relying on one sensor without redundancy? That seems like a bad design choice also. Thanks for the outstanding explanation!

Thanks again Juan Juan, would you be interested in my recovery and survival of an total elevator disconnection at 50 feet after take of in a BE58..?? Hearing your thorough and comprehensive explanation has reminded me of the terrifying low altitude fight for survival that I went through for 45seconds and crashing 1.5 kms from takeoff.... Aircraft was totally destroyed but the cabin was intact and we all survived with no injuries.

Juan my background is Air Force flight engineer 22 years. 121ground instructor on the 737-200-300-900-max. 29 years. Everyone is talking about MCAS and then describing it to 800 SMYD system. My Manuel’s don’t even have a description of the MCAS system in it. I don’t know how the system actually works, I haven’t seen a schematic nothing on the max system. I can only compare to the SMYD system that is described in the 800 manual. How do I train pilots when I don’t have the the description of the max MCAS system. Thanks for your videos on the subject. As flight engineer that was my job to be the 3rd set of eyes in the cockpit and run the systems maybe we need that redundancy of the human kind.

as an A&P this is BY FAR the best explanation I think I have ever heard about anything! outstanding!

Great videos - many thanks! Your comments about the "third seat" perspective remind me a lot of the unique help the jump seat pilot had on the 1989 Sioux City IA UA crash. His help wasn't the only thing that saved a lot of those folks, but it did help a lot (if I remember correctly, he was also a trainer). Coming at this from an old IT perspective (having worked in silicon valley and had friends who were programmers for Boeing back in the 90's), this is really a very sad situation. Getting feedback from only 1 sensor, no matter how well it's made? There's a lot here to be unhappy about. I remember reading professional software design journals back in the 90's that detailed software design errors that crashed a few aircraft of that era. Some were horrific losses of life like this.

I can see you were an awesome instructor. You told us everything thank you. Boeing will just have to admit the mistake and accept responsibility. Replace top management immediately and hope the customers that buy this Airplane forgive Boeing by not canceling anymore orders. Condolences to the families of the victims. Could not have come at a worse time for Boeing when Airbus is doing well with their new Airplane. The FAA is another story and should be held accountable.

Seems the real problem is the overall design of these new aircraft affecting the flight characteristic thus requiring the mcas system to control it. Not just the MCAS. Need to junk these aircraft and go back to the dwg board. Won’t happen though.

One of your best Juan, thank you. So good to get these factual reports from someone with the amount of flying experience you have. First thing I learned about when I got involved in avionics was something called dual redundancy. I was thus quite surprised to hear you confirm that Boeing took the input from only one AOA sensor. Interesting points you raised about the 3rd/4th pilots wider view too, that's something us non flyers would not have considered. Good to see the subscriber count zooming upwards - keep those wackadoodle trolls out, you're doing a grand job.

I well remember flying the old -200 series with the "salami" engines slung directly under the wing. Very nice explanation of the basics of MCAS.

Doesn’t or wouldn’t Boeing have experienced pilots working with the engineers who designed this system to brainstorm all the potential problems that could occur in flight before putting a system like this in the cockpit? ....man that was some wind and rain. Excellent analysis.

You have done a superb job explaining these latest crashes which is a bonus. I originally started following your updates on the spillway and never realized your flying background, quite impressive I must say.

Thank you Juan. I appreciated Mr. Sullenberger's statements regarding the Boeing/FAA possible, (or likely) conflict of interest also. It's a nightmare situation, and I'm sure it's hard on most, if not all, commercial pilots. My best to you and your loved ones.

Excellent report as always Juan. Factual, informative and no "sky is falling" hypothesis statements. Wish the big news agencies had your level of professional journalism.

Started following you since Oroville Dam first cracked. I appreciate how informative you are about all these matters from airplanes to wildfires to infrastructure.

My dad's first plane was a Taylorcraft back in the late 70's. He loved that thing. Puts lots of hours on it and it was the first plane I ever flew. He finally sold it to buy a 172 and later a Bonanza for family flying but always regretted selling the Taylorcraft. He's 82 now and lost his medical because of a heart attack, but he knows exactly where the Taylorcraft lives. Has followed it around all these years. His health is good now and occasionally he'll talk about getting a sports license and buying it back. The owner doesn't want to sell and I'm not sure dad is all that serious about it. When he had the heart attack and subsequently sold the Bonanza, he had around 6,000 hours and I think some of the fun was gone at that point. But the passion returns occasionally now that he hasn't flown for some years. And it's the Taylorcraft that rekindles it. Great video and good recap on the update. Thanks for sharing!

Appreciate your "Pilot's Perspective" on this and the background on your years of experience. Seems like Boeing has made a ladder of mistakes that have added up to 2 disasters that could have been avoided. As always you tell complicated stories in a very clear and engaging manner, Keep up the great work.

Juan wanted to thank you for the straight forward and thorough description of the issue! Easy to follow!

As a mechanically inclined non aviator your vids make it easy to understand some very complex issues

Excellent very informative report Juan! You answered the simplistic thought I had of why didn’t the pilots simply cut off power with the Stab Trim Switches. You gave a good perspective on the nature of the urgency of what’s happening, the conflicting information they’re getting, and the limited time to react. Thank you. Keep up the great work.

Great perspective from a very experienced pilot. Mainstream media doesn't take the time to explain what a pilot will experience in such a situation so low to the ground. I flew out of Bole' on way to Cape Town a year ago on Ethiopian. Very experienced, professional crew. Taking off at 7,600 feet was interesting as well. The fatal Ethopian flight never got more than 1,000 feet off the ground. Imagine the responses and the physical exertion that the pilots had to go thru even if they knew how to shut off the stab trim. I explain it to folks by saying, "imagine if you are on a mountain road and you approach a left hand bend and when you turn left the car overrides you and turns right. And the harder you turn left the harder the car overrides to the right. The entire time the car automatically starts accelerating. Would that get you confused even though you know you simply need to turn the car off or hit the brakes?" Thank you.

Thank you for taking precious time to explain these unnerving accidents. For those of us, just civilians who have to fly time to time, you bring us some understanding ,peace and more confidence in our pilots.

Been waiting for this one! Thanks for all of your great videos.

Thanks ever so much for the most cogent analysis and explanation of the 737 Max issues that I've been able to find. As an old RC-135 guy I've always been partial to Boeing aircraft but the Max problems have shaken my "if it ain't Boeing I'm not going" opinion just a bit. Your latest update really clarified what's going on from a commercial pilot's 'no BS' perspective.

Juan, Started following you during the Orville dam spillway emergency, that was very informative, thank you. I have good mechanical knowledge both applied and theoretical thanks to my career as a industrial HVAC tech and through many hobbies. I've also had a lifetime interest in aviation and aerospace, although not a pilot , have had some Cessna seat time. That said: Your doing an outstanding job explaining the details and situations regarding these incidents. The average person should have a better understanding of whats really happening after watching your videos. The news media is generally clueless and just repeats talking points with no understanding of what there reporting. Thanks for great work your doing. I've made a few videos and know how much time and effort it takes. Again Thank You, Please keep them coming! -Dean

THANK YOU Juan, I'm amazed there is only one single analog AOA device, when an electronic accelerometer/gyro could be a quick, tiny, and easily installed backup. "Accelerometers in mobile phones are used to detect the orientation of the phone. The gyroscope, or gyro for short, adds an additional dimension to the information supplied by the accelerometer by tracking rotation or twist." I mentioned a software conflict before, and a redundant digital system could at least set off an alarm if there were conflicting input data, especially if the data were counter to pilot control(s) input. I'd also recommend such a conflict be programmed to immediately return control of the aircraft back to the pilot(s) in the event of such an alarm. Thanks again for a wonderfully detailed explanation, including the "Startle Factor" I bet few had realized would be a seriously significant factor in handling such an instantaneous control conflict, "This aircraft is NOT doing what we're telling it to do!" And, the 3rd seater saw the solution immediately, simply because he wasn't all that startled. Indeed, completely overlooked... (I'm not an engineer, but I play one on guitar.)

My son and I was watching your previous episode. I mentioned to him, If I ever needed a pilot I hope it's that guy. I knew you seemed so experienced and knew you had the right stuff. After the explanation today with your background. It solidified my opinion. Juan love the episodes and appreciate all your hard work.

It’s hard to visualize the terror the crew experienced when struggling with the MCAS. Fear definitely compounded the difficulty of coping with the emergency.

Exactly right. The third nonflying member is like being a flight instructor. It’s easier to critique the student than it is to fly the plane yourself.

Thank you for providing more detail on the MCAS issue and explaining in greater detail what the pilot’s point of view is during the event as it certainly helps to answer some of my questions and addressed some of the aspects that had puzzled me.

Really glad that I came across your videos. Excellent presentation. Thank you for taking the time to help us understand the ongoing situation. Best, Andy K.

Great update. Figured it might be a trim problem from the get go. Appreciate the detailed MCAS explanation.

Great segment Juan! I'm an aeronautical engineering for almost 40 years and who works for a major Boeing competitor. This explains much more about MCAS, how it works, the evolution of the 737 and why Boeing thought they needed it on the newer variants. Keep your segments coming, they are definitely worth watching!

Thanks for the update, this has been an incredibly informative series of videos to watch as they always are, keep up the good work.

I can't express anymore thanks, than the other posters! You've got a Second Career ahead of you in Flight Training, and 'Real' Journalism!

Wow, Juan. I usually try to stick to relevant questions & let other heap praise on your well done reports. But I'm just blown away by this one. To say it's a lot of very good information in one posting would be a gross understatement.

I remember the T-37, a friend of mine called it the six thousand pound dog whistle because his dad's lab would howl every time one flew past.

Really Really Really great work. Even for those of us who arent in aviation and only watch Air Crash Investigations/ Mayday religiously. I get it. I think this is the best explanation out there. Ps i was one of those who refered to the jackscrew and Alaska Air incident. I think we got what you meant about the trim.. its just we didnt get how the system fully pushed the nosedown and why pilots couldnt recover - which you explained soooo well here. I think for me, personally, that particular episode of Alaska Air, i felt, was the most traumatic, just the overwhelming helplessness of the pilots fighting and trying to save the plane... it was too sad. So my mind automatically went there when you said the word jacksrew - ofcouse knowing it wasnt the reason of the loss of flight of the Maxs. I hope that helps. Your series on explaining the Max was great :)) Thanks

Excellent explanation. Also, thank you for your service to our country. Like we we told in training, most air saftey regs were written in blood. From an old Navy aircraft mechanic.

My wife was very concerned about the 737 Max. Thanks to you, I was able to explain to her, what the possible problems were and why we would not be flying on that aircraft next week. My father was a aircraft accident investigator, during WWII and he helped me realize that in most accidents there is rarely one simple cause. You reminded me that accidents are usually the result of series cascading events. Thank You Randy p s Luscombe fly-by-wire = LoL

Your videos are great. Perfectly clear. Keep em coming! Hell of a resume.