Runaway Stabilizer!! How to stop MCAS.

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If MCAS would activate on The Boeing 737MAX, what is the procedure that the pilots are supposed to use to stop it?
There has been a lot of speculation and information in media during the last couple of weeks regarding the new anti-stall system installed on the new Boeing 737MAX. The fact is thought that the procedure required to disengage this system, as well as ANY other unwanted movement of the horizontal stabiliser, is covered in a checklist called "runaway stabiliser". What that checklist does and how it works is what I will explain and show you today.
After the video I would love to discuss your thoughts and questions inside the Mentour Aviation App chat! If you haven't got the app yet, use the FREE links below! 👇🏻
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A huge thank you to all channels that were featured in todays episode. To see the whole, awesome videos, use the links below!
Topfelya (Awesome 737MAX takeoff)
• Boeing 737 MAX takes o...
Anders Cornelius Olesen (B737 Jackscrew operation)
• Boeing 737NG horizonta...
Inside Edition (Ethiopian B737MAX crash simulation)
• Flight Simulator Recre...
TheYottaTube (Elevator check)
• China Southern Cargo -...
Icarus Windjammer (Stabiliser closeup)
• Retired WFU and Answer...

[@bnr32rbpower]

I wish everyone following the news about the 737 MAX could see this video. I am so glad that this is being explained in a way that anyone can understand. I did some research online following this accident and once the found the jackscrew of the accident aircraft, I knew it was most likely a stabilizer trim runaway instance. I am so tired of hearing the media talking about MCAS and not explaining the system in its entirety, as there are some very key elements to take away from that knowledge. I keep hearing people talk about it at work, yet they have no idea what they're talking about, they are just repeating what the media says (although I can't really blame them as that's their primary source of information). Not an airline pilot by any means, however I do hold a CPL with ME and I am constantly correcting my coworkers on inaccurate information they are giving out. Anyways Mentour, great video as always and your channel is great! I want to continue to learn from an experienced professional like yourself, and hope to get some key takeaways that I can apply in the real world. Oh, and the Mentour app is FANTASTIC!

[@MentourPilot]

Thank you! Great to hear that you liked it. See you in the app!

[@VWaudiRULEs]

But is a malfunctioning MCAS just a trim runaway? It doesn't fully fit the definition, and several crews did not recognize it as a trim runaway. Trim runaways, at least in the classic sense, have to be continuous. MCAS is intermittent, a lot stealthier, and is accompanied by unreliable airspeed and a false stick shaker. You have to consider the human factors here. In the end, it is a system that was not disclosed prior to the Lion Air crash, and it is actually a very poor design - relies on only two AoA vanes, and when one of those fails, the system can start following data from the faulty AoA vane (or ADIRU, wherever the problem is). No redundancy, no fault-proofing. Oh, and the AoA disagree light was an option sold separately.

[@MostlyPennyCat]

@@VWaudiRULEs It's that lack of a disagree light that's critical I think, that and failed documentation and training procedures. If there's a fault and you didn't buy the fault light on the instrument panel, or just the fact it wasn't standard equipment, that is a systemic flaw in the purchasing/certification procedures.

[@davidgrandall2783]

I have been dismayed by the utter lack of knowledge on the part of the media (at least in America) when it comes to anything technical. After the Lion Air crash I learned here that there is a stabilizer trim cutoff switch which would have stopped the incident dead in its tracks. I have not heard "stabilizer trim" mentioned from an American media outlet. Not once. Nor that "stabilizer trim runaway" is something the pilots practice and have "memory items" for. Yes, the software was definitely faulty. But why didn't the pilots realize the trim wheel was moving? It's a 737, how can the pilots not know the wheel is moving? As always, thank you for a comprehensive video!

[@europaeuropa3673]

The less the media knows.........................the more they think they know everything. It's not just true about the 737 Max, but everything else including politics, weather, health, medicine, energy............did I miss anything?

[@MartyBecker]

What I really like about your presentations are that they are not full of edits between sentences. Your communication skills are very professional.

[@stuartmcconnachie]

beckerm13 Agree, but watch for the outtakes at the end and you’ll see why! Never film with animals or children... 😉

[@cnordegren]

I have stated in a few of his videos that he is one of the best overall youtubers.

[@deeanna8448]

Yes, he explains things really well, like a teacher. I like how he pauses and says "ok?"

[@xxxxxGhostBoyxxxxx]

@@stuartmcconnachie wrong. i came here for Molly. I can watch her all day.

[@theRealDavidn]

And the dog is just a world beater

[@dmitrikonnov922]

I'm not a pilot but I have been interested in the aviation all my life. This channel is absolutely fantastic because made entirely by professional but without any smugness towards laymen. All the explanations are understandable. And the dog is really cute.

[@helenafranzen9828]

Not only are you really good at explaining things nerds and professional stuff at a layman level, I really like how respectful and nice you are to your trainees. Way to go Petter!

[@deccers3906]

"The quick reference handbook, that's a little manual we have..." *reaches down and pulls out a book the size of 6 dictionaries*

[@ericbedenbaugh7085]

That's why you memorize the most essential items.

[@HappyBeezerStudios]

About the size of half of an IBM PC/XT operations guide. And there are 8 of them

[@RoelandJansen]

you haven't seen the other manuals yet.... ;-)

[@Rufus_L]

"Little" is a relative term and compare to the other manuals it's quite little

Well that's not that big. Certainly not a dictionary.

[@CriticalThink]

Thank you so much for making this video. It's refreshing to listen to someone who actually knows what they are talking about. There are too many people with opinions that actually have no idea what they are talking about or are not qualified to talk on a subject. Your clear and concise explanation is fantastic.

[@pudgeboyardee32]

For reference that jack screw is of a similar type used in most heavy manufacturing applications. Industrial mills and lathes use them extensively and regularly. It's actually interesting to me to see them used here with an articulated yoke mechanism as most mills and lathes use something much simpler. Still, it was very nice to see technology I use being used to fly. Thank you for showcasing that. Also it's worth mentioning that the smoothness of movement is controlled by software that measures distance of travel along the screws in milliamps. That means that the jack screw could be adjusted by increments smaller than the thickness of a sheet of paper. This is why a jack screw setup provides such fine and smooth control: an analog input is translated to an amount of amps and then that number of amps determines the travel of the yoke on the screw at a constant speed. Very neat.

[@gorillaau]

I wonder if the same thread type is used in the jackscrew, which is Acme, as also used in mills and lathes. It's a square thread that will allow a lot of pressure before stripping off the threads.

[@HDAviationVideos]

Mentour Pilot, I don't watch Netflix, I watch your videos. Definitely one of the best channels for people into aviation! Great work, keep it up!

[@GregSr]

Excellent explanations - as usual. I'm not a pilot but I worked with pilots in a KC-135 flight simulator (US Air Force). The KC-135 is a Boeing 707 designed to carry up to 180,000 pounds of JP-4 jet fuel intended for air refueling. As a simulator tech, part of my job was to observe the behavior of the simulator whenever the pilots were flying a "mission". I did this for almost 4 years and I saw many examples of the right way and the wrong way to deal with emergencies. Many times the instructor pilot (from his control panel) would command the trim wheel to runaway and then he'd watch how the pilots deal with it. In some cases one of the pilots had to grab the spinning trim wheel with their bare hands to stop it from spinning. That wheel is turning with a fair amount of torque - so it can get rough on the hands.

[@giaccommander7474]

these videos made me realize what it means to be a captain... Seeing two person working together as one mind is very wonderful. Knowing that pilots all around the world achieving this gives me hope, that we might one day learn to pilot our planet in a safe way too. ;)

[@3Authoress]

Forgot to mention, the little talk bubble-texts you added by your adorable dog are cute and hilarious. Love it. Thank you again for all of the great videos.

[@orchidjewels48]

I love his dogs!

[@gorillaau]

@@orchidjewels48 I love it when the dogs become a secondary focus/distraction.

[@ronmoore5827]

Very informative as always. Nice to hear an explanation by someone with knowledge and experience. As a private pilot and former military aircraft mechanic, it makes me want to yell when the media starts talking about something they know nothing about! I think in the end Boeing, and the Airlines training are going to share the blame for these incidents, but let's wait for all the facts.

[@TheRealMarkS]

" . . . trim out the forces" was like a giant light bulb. I felt comfortable that I understood what was going on, but those were the best, easiest to understand four words by way of explanation. Wonderful video as always. I'd love to see the sequence of in-cockpit events if this occurred at 5,000 feet. Not being a pilot, I think *I'd* be inclined to skip directly to killing the trim stab switches, and start cranking. There's not much time to try/evaluate at that altitude.

[@ArthriticThumb]

Me too, between “trim out the forces” and “a rugby team all going to the toilet at the same time” 😂. What I don’t understand is, if it is that easy to cut off the MCAS. Why didn’t Ethiopian Air do it? Boeing must have put out a notice, right?

[@Underwatergoat1]

@@ArthriticThumb it's not clear. A documentary I watched suggested that Boeing deliberately covered up training/familiarisation needs in order to sell the aircraft. There are several films suggesting serious (criminal?) collusion between Boeing and the FAA. It's not clear to me. Remember that media tends to go for big headlines even if it distorts the truth. What does seem clear is that the pilots of the two crashed aircraft were unable to regain stabilator authority. Could it be that they were unaware of the jack screw motor isolation process? I think it's possible but not certain. In the stressful situation we can react in many ways.

[@sarthakmohanty997]

@@ArthriticThumb They did do it. But as far as I remember, the malfunction occurred close to the ground (lower altitude) which gave the crew insufficient time to recover from the upset that MCAS had put them in.

[@sarthakmohanty997]

@@Underwatergoat1 It is no secret that the very reason the 737 MAX variant that crashed existed majorly as a response to Airbus coming out with the A320neo which gave much better fuel economy due to the larger engines that they were able to fit under the wings. Also, fitting of the newer engines did not change the handling characteristics of the A320neo all that much from the original A320. This was desirable because airlines did not have to retrain their pilots for the A320neos which saved them lots of money in additional training costs. Boeing, at this point, either had to replicate what Airbus was able to achieve or risk losing market share to Airbus. Hence, the 737 MAX, the MCAS, the covering up of MCAS nomenclature from documentation to sell the aircraft and you know the rest. Another factor that very few seem to be talking about is the fact that the MCAS (a very powerful and safety-critical system) was taking data from only a single AOA sensor thereby creating a single point of failure. Automatic, safety-critical systems in the Airbus always take in data from multiple sensors to avoid creating a single point of failure in that if one of the sensors failed, there are other redundant, functioning sensors that can still supply accurate data to the autopilot so that it can continue doing its job. And, in a worst-case scenario, if more than one sensor fails simultaneously, the autopilot systems in the Airbus would relinquish a lot or even full control of the aircraft to the human pilots so that they can deal with it. This did not happen with MCAS which continued functioning despite a faulty AOA sensor.

[@bobbycvsixfour5258]

MENTOUR PILOT TEAM continue to advance your videos. Your comment about the recording being not as professional was actually MOST AWESOME. WOW, what happened in the cockpit was SUPER GREAT.

[@gregswartz8924]

Fantastic, clear discussion, as always! Sorry if I missed any previous comments to the subject, but your "navigation lights" pillows just jumped out at me on this vid. I went back and realized they have been there for a while. Living the life!! And yes, your dog is cute as all get-out. But we all know that. Fly safe!! (Ode to S.M.)

[@robhobsweden]

If nothing else works, make the rugby team run back and forward along the isle at your command... ;)

[@liamcarruthers2721]

Robert Lindhé 😂😂😂

[@rofo2107]

spot on

[@NipapornP]

We really had to do this one time on a long haul flight. The aircraft was only 1/2 full, and all PAX were ordered by the captain to the most back seats of the plane (A330 or DC10, I don't remember) just before takeoff. At about FL200 we were allowed to change back to our original seats.

[@SUPERMONJ]

😂😂😂😂😂😂

[@noahwilliams8918]

Now that’s Crew Resource Management!

[@LACTS-be7pr]

After watching this video I just received my KZbin Pilot license...Thanks, Mentour Pilot...Tschuuss.

[@johnFruetel]

Brilliant as always. Thank you for explaining this complex topic in layman's terms

[@buddyclem7328]

Nice sponsor transition!

[@Zelig2Cents]

That was a phenomenal video! Thank you! The flight sim practice with the runaway trim at the end was especially effective at demonstrating what you taught earlier in the video. On a parallel topic, for those that do (in-home) Flight Sim work, take a look at the new Yoke by Honeycomb Aeronautical. At $250, not only is it dramatically better with respect to resolution (realism), greater range of motion for aileron control, losing the center detent, etc, that cheaper yokes suffer from, but it also has the double-switch for electronic elevator trim that is used by actual aircraft. As far as I can recall, not even the $1000 Yoko nor the $1300+ Brunner Yokes have the double switch feature. The double switch is a safety design so that if one of the switches fails and continuously inputs elevator trim even after you release pressure on it, so long as only one switch has that problem, the trim will not change. BOTH switches have to be moved forward or backward in order to input control to that trim. The likelihood that both switches will have that problem is extremely low. Austin Meyer, creator of X-Plane, was so impressed with Honeycomb's commitment to that hardware addition, that he added that programming to X-Plane to accommodate the double-switch electronic elevator trim. I hope Honeycomb succeeds in a huge way. The founder has promised that once they're up and running with their yoke and throttle quadrant, they will be introducing a yoke - sub $500 - with force feedback!! Hope some of you find this info helpful and that I didn't stray too far from the topic of this video.

[@SpamMouse]

That Patxi allows you so much freedom to chat when he is busy relaxing shows how tolerant he is. A question whose answer might depend on airline policy, when you are flying with another pilot for whom either their native language is also Swedish or speak Swedish at a proficient level would you still carry out check-lists and flight procedures in English or Swedish? But maybe switch back to Swedish to discuss a stop-over story or mid-flight gossip?

[@gordonrichardson2972]

Spam Mouse Always English in the cockpit, its 'work' not chat.

[@yoidoretennshi777]

This is the best video I've ever seen and explains so well about the questioned issue that even an amateur like me can understand the whole mecchanism and the check points in order to avoid the critical problemes caused by malfunctions of trim systems. Highly recommended

[@sushimamba4281]

If only all pilots kept their knowledge as thorough and up to date as you. Great stuff.

[@richardrodrigues783]

Sushi Mamba That should be required for recertification of pilot's licence every two years.Refresher course in flying with flying in simulator with instructor. And actual flying with instructor.

[@TheJoshRed]

I'll be sharing this video with all the friends and family asking me about this accident. I'm a Boeing mechanic here in Seattle with no answer to who's to blame. This video shines a bright light on actual FACTS. Thank you Mentour Pilot for sharing this video with us!

[@johnallen4793]

🤣 🤣 🤣 The subtle side "comments" from his dog is a great addition 👀🤔🤣🤣🤣😍

[@kingstonsean]

I saw a comment online this week that said the memory check list only applies to "continuous" stabilizer runaway and therefore is misleading in case of "repeated uncommanded runaway stabilizer" condition! I basically just shook my head and moved on. But if I can find it again I will direct him to this video.

[@Phaidrus]

Some weight lifting sessions at the gym are definitely helpful in order to control those nasty runaway stabs! Peter turned those wheels like a boss!

[@andis9076]

He is turning with the right hand.

[@gordonlawrence4749]

With regard to the manual physical stop of the trim rotors, there is a very important point with regard to physical strength that applies. Humans still have some of the physical adaptions for basically swinging from branches. This means static pull strength for most adults will vastly exceed static push strength. When I was younger I rowed at national level. I could put 800+ pounds of pressure through the oars. That's 400+ per hand. The flip side of that is I think I peaked at something fairly weedy like 190 pounds for bench press. That is only 95 pounds per arm (I could actually bench pull more than that). Not only that but as Mentor Pilot said the risk of wrist damage is vastly reduced on a pull compared to a push.

[@ryankennedy3109]

Agreed. It seems the pilot could apply the most force by pulling and simultaneously bracing with the legs (in other words, a deadlift-like motion).

[@stephen_101]

Really appreciate your efforts in bringing us these videos and concise information - thanks man!

[@wendygibson2800]

Captain! Me one of your biggest fans since I found your videos about one year ago. It was truly great to see you actually 'behind the wheel' so to speak! Big thanks from me Wendy, for all you videos. I am looking how I can support your work. Just a bit difficult from South Africa. I listen to your videos such a lot.

[@kristinefrink5726]

Thank you, Mentour Pilot, for your series of comprehensive and layman-friendly productions. I also apprreciate the input/short videos of your sweet pups! One can usually trust dog lovers as dogs know whom to trust! Yay for the darling new additions to the family (and congrats to the parents, though of course, all the credit should go to the MOM!!)

[@EveryTipeOfVideo]

Petter grown some muscles holding that yoke 💪

[@lokon1979]

EveryTypeOfVideo Haha his argument could easily be that’s not his dominant arm

[@strippins]

These videos are extraordinary - no other channel gives such insight and explanation into how these planes work. Immersive and fascinating.

[@xm1193]

Trim wheels are no match for Mentor Pilot! “Let me help you” (colleague’s arm almost flies off). I would feel very safe being a passenger on any flight with Mentor Pilot at the controls. Thank you for making this video. Hopefully the media will stop being so hysterical.

[@mytech6779]

This.

[@movinbutnotshakin]

That jackscrew is a beast to turn but glad pilots can tag team it. Also, thanks for the excellent, professional explanations. After reading news articles from nontechnical journalists, this video cuts through the noise and clarifies everything.

[@rafaelcastillo466]

Magandang Umago Po! I am Flying from the Phillipines To LAX via Taipei, China Air. I Believe a 777-300 ER. I have always been uncomfortable flying. Your Professionalism And Attention To detail gives me a new perspective on the flight crew operation. Thank You Maraming Salamat

[@richs6205]

Always informative, factual, and positive. Appreciate the information on this sensitive topic.

[@hartfischer5509]

Half the people watching, are here to see the cute doggy roll around on the sofa :) The other half is glued to the great in-detail information about airliner technology. Love your channel :)

[@jpe1]

Dog perks up ears at the word “MCAS” 😄

[@MentourPilot]

Yep!

[@czdaniel1]

Dog is jealous of all the attention MCAS is getting.

[@czdaniel1]

Also, MCAS = Worst dog name ever!!!

[@cnordegren]

Puppy knows!

[@GeneralPurposeVehicl]

@@MentourPilotIs that the floof's name?

[@unvolador1]

Thanks for the video. One HUGE difference between the NG you are in and the MAX is that the NG has a trim brake which the pilot activates by moving the yoke in the opposite direction of the runaway trim motion. You can see this in your video as the trim runaway is trimming nose down and you pull back on the yolk, the trim stops. The MAX MCAS does not allow trim brake activation by pulling up on the yoke. When MCAS activates the only way to stop the trim from trimming nose down is to trim nose up with the yoke trim switches or shut off the main electric and autopilot stab trim pedestal switches. The trim brake is also why the first officer had trouble moving the trim wheel initially in your video. You were pulling back on the yoke against the aerodynamic forces and the trim brake was engaged. Trim brake actuation in an NG makes it hard to simulate the MCAS activation the MAX. When MCAS goes off in the MAX the nose down forces progress quickly with no stopping from a trim brake system. All that having been said, your video is a great educational tool. Thank you for taking the time to post it. Maybe you can post another video explaining the differences between the NG and the MAX. I am a Captain on the 73 for a major US air carrier with 18 years and over 12,000 hours of experience on the 73. I have flown the -300, -500, and now fly the -700, -800, -900, -900ER, and -9MAX.

[@gordonrichardson2972]

Kevin Douglass Very useful feedback! One disagreement, the B737 NG does not have a trim brake, but a yoke activated underfloor trim cutoff switch. This switch has indeed been removed on the MAX, which adds to the complexity and confusion.

[@unvolador1]

Thanks for the clarification.

[@sespach]

Your explanation is far better than any described in the media in the USA. Yours allows us to be able to understand what might have happened with the higher and more forward mounted engines on the 737 max. thanks for your calm delivery. As a cardiac surgeon friend of mine once told me “Always walk into the room!” This shows the team that your confidence and controlled response to a severe situation rather hurried and frantic response.

[@jameslovell8682]

I wasn't even aware until this last week, that the entire horizontal stabiliser could move, as I thought it was only the elevator that moved. Likewise the trim wheels. You learn a lot from a tragedy. (Let us hope that Boeing/FAA learns too)

[@mytech6779]

Moving the whole airfoil to trim makes a better lift to drag ratio as compared to only moving the elevator, but it is mechanically/structurally more complex; and it provides more total adjustment as the CG of a long body aircraft could vary substantially. Small aircraft, as he mentioned, only have a little trim tab on the elevator along with a more aerodynamically balanced elevator shape; in this case the goal is only to relieve yoke pressure during different phases of flight while the loaded CG should only change a small amount.

[@kg-Whatthehelliseventhat]

So the wings create lift to go up and the horizontal stabiliser pushes down?

[@danepatterson8107]

Outstanding technical description of how pilot trim setting functions! I'm not a pilot, but I get it now (didn't realize it was that simple to set from the yoke)

[@leanneelizabeth3546]

This video was absolutely excellent! I loved everything! Patxi's captions, the explanation AND the demonstration. Well done! Your professionalism is outstanding and always motivates me to do better! :)

[@TheWahyuwirawan]

even me as a non-pilot people can understand your explanation so good.. boeing should take you as one of the lecturer of their new planes or systems or emergency checklists and saves more lives

[@Dobermanator]

I know little to nothing about aircraft piloting. I am found of World War 2 Aircraft and an overall appreciation for all aspects of flight. Having said that I believe I might be missing out on something significant if I were not subscribed to this Channel. Well done, very well indeed.

[@mattcwatkins]

This video was timely and HUGELY helpful to me in understanding technical details about 737s certainly, but also some things I had been wondering about as the MAX questions are swirling. Walking through the SPECIFIC details and process for runaway stabilizer was huge for me. The two switches to disengage was a revelation to me. And if that weren't enough...the description of what one does with those whirling wheels of metal with little levers cemented it even more. Throw in the observation that it's 'possible', but a big PITA to even do without the levers affirmed my perception that would suck. Finally, put up simulator video of that process and I going to magic a prediction that I'm going to have a far better understanding of the MAX issue when the finish their full analysis. Thanks sir! I think I'm an even bigger Boeing 7x7 fan now.

[@sparkplug1018]

The one thing he was very careful about not speculating on was that its likely the pilots didn't recognize the problem for what it was quickly enough. This is after all a very rare failure to occur. But beyond that, failures of any kind are pretty rare in modern aircraft they're designed very safely. The only real questions to answer in this are, did the pilots recognize the failure for what it was and why does the MCAS rely on only a single input to make decisions.

[@tsuchan]

Thanks Mentour Pilot. That was a really valuable video... you're doing fantastic work in teaching us.

[@nunya3797]

Co pilot needs some gym time on left arm.

[@henryherlangga1159]

Yeah... He looks weak...

[@cyrilldaepp4082]

Or cheat on his right hand and start an affair with his left hand...

[@billl605]

gigity @@cyrilldaepp4082

[@maribmw525]

Totally agree. If you had an FO with only 200 hours and a weak left arm or shitting his pants in panic, then all is surely doomed.

[@olelaustsen8657]

😂😂😂

[@TheLocoUnion]

Thanks!

[@MentourPilot]

Thank you so much for your wonderful support!!

[@Slyze33]

Don't beat yourself up with the quality of the simulator video, it's already quite illuminating. As far as I remember you're one of the only one out there doing these kind of simulator videos. Would you like the medias to show this part to inform the public if it were to happen? :-)

[@shakti.rathore]

The doggy dialogue part was cute :)

[@sarlineh]

Your best and most interesting video to date, IMO. Really appreciate the great content!! Thank you.

[@rennison1211]

Thank you for the time imparting your knowledge sir! Never a stone left unturned! Very articulate, simplified and clear.

[@xcalibur3]

Excellent video, and very germane to the whole MAX 8 MCAS clusterfuffle. Actual pilots would benefit from watching this video (I know, I know, it's not official training material, but still!). Boeing execs take note - this guy knows what's up.

[@rolandalfonso6954]

There used to be a saying that flying an airliner is ninety percent boredom and ten percent terror. If true, this certainly proves it. I was frightened. I'm a little old guy but I believe that adrenaline would be released in mega doses and I would crank that trim like there's no tomorrow; because there could be no tomorrow...great video.

[@gregsiska8599]

Mentour, you have done a wonderful job getting this information out. Thank-you!

[@vonnikon]

From what I understand, the MCAS runs the trim for 9 seconds, pauses 5 seconds, then trims agsin. And so on. That sounds like a whole lot more runaway trim applied much faster than in this simulator session. Also, at a lower altitude and with much higher airspeed. With the reaction times demonstrated here, would you have been able to recover? Would you have sufficient physical strength to trim manually when it is even more out-of-trim, at higher speed and lower altitude? Lots of forces on that stabilizer. (The Ethiopian situation)

[@Crunch_dGH]

@Mentour Pilot ???

[@Fubo777]

Also, aren't these MCAS events accompanied with stick shakers and aural STALL warnings too (which doesn't happen in normal runaway stabilizer events right?), so the poor pilots must have been confused shitless, and taken even longer to realize what's going on. @ Mentour Pilot

[@RaterisimoCBA]

I have the same question .. seems like Ethiopian MCAS trim action was fierce and relentless .. if pilots had disengaged MCAS completely before the last hard nose dive would they have been able to recover control ? (I dont Even know if they managed to disengage MCAS at all) ..

[@deniseharden958]

@@RaterisimoCBA also it is my understanding that the Ethiopian pilots had memorized the procedure boeing said would allow you to recover. You can hear them on the cvr troubleshooting the problem. With in 30 seconds one pilot identified the issue and the other pilot confirmed. They begin executing the recovery checklist from memory doing it more than once and started pulling together together. You can hear the captain saying"pull with me" it didn't save them.

[@TremereTT]

@@RaterisimoCBA The Ethiopian 303 flight had their engines at 94% throttle the whole time...(the fligh recorder data is now published) IF manual trimming and steering requires more muscle with higher speeds , that's a bad thing. So if the pilots were surprised by the MCAS and forgot to shut of the autothrottle this might explain the full throttle engines. Now why would the autothrottle keep firing the engines full power during a stall? Boings autothrottle has a low altitude level off capture mechanic, that might be responsible for that. So MCAS problems and the low altitude level off capture of the autothrottle might be a deadly combination. I'm not a pilot. I'm interested at the MCAS and autothrottle-low-altitude-level-off-capture bug as a software engineer, especially the Human-Compunter-Interface perspective is very interesting for me. currently my opinion of the MCAS system is that it's a cheap trick to avoid pilots needing to get certified to a new type rating. It looks like there is no training for the case of MCAS failing, obviously because 737 max is just the same "type" of plane as a 737 ng...dispite the 737 max actually having different systems... And then this MCAS is one of this systems that has no redundancy. One Sensor could trick it into behaving not as intended. The whole design asks for problems. I think dealing with two automatic systems behaving wrong -autothrottle-low-altitude-level-off-capture -MCAS fail was to much for the pilots to process at the same time. I think they basically only focussed on the MCAS and ignored autothrottle-low-altitude-level-off-capture. There is only so much you can demand from a human operating an interface. There is a maximum of information a human can process at the same time. I wished Boing would change it's philosophy and make less but more important information more prominent available to the pilot.

[@anonymxs._7570]

You are wearing long sleeves. Looks good. Incredible video! I love it, keep it up man!

[@MentourPilot]

Thank you! Glad you liked it!

[@joelzimmerman2462]

Beautifully explained for an aerodynamically complex subject (a variable angle stabilizer increases the authority of the elevator over a wider speed range than a fixed stabilizer, hence a jackscrew adjustable horizontal stabilizer. On larger aircraft, we use double redundancy hydraulic motors to actuate the stabilizer jackscrew, but the procedures are the same, per the QRH, disable, identify the malfunctioning system, re-establish the operative system (or not, on a bad day! ) and land at the nearest suitable airport .

[@superboykiller1969]

Thanks💪

[@FirstnameLastname77777]

Loving your full sleeve uniform as always keep up the amazing videos coming

[@trainsplanes6517]

Great presentation. I wonder if the MCAS malfunction might be more insidious than a straight runaway trim and by the time it's recognized the trim might be beyond manual elevator authority. When you encountered the problem in your sim flight, you were ready for it. But years from now it could sneak up and bite somebody again if they don't react immediately and positively. Also, If my understanding of MCAS is correct, it should never operate in normal flight. So shouldn't Boeing install a audible/visual warning light whenever MCAS inputs trim? Thanks!

[@johnFruetel]

I'm impressed that the 737 still has has good old fashioned mechanical cables to trim the aircraft if the automatic stuff doesn't work right. No computer will ever outdo a human pilot doing everything they can to get the airplane flying right

[@RobertSzasz]

In the most extreme edge cases, sure. The worst problems come when automation works almost all the time, but design choices mean the pilots need to both identify and correct failures. The mcas system should have been designed to Not activate if there was a sensor discrepancy, or fully integrated into the fly by wire system and just been one part of the control system. (New software changes seem to do some of the latter)

[@andrewhull3808]

Yep, in the words of an old Yachty when talking of the lack of bilge pump on his small racing yacht... "In my experience, there is nothing that pumps water as fast as a frightened sailor with a bucket!" Manual back-ups are always preferable because computers do not understand context.

[@tunespt]

Months of training in one small video, even for people who love aviation and has some little understanding how this wonderful machines work. Thanks. Really got finally how trim really works. You can make more videos on how to deal with less common flight issues and so on.

[@GokuPlaysUK]

I like how you can explain this with ease but other professional pilots did not know how to respond to the recently fatal accidents .

[@Jon_Godfrey]

Great video... I’m not a pilot but I can imagine that would be quite stressful especially at low altitude and with addition of stall warning and stick shaker. Of course you avoided that with fast actions but the time window does allow much for confusion or hesitation.

[@elroynathanael6535]

Yes that's why proper training is absolutely mandatory

[@pilot_ricky]

I'd just fly inverted in case of runaway stabilazer failure! (Denzel Washington)

[@ABissoon-u4e]

😂😂😂😂

[@SeanBZA]

Only for 20 or so seconds before the engine cut out from lack of fuel. Pick ups are in the lowest part of the tank, and you do not have the inverted flight tank, that fighter aircraft have, that allows inverted flight.

[@souocara38able]

That has been done. Passenger plane flew inverted for quite a while because that's the only way they could maintain any control. Unfortunately when they tried to land it didn't work out very well :-(

[@brillwatuma4973]

You would definitely save more lives.

[@pilot_ricky]

@@brillwatuma4973 ahaha LOL😂😂

[@alant5757]

I was right about the jackscrew and finally I got to see it in action. And thanks for the simulator video. I am just a guy who loves aviation and find it very interesting

[@markfosseth8047]

These kind of videos made by a real pilot are pure diamonds, thx a lot !

[@spikedart]

This was perhaps for me, the most informative video you have done so far. Now I understand the auto-trim and how to work around it. Thanks for your excellent presentations.

[@TheCracker94]

Thank you for being so informative and responsible with your explanations! Great content, very clear and easy to understand!! thank you Mentour!!

[@andyrichardsvideovlogs8835]

That makes it much clearer. Thanks.

[@antonback3923]

Mentour I just want to say that youre videos are great. They really make my day. Föresten är jag svensk. :).

[@MentourPilot]

Thank you my friend! Trevlig helg!

[@antonback3923]

Man tackar!

[@antonback3923]

Ha en trevlig helg du också.

[@devikakarmakar99]

Thanks mentor I have just started flying a 737 max and Ng after 25 years of flying the Airbus series find you channel very helpful.

[@bobthompson4319]

I love when you work with someone you have never worked with before and you both are so professional that it looks as if you've been working together for a long time.

[@alexandermyrthue1987]

Mentour: You are a GREAT teacherr!!!!!!!

[@FrancoContreras]

haha First Officer looks that almost forget the memory items 17:50. Thanks for this video !

[@Marco-wz3ff]

i dont think he is a FO just yet

[@FrancoContreras]

Yea, still do better job than me haha

[@MartyBecker]

And he needs to work on some arm strength.

[@VincentRiquer]

Well, imagine if someone was filming you while you're taking driving lessons... Uncomfortable, right? [Edit: typo]

[@Marco-wz3ff]

@@VincentRiquer he probably agreed to the filming...

[@lahockeyboy]

You're videos are always interesting and informative...I wish Mentour Airlines operated in North America!

[@orionswatchers9775]

You sir are a national treasure and must be protected at all costs. Thanks for the videos, your explanations are so clear and I actually understand now.

[@paulrenny8388]

I noticed in your video that the Control Column Automatic Cutoffs were doing their job. When you pulled back on the column, opposing the runaway, the trim was automatically cutoff even before you manually activated the cutouts. The stab trim reactivated when you released back pressure. It is worth mentioning that MCAS works outside of this regime. The Control Column Automatic Cutoff switches would not have been effective in an actual MCAS event and the nose down trim would have been far more aggressive as a result. I did this same scenario in the Max sim a few weeks ago and in order to get more aggressive with the manual trim, I had to offload the elevator and reduce thrust to alleviate the aerodynamic pressure acting on the leading edge of the stab. If the AT was disconnected during climb thrust and not reduced, then the aircraft would accelerate. With high airspeed and back pressure loading on the elevator, the manual trim would be effectively seized. It makes me wonder if this is what the Ethiopian crew experienced and why they reactivated the trim.

[@MaltaMcMurchy]

Thank you for this very informative video and the bonus footage at the end! 🐕💜

[@randylinn502]

Love the red and green navigational lights.. oh I mean pillows..

[@ablebaker99]

yes - that's the first thing I noticed. He needs to get the dog to jump up and down behind him to represent the strobe light.

[@manasareddy3640]

Irony is that pilots didn’t know about MCAS a couple of weeks ago and now the whole world knows.

[@genevieve571]

Pilots have known about MCAS since the Lion Air crash. A good portion of the world too. With the second crash however, now everyone knows. Problem is, not everyone understands.

[@spankybear]

The reality is any pilot of the 737 (100-900 and the MAX -8 and -9) should have known the stab trim runaway procedure and it should be a memory item. Also every pilot of the 737 MAX should have been aware of the MCAS after Lion Air incident. This is all very unfortunate and sad.

[@rockets4kids]

How could pilots not know about MCAS after the Lion Air crash?

[@sector7offshore]

Boeing published the MCAS update February 1st so if the run away trim training didn't stick a previous crash and manual update should have made it clear

[@mountainconstructions]

@rockets4kids They most likely did know, but when the alarms send you down another path and you have 4 minutes to work through them, well.... thats different

[@Knitsewrella]

That cockpit demonstration of the trim wheel being moved manually was very helpful. Thank you!

[@jeffr985]

Who could dislike this video? Great information presented in a very professional manner but at a level understandable to the layman.

[@moow950]

Great video again with clear explanations 👍 Love your dog 🐶

[@andis9076]

Manual trim need muscle (18:44)! If the plane is diving down, alarm blinking, screaming, G-Force kick in, panic set in, this will even harder.

[@0xstuff625]

Adrenaline might actually make it a little bit easier!

[@sector7offshore]

So you're saying pilots are panicy people. Especially when they have Sim training to recognize what's happening and the memory point tell them to shut it off. .. and they're memory points so the pilot shouldn't be surprised by the occurrence

[@wernerdanler2742]

@@sector7offshore I understand there was no sim training required to save airlines money.

[@Robbedem]

And in the simulation they were very quick to find the problem. In a real situation their are probably a bunch of alarms blinking and sounding (autopilot doesn't want to engage, stall warning,...) , it might take a minute longer and that minute would increase the forces a lot more.

[@wildwest1832]

Yes, but I think mentour and many experienced pilots would know what to do. They also are used to these kinds of situations and know to not panic

[@johnks4002]

Great explanation. Nice port and starboard pillows as well

[@jamesbulldogmiller]

John KS I noticed that , too. I was looking through the comments for someone else that mentioned that.

[@ChuckKarl525]

Your explanation of this issue is to the point and no hidden agenda. Thank you for your professionalism. The news media could take some lessons from you.

[@johnbolin7098]

Outstanding explanation of the horizontal stabilizer and trim system and recovery procedures. It's hard to believe that the MAX pilots involved in the ill fated fights were not trained in these procedures.

[@sparkplug1018]

They would have had this training as well for their 737NG type ratings. It seems they didn't recognize the problem for what it was quickly enough.

[@sparkplug1018]

Doge Bomber That’s pretty much what I said, unfortunately in these cases the pilots didn’t recognize it for what it was and there’s the result.

[@MRBROWSER2012]

Great video and explanation again! Was interesting how hard it was for the FO to crank the hstab by himself. Let's see, you can turn off autopilot and auto-throttle but not MCAS without killing hstab power? That sounds like a flaw in the design. MCAS authority should probably have its own kill switch. Wonder if Boeing will add it now that everyone knows about it.

[@wesleyhurd3574]

Boeing was extremely quiet about the very EXISTENCE of MCAS before the Lion Air crash. At that point they were forced to tell pilots that the MAX had a new system which affects stabilizer trim. However, adding something as simple as a new cutoff switch could require pilots to have a new type rating which would cost money for the airlines. Now, after the Ethiopian crash, things are likely to change.

[@wesleyhurd3574]

@Sto So As John Baxter stated, the only method that the pilots would have known was to cut off power to the electric trim motors that change the angle of the horizontal stabilizer. I think this is the procedure that was mentioned in the video. This would disable MCAS but it would also prevent the pilots from being able to control the trim electrically with the buttons on the control yoke. The trim has to be manually adjusted with the hand crank at that point.

[@andreasplattner]

Dog Cameo is priceless 😜 keep up the dog's thoughts!

[@kurt9395]

It's so refreshing to hear someone discuss this subject who actually knows what they're talking about. Thank you! From what I read on the issue, MCAS was used in the MAX to give it the same flight characteristics as the NG and to safeguard against overthrusting the larger engines. Can you confirm this?

[@sector7offshore]

As stated many times MCAS was there to prevent the more powerful engines placing the aircraft in a stalled attitude. So it auto trims the pitch up caused by a higher throttle setting. Go back to his earlier video he's explained this as does pretty much every report on the max since the accidents

[@eagleviewhd]

Another very informative video. I only flew for two years back in the early 1970’s (lost sight in my left eye and quit flying - no depth perception). I flew Cessna 150 and Piper Cherokee 140’s. Despite having flown very rudimentary and basic airplanes, your information is easily understood. It seems that as long as someone takes the appropriate action in a timely manner, that there is no reason for ending up in an unrecoverable dive. Those memory steps are not complicated and should be foremost in the mind of the pilot. I remember the emergency steps we memorized if we suddenly lost power in our little single engine Cessna even after all these years of not flying.

[@edwardessa3369]

I have a great admiration for you as a pilot, aviation educator and ,very importantly, an avid animal lover, as evidenced by your very natural and comfortable simultaneous integration of your dog as you proceed through discussion. Thank you !

[@washlines]

Very interresting to actually get view of the runaway trim scenario. Cudos on the explanation. Still one question, after finally successfully getting the trim to stop adjusting itself, both autotrust and autopilot were switched off in the process You ask the first officer to give you 220 knots and he adjusts the auto pliot’s speed input. That should do nothing now, should it, or am I missing something?

[@Interdimensional27]

I was wondering the same thing...

[@RazvanMaioru]

Setting it there also helps by putting the pink speed bug at 220 knots, which makes an easier visual reference than reading the numbers on the screen for manual adjustments

[@1232bluejays]

There's a theory that Ethiopian pilots went right to stabilizer cut off immediately before trying the electronic trim. Then airspeed was such that manual trim was too difficult so they turned the stabilizer cut off switch back on which re engaged MCAS which then continued to push nose down

[@MissCase530]

That isn't a theory. They can hear the electric trim motors right before the last nose down sequence from MCAS. Unfortunately it is documented that in the severe outof trim state they were in, the electric trim doesn't work, you have to fix it manually. They were already doomed at that point.

[@falconeaterf15]

The Ethiopians knew they had an MCAS failure almost immediately thanks to lessons learned from Lion Air crash. They followed the procedures Boeing issued to safely resolve the condition, but crashed anyways when they could not trim the aircraft using the mechanical trim wheel at 350 knots. Pilots in a simulator had the same result at just 250 knots of airspeed, but saved the simulated aircraft by roller coasting as they worked the trim wheel. This used up over 8000 feet of altitude, the Ethiopians never got above 6000. When they knew they were doomed, they switched MCAS back on seconds before impact - hoping for a miracle that sadly did not happen.

[@ericbedenbaugh7085]

They never disabled the auto-throttles, despite almost a minute of overspeed warnings. They were simply going to fast to manually trim the plane.

[@Ranger-vv2jv]

Appears the 2 crashes could have been eliminated if the Pilots had this training.I am a mechanical engineer. Training should be essential by whomever are responsible. Excellent Sir

[@sector7offshore]

They did have the training this wasn't an Mcas demo this was a run away stab trim and how to deal with it which clearly it is recoverable and is documented

[@aps-pictures9335]

What you are missing is the speed of a real major failure. As he said in another vid - if you don’t reach the last memory item in time - and the stabiliser has rapidly reached its most banked position... there’s NOTHING that can be done to counteract it in time. Especially at low altitudes.

[@46lfries]

Mike go to the blancolirio Channel Juan Brown flies 777 he gives the best explanation this guy is sharp sharp sharp he's flew 141 star lifters C-130 737 and a whole bunch of other airplanes been flying for 40 years update 20 March scroll through you'll find it

[@46lfries]

@@Passions they didn't have time to go through a check list they should have been on the simulator yes there's a problem with the mcas a day before the guy in the jump seat turned it off the trim the aircraft and flew home apparently nobody got the message the smaller Airlines have to use simulator in Europe the USA time on the simulator is piss-poor lack of training cause them to buy the farm what's all them people apparently those Airlines didn't want to spend the money they are now

[@46lfries]

@@aps-pictures9335 you ars correct see jaun brown 20 March blancolirio channel KZbin he's got the best explanation

[@nzcyclone]

Another awesome video as always. Thank you. Yes, the first officer was struggling with the wheel. But, in saying that I would imagine there is also an awful lot of forces and pressure being exerted on it, just imagine the pressure that would be on it without the Jack Screw, more than likely would snap the cables possibly. Afterall with switches off there is no power assistance. Hehe loved the bit at the end with the dog. You should know by now this isnt your channel anymore it is the dogs.

[@mrlax5304]

Trim wheel when mentour starts trimming along with the FO: I’M SPEEEEDD