Boeing 737 Stall Escape manoeuvre, why MAX needs MCAS!!
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- Опубліковано 21 вер 2024
- 2 FREE months of Skillshare! skl.sh/mentour...
Why does the Boeing 737MAX 8 need MCAS in the first place?
I am guessing that you guys have heard the word "MCAS" and "Jackscrew" being thrown around in Media the last few days but what do they actually mean? In this video I will teach you all you need to know in order to execute an "Approach to Stall and Escape" manoeuvre. I will explain why we do the things we do and WHY the Boeing 737NG is Different to the Boeing 737MAX in this regard.
As always, if you have any questions I would like you to write them in the comments OR, if you want to reach me directly, then just tag @mentour in the Mentour Aviation app-chat.
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A huge thank you to the channels that were featured in todays video. Please use the links below to see the whole videos!
Adam Penner (Airflow over wing during stall)
• Airflow during a stall.
TheYottaTube (Elevator movement)
• China Southern Cargo -...
S Riccardo (Stabiliser movement)
• A320 Trimmable Horizon...
Very interesting!. Learned more from you then any news outlet. THANK YOU
Excellent, that what I was hoping for
Emmanuel t's a sad fact of life that if you look at any main stream media article that relates to a subject of which you have knowledge the article will be sadly lacking in understanding. So even without political bias one is left to wonder about the validity of most news.
Mentour. I'm thinking throttle, throttle, throttle, throttle then you explain why throttle isn't to be instantly applied. Thank you as always.
My son is a pilot for AA. That is exactly how he explained it to me yesterday.
@@pilotboy3328 So these crashes might have happened because the pilots added throttle to bring the nose up but it went down so they added more, a few cycles and then crashed?
Great video. Did not learn why MAX needs MCAS. Suspect my RCAF Pilot father, RIP, would not understand either.
You can see just how uncomfortable both pilots felt with the "airspeed" verbal warning, even though it was only a simulator. He wasn't kidding, that warning definitely wakes him up.
You're kind of cute, Olivia Lambert. Hi from DC.
@@diplomacy2000 creep
@@alioli1998 good song
Nah, I didn't see that. But, it would wake you up, no doubt.
Also, yeah pretty creep.
Also, yeah good song!
@@alioli1998 and why is he a creep? For putting his shot out there. This is how people meet. Highly doubt you’d be saying the same thing had he been a she flirting with a man.
"i know i've made some very poor decisions recently, but i can give you my complete assurance that my work will be back to normal... i've still got the greatest enthusiasm and confidence in the mission, and i want to help you."
HAL - 2001 a space odyssey
Meanwhile Dave is pulling holo memory cores from the mainframe.
@@ph11p3540 " Daisy, Daisy, give me your answer too..."
A fictional film so, yeah
@@christopherwilson6527 What....?? You mean that it was just a Hollywood movie and not real...??? I can't believe it....surely not..!!
No. Just ... just ... no.
“You’ll get ‘BUFFET ALERT’. Now this warning has nothing to do with food.”
Total deadpan delivery. I see you Mentour! Hahaha
Looks like doggo was experiencing some uncommanded roll!
Mentour Pilot - The place for accurate, unbiased aviation knowledge. Thank you.
He is pro Boeing , not unbiased.
and don't forget the amazing puppy
@@gledatelj1979
That doesn't make sense. What else is he going to talk about if he is certified on that aircraft and his company only flies these aircraft. And he does it very well and objectively.
Also, there is no argument between Boeing and other major manufacturers technology-wise. Flying in all of these aircraft models is amazingly safe nowadays.
Not always.
Vlado S lol
I am retired Boeing and have worked on the 737 project almost twenty years. You have explained the system and characteristics better that than anyone could.
lol "buffet alert has nothing to do with food"
I'm afraid the stick shaker isn't as fun as it sounds either..
when somebody licked the spoon and put it back into the salad
ATTENTION BBQ IS HERE
Actually the fuel kgs indicator is how much ORANGE JUICE is in both wings and the central fuselage tank, for this oragne juice-aholic (no, No actual alcohol!) This is my 'staple' my brain fuel! (Got any more OJ back there, Jim?)
Really great video! I'm not a pilot, just a big time aviation enthusiast. You explain everything so clearly that even a non pilot like me can understand. Thank you so much!
Was thinking the exact same thing myself
Peter is simply one of the best youtubers.
OMG, I was going to type the same thing, Thank You!!!!!!! OUTSTANDING Video !!!!!!!!
Simon Chase what is wrong?
@@simonblunden2151 Nothing at all. He explained all procedures accurately. That guy is either a troll or an idiot. Or both.
From the Seattle Times, “The newspaper said the analysis also failed to account for how the system could reset itself each time a pilot responded -- in essence, gradually ratcheting the horizontal stabilizer into a dive position.”
Yes just cranking more and more Hstab trim is not a good plan.
Frightening to imagine control inputs suddenly resulting in opposite pitch changes. If the system reset with each additional pilot input to continue overriding them. Pulling back means it dives further....... shameful Boeing.
FooBar Maximus most likely outsourced by managers and also approved by the managers over engineers screaming at them. Profit over quality is the motto of Boing
Duh! That's because the system DIDN'T reset each time the pilot responded. In fact, the system operated on an automatically resetting loop consisting of a check if all conditions were met (no flaps, autopilot off, AOA above a threshold value) and if so, it calculated the "run" duration-the amount of time it needed to drive the stabilizer-maximum 10 seconds, then pause for 5 seconds and start the loop again. If at any point the pilot used the electric trim, the MCAS operation would be abandoned no matter where in the loop it was, and would jump to the start of the 5 sec pause but remain suspended until the pilot stopped using the electric trim. Then it would execute the 5 sec pause and then begin the loop again. As typically happens, when people equipped only with common sense (the knowledge needed by common people for everyday living) try to understand much more complex subjects that require a substantial education in numerous fields, they end up with an understanding that is warped or simply false. But hubris makes one think that they can conduct an air crash investigation with just the common sense they have, and that's how the Seattle Times made a pudding out of just about everything concerning the 737 MAX; in this case they couldn't even understand Boeing's explanation of how MCAS worked. BTW, Boeing expected any pilot would intuitively respond to an uncommanded pitch change by instinctively using the elevator control to regain the pitch attitude and follow up with electric trim of the stabilizer to relieve elevator force. And that is exactly what the pilots did, they didn't need to even know that MCAS existed. One one flight the trim runaway occurred 24 times and the Captain countered it successfully the first 22 times. He (and the Pilot Flying on the other two flights) didn't switch off the electric trim system as Boeing expected, probably because they had never received ANY training on the runaway trim procedure; they gave zero indication that they had even heard of it. On one flight a spare pilot from another airline had received that training and told the pilots what to do. They all lived. On the other flights they played yo-yo with the trim runaways until, in one case, the pilot flying handed control to a FO and then failed to do the job of Pilot Monitoring, unfortunately, becaise the FO didn't even know how to use trim and allowed the runaway to take them to their grave. In the other case, the runaway was only activated 4 times. The first two were countered by the Captain. The last two he allowed to proceed unopposed, apparently in an attempt to trick the autopilot into engaging, not realizing how fatal that would become. If he had received the runaway training, he'd have known not to play around with a runaway condition.
P.S.: Never trust the news media to give you an understanding of aeronautical technical events or workings-they don't even have enough competence to vet their sources or even select valid ones, thus they ask baggage handlers if an airplane's design is safe-and can't comprehend the answer.
I think the root of the problem is that the MCAS continues to be active even when AOA and Speed are unreliable due to damage sensors or other defect. In Airbus there is a degradation in protecions when the aircraft is in a degraded flight law due to some failure. So basically the airbus is like "I am broken, you need to fly alone" and the Boeing "I am broken, but will continue to act like I am working"
Exactly. Both can have their issues, but I find the Airbus conceptually better. AF447 - Plane: "I've lost the speed sensors. Pilot, please take over and fly the plane". Pilot: "Aaah - I've forgotten how to fly the plane manually". Crash :( JT610 - Plane: "The angle of attack sensor (the broken one, I can't be bothered to double check with the working one) is telling me you are about to stall. I will force the nose down to avoid a stall". Pilot: "Aaah - what the hell is the plane doing, and why won't it let me to pitch up?". Crash :(
How else should it work tho without the sensor data going to flight control computer. There area also other characteristics the a/c has to meet before MCAS becaomes active. Also the stabilizer incremental commands are at different rates depending on AOA. The stab input is lower at high Mach number and greater at low Mach numbers.
Yess exactly
that's because Airbus has a lot more experience in flying with computers than Boeing
Is that a joke? Boeing makes fighter jets and has the Phantom Works division. Re: X-32, F-15, Bird of Prey, X-45, and more...
@@laurentiupopa5001
"I'm not going to go into the basics of a stall" ... IMMEDIATELY explains the basics of a stall 🤣😂🤣😂
Impossible NOT to.
@@dcpack yeah I just thought it was comical
Yeah, I think he meant to say"details" (or something like that) instead of "basics"
That's well noted... Hahaha
Not really. The basics of lift and loss thereof were omitted entirely.
I really hope all pilots are like you because I'm flying for my first time ever in 3 days
Enjoy!!
Lol hes better than almost every pilot trust me. This guy is legit
Notice how mentor did not say "yeah most are as good as me" he knows most pilots are like passengers now because planes fly themselves. It's sad really
I would go as far as saying he is one of the best pilots on the planet. The real deal.
Big detail regarding the MCAS function: The MCAS only uses a single AoA sensor to determine if the aircraft is in the right flight profile, and the pilots can select which of the two AoA sensors to use. Discrepancy in the two sensors is not detected by default (it was an option *that had to be purchased*) and even the display of the AoA readout on the PFD is not enabled by default.
On the Ethiopian Airlines craft, the AoA sensors were reading 3.2 and 7.2 degrees respectively, which would in any normal case be a condition to trip on a sensor failure and disable the control system entirely, which did not happen. There is also no cross-checking of the AoA reading with all other parameters of the flight profile, like airspeed, rate of climb/descent and attitude to determine if the measured AoA was even in a plausible region. The MCAS just blindly followed the reading of any sensor that it was connected to, regardless of it working properly or not.
The software update issued by Boeing actually enabled discrepancy checking and the 'AOA DISAGREE' warning on the EICAS for all 737MAX models.
That info is already established but its still a crazy design. Why would someone design a critical system like this? Its mind boggling..
Seems like they thought the MCAS pause they built into the system whenever yoke trim input was given would be enough, but the pause seems short enough that pilots may give up on countering it repeatedly during the incident because they think it isn't working and they move on to try something else because they haven't been trained with a memorized response to this exact condition.
Thank you for the comment. I am functional safety engineer (ISO26262). Even in the automotiv industry plausibility checks on input signals are mandatory, depending on the risk level (ASIL) of the safety goal concerned, wrt the system of study.
Same for cross monitorings between ECUs.
Another info that can be used as reference in order to disable MCAS is the air pressure, which decreases with the altitude. If air pressure is high (10^4
@@shakespear90 I agree most of your comment, but regarding to disable MCAS in high pressures as you said, I think that the MCAS is to avoid stalling during the take off, flying in manual mode, so the plane necessarily is in low altitude / high pressure. Both 737 Max accidents happened below 8000 feets.
In fact MCAS is to avoid stall during the climb stage after take off.
Im a current 767/757 pilot, and former 737 pilot. Very good and comprehensive explanation ! Well done sir.
I trimmed the B737F-200 and 300. The engines on the 300 was the first plat bottom versions. Then it was already so nose heavy that it could not fly empty. It needed at least 1800kg of ballast in the last two positions to take off. Granted the cargo door was heavy and also had to be placed in position A because the engines was in the way of the FMC. It could only go down hill from there with bigger engines in later versions.
I really wish journalists would watch videos like this before writing their articles. Really well explained and presented.
Exactly..the situation he stated is awesome
It makes me feel like I will fly again soon
There’s no money in not spreading Fear, Uncertainty, and Doubt.
Unfortunately that won't get them money
Everybody is scared of 737s now even though this could be fixed with more training and a software update
@@markmoreiras7649 No one thinks about the fact that thousands of flights have already been made with the MAX, without incident. It's absolutely right to ground it until we know more, but people are saying stupid things like "I don't trust Boeing, I'll never fly on a 737 again". I guess there is just no accounting for the stupidity of some people.
It seems the real issue is that MAX aircraft do _not_ react the same as other 737 variants, exacerbated by different behavior of autopilot _off_ behavior when pilot jerks the stick compared to other 737 variants. Clearly these differences would imply more and better training of pilots on MAX, even if they are previously certified or experienced with 737. But Boeing specifically indicated such extra training was not required (clearly, so as to make the new MAX a better economic proposition to airlines). The MAX does _not_ fly or react like other 737s at and near the stall limit and the MCAS fights with the pilot trying to push the nose down. If that pilot is just coming from hours on another 737 model, they might instinctively react in the wrong way on a MAX. At 30,000 feet, perhaps not an issue. At 2,000 feet? Catastrophe. I'm sure Boeing will continue to tweak and improve the MCAS software, but what really needs to happen is for pilots to better understand that MCAS-equipped aircraft are _not_ like other 737s, and adjust their procedures accordingly.
I'm an admittedly ignorant non-pilot, but it seems like in these situations it would be nice to have a master switch for "all software aids off, 100% manual flight". It seems like a 737 wouldn't need computer input to counter instability like a twitchy fighter, and you'd at least know that some digital ghost isn't fighting you.
I think this is the likely outcome. Boeing have tried to sell this plane as "another" 737, with (I think I'm right in saying) minimal to no retraining needed for pilots, and the MCAS system is at the heart of making this possible (and presumably legal).
I doubt there's anything wrong with the plane, just the pilots who are flying it. Maybe the system has issues, but I seriously doubt a properly trained MAX pilot would have any problems diagnosing and reacting.
I saw in another video that the 373 MAX basically introduced a physical alteration as a result of adding larger engines -- An upgrade that Airbus did on its I think A320 model shortly before. The problem was that Airbus had higher wings and could fit a larger engine under the wing. Boeing 373 wings were lower, and the engines already were as low to the ground as possible. Therefore, they had to raise the larger engines into and over the wing, which had a destabilizing aerodynamic effect that pitched up, raising risk of a stall. The solution to this (seemingly in replacement of additional physical stabilization, but I'm not sure) was the MCAS system, which was software intended to counterbalance this physical deformation induced off-balance. This software had a bug..... And we all know the result.
Hey, I know this is three years late but it isn't called 373, it's 737.😅
@AntoniosSpiliotopoulos
Due to severe behavioral issues, the Max was demoted to a 373.
Exactly the video I've been waiting for. Great work!
Mentour, I work as a mechanic for an airline in the US that currently has several 737 Max 8 in their fleet. I was just looking at the maintenance manuals, did a search option and found no mention anywhere about the MCAS system. Interesting.
You won't they hurried that sht and don't try to pull the breaker it will de-pressurize the cockpit and kill you like Hal 9000
@airplanegeek boeing deliberately hides mcas from everyone, since if people know about it they might be forced to train on mcas hence lots time and $$$ lost.:.
"ello ello - hmmm - what's this really HUGE actuator on the tail and a bearing, hmm must be something new ??? wonder what it leads to" - did you look at the tail circuits (wet and dry) diagrams :-)
@@ebaystars MCAS is a software algorithm that sensed from and controlled existing mechanics.
@@hoaivu2010the bad part about it they could have just put the mcas system in the differences training which is normal.
What is truly unconscionable is that Boeing didn't put out a general advisory - after the Lion Air crash - or seem to address the problem in any way. The lives lost are on Boeing's head.
Actually, they did. They reminded all 737 MAX pilots that there was a decades-old procedure that addressed a runaway stab trim condition. The FAA even followed up with an Airworthiness Directive that said the same thing. You must've missed all that.
@@petep.2092 Yes they did!
And from what little I know and have read about this whole debacle, the Ethiopian crew actually did follow the correct procedure (stab trim cut-off etc.) but since the MCAS malfunction happened at a lower altitude, they could not recover their aircraft and they crashed.
But none of this absolves Boeing of their responsibility in the tragic loss of life in any way and the fact that they initially blamed the pilots for their mishandling of the malfunction, the pilots who lost their lives and are not here anymore to defend themselves, when Boeing themselves tried to remove mentions of MCAS from certain documentation and tried to hide it from the regulators just goes on to show how subterranean their integrity and morals are.
Boeing may still make the best aircrafts in the world, but I and many others like me, would never feel safe stepping foot into a Boeing aircraft ever again. Thankfully, I live in India where most airlines go with Airbus (not that they are perfect in any way and yes, I know they have had their fair share of crashes but at least they haven't pulled the kind of shenanigans Boeing did, not to my knowledge)
I studied aviation safety as part of the flight management degree, and the first thing you learn about aviation safety is aircraft balance.
For example, you know what it's like to fly the B2 without the auto-trim system? The aircraft is EXTREMELY unbalanced, it's very difficult to fly without the auto-trim. It's a military plane with limited use, it's a great example of flying unstable aircraft.
Manufacturers purposely build their aircraft to be stable in the air. The fact that Boeing is selling an unstable aircraft to airlines for civilian use is astounding to be honest. The fact that the Max 8 needs an MCAS system to fly the aircraft and overcome bad stability is ASTOUNDING to me.
Yes, the pilots can err from their training, but an aircraft is not intended to be inherently unstable in-flight like the Max 8 and 9. That's literally the first lesson in aviation safety.
I think that the max is stable in normal flying conditions. In this specific, unusual condition there is a stability problem. I believe (please correct me) many aircraft that are considered to be stable do have unstable characteristics in some specific unusual conditions.
I believe that swept back wing aircraft are particularly difficult to recover from a spin, but this is a condition that an aircraft should never be in. Compromising other characteristics of the aircraft in order to mitigate this specific instability doesn't make sense.
@@JombieMann yes and no, most aircraft have unstable characteristics, but usually in a conditions like a spin or deep stall. However most aircraft are not unstable in the same phases of flight, as the Max 8 is. The Max 8's new LEAP engines actually move the center of thrust further forward than its center of weight. Thus it exhibits a characteristic that's sort of unique to the 737 family of aircraft, and unique to many other airliners (like the AB 320 or the Boeing 787).
That is what I call professional and accurate information! Thank you Mentour!
You and Juan Brown (Blancolirio channel) are the best Pilots in the world when it comes to
explaining things with no BS and undestandable to both Novices and
laymen alike.
Dont forget the little brown dog!! He’s pretty important too 👍🏼
First: Thx for that nice video! Amazing how well you can explain:)
Second:
I have some "insight" information from 737 pilots as my father is one of them. There is currently a message going around of a pilot explaining the lion air issue. Below I will share that message with you...for all of you with a little bit of background knowledge the message may be informative and interesting.
From a captain friend...
Boeing (and many posters) say "Hey, it's just a trim runaway. Do the drill and all is good." But this is not the simple trim runaway that the QRH contemplates. It starts with a stall warning stick shaker shortly after lift off. Close to the ground this will, and should consume both pilots undivided attention. After a number of seconds they realise that the airplane hasn't stalled and they start figuring out that they may have an airspeed and/or AOA problem.
This is a second problem to deal with on top of the first. And they can't shut the &%$#@ stick shaker off once they realise that it may be spurious. The PM will be frantically scanning the panel to try and find some clue what is going on. And this whole time, among the din of the stick shaker, crews concern for the airplanes flight path, and the confusing instrument indications, MCAS has been intermittently dialing in nose down trim. Not steadily, in a calm cockpit at altitude like the QRH contemplates.
But intermittently in the background of chaos, noise, and confusion. At some point, well past when it would have been timely, the task saturated PF realizes that the trim is working against him/her and the stab cutout switches get turned off. (hopefully)But the shitshow isn't over. Because of everything else going on, this took too long and the airplane is way out of trim. The Lion Air crew reportedly had 60 KG of back pressure on the yoke. Close to the ground, and relying on the lifting component of the underslung engines to help keep the nose up, the crew do not dare reduce power. Now the crew needs to manually trim the airplane, but the airplane is way, way off its trim speed. The B737 QRH makes reference to the large forces
that may be required to break free a servo clutch:
"3 If needed:Use force to cause the disconnect clutch to disengage. Approximately 1/2 turn of the stabilizer trim wheel may be needed.Note:A maximum two-pilot effort on the trim wheels will not cause a cable or system failure."Worse, the "Manual Stabilizer Trim" section of the Boeing FCTM talks about the air loads on a grossly out of trim stab requiring a speed change to reduce the force required to manually trim:
"Excessive air loads on the stabilizer may require effort by both pilots to correct mis-trim. In extreme cases it may be necessary to aerodynamically relieve the air loads to allow manual trimming. Accelerate or decelerate towards the in-trim speed while attempting to trim manually."Sweet Jesus how did this thing get certified?
A guy (or petite gal) has a 60 KG+ force on the yoke trying to stop the airplane from impaling itself into the hard ground just a few thousand feet below, and now he/she has to brute force trim the airplane as well, requiring involved coordination with the PM. Still with all the stick shakers, aural warnings, goofy instrument readings, and whatever else is happening to distract the crew and making communication almost impossible. It is not hard to see how quickly it becomes overwhelming. In addition to a fix for the airplane, if they keep the MCAS system (instead of designing a whole new wing or tail for the airplane), they will have to train the pilots who fly it to deal with its failure.
Right now, there is not a single Max pilot in the world who has been trained for this failure because - there isn't a single simulator in the world that can replicate it. But when they do, all those pilots that claimed "it's just a trim runaway" are going to have a very eye opening simulator session."
its essential to be able to access an off button to cut out wrong trim settings. like cut out for a runaway trimwheel - two switches below the pedestal woith the trimwheels. also erroneous data inputs caused this, forcing a fatal nosedown elevator setting.!!!
Tell Dad he has the Ethiopian and Lion Air crashes mixed up.
MCAS=(may crash any second)
😂😂😂
I called it MCRASH software.
@@new-knowledge8040 More like spaghetti code
I'm sorry Dave...Hal 9000 MCAS
stolen comment from Vox's video on the 737 max?
I couldn't take my eyes off that cute pup! 😍
the stick shake and warning makes you nervous even in the simulator. its scary
Matthew last time I went into McDonald's I ordered a thick shake, that made me nervous.
@@RB747domme I know right, the machine might be broken.
More scary would be to realize that you're in a full-blown stall just falling flat through the air. In relation the stick Shaker is quite reassuring
@@souocara38able at that point your fucked and you know it
It is confusing, but if you are confident on your actions then you should know exactly what to do
The dog STOLE the show :P
That dog has the LIFE!!
The GodPharaoh he always does :)
Only for those who have ADHD.
Ibn Khairuddeen (ابن خير الدين الألباني)
Or maybe ppl can enjoy boy man and his adorable dog.
0:25 - Oops! 😂😂😂
The red and green "navigation pillows" always make me giggle 😁
I think what we're going to find is that Boeing tried to save costs by grandfathering in changes on a 50 year old design, with engines that should have gone on a clean sheet - and band aid a solution with the MCAS. The 737 had reached it design limits (737-100 was designed as an aircraft low to the ground, with smaller engines to accommodate an attached ladder for passengers) and as more power was needed for each new stretched version, the dam finally broke. We'll see what the reports bring...
Wouldn't this be tragic if the entire engine placement and need for MCAS on the 737 Max was simply done just so the planes would fit inside existing hangers? - j q t -
Absolutely correct. Coudn' t have said it better. In order to really catch up with the airbus A320 , Boeing really needs to design a completely new airframe.
@@quill444 As far as I understand they wantes bigger more economic engines, but they did not want to redesign the whole airplane. Money money money. They would have needed a whole new design, new fuselage etc.
@@ninawallander515 absolutely true.
frankpinmtl
Boeing needs a new airframe that can fill the 737 role and still accommodate larger engines while being stable
Great video. I've been flying small planes since I was 16, and it's always a pleasure to listen to someone who really knows what he's talking about, and can relate it clearly. It's also very obvious why there are fewer than 300,000 airline pilots in a global population of 7 billion plus.
Great video and explaination; thanks! I believe that I understand and agree with the need for and design of the MCAS system, since the MAX versions are perhaps more difficult to wrestle out of an imminent stall, but what I do not understand, following the malfunction and crash last October, is why there was no IMMEDIATE RETRAINING for all MAX pilots to make sure that they could sucessfully disable this MCAS system if necessary. I feel that if Boeing and the insurance groups had endorsed this response, any future occurance of an MCAS runaway would have been non-fatal, and would have given ongoing data to the software engineers to allow them to eliminate this errant behavior from the system in future updates.
Cheers!
Sounds like a design change (moving engines) that resulted in the plane's stalling at full thrust if left to its own, so Boeing put in automation to pull the nose way down. Automation pulled the nose way down when it didn't need to do so, and the pilots didn't have enough time at low altitude to figure out what was going on and how to fix it before it hit the ground. Sounds like a good call to ground this plane!
No it was a design flaw on the engines. The engines were placed to high on the wing causing the plane to fly differently. MCAS was designed for military planes but Boeing installed it to correct the performance of the plane costing 350 lives. Boeing hid it from the pilots and the pilots didn't know how to overcome it. It was a huge scandal. Research it. I can't believe he didn't bring that up in his video. It sounds like he's covering for Boeing and I just lost my respect for him.
Sounds like you need an education in aeronautical engineering. Hopefully then you won't make up fake news.
Couldn’t they have just changed the takeoff trim settings for a bit more nose down?
How can you not pet that dog when he rolls on his back like that? He clearly wants to be in on the action.
Love the vids. Thank you.
Because he's communicating. Aviate>Navigate>Communicate>Pet Floofy Tum
He holds up model airplane at 4:18. Doggie says, "Chew toy!"
Glad to see the dog getting some attention this time! 😉
Doggie is living his (her?) best life!
Stall training was definitely the most unnerving part of training so far.
There's a lot of warning signs prior to a stall, but the actual stall itself is rather sudden.
It tends to induce panic so the first thing you have to do is learn to not panic, and remember the stall recovery maneuver.
Stalling an aircraft on purpose (which is done in training and sometimes for aerobatics) is somewhat different to when it happens unexpectedly though.
A regular stall, from what I experienced isn't so bad, but the second thing we trained was an accelerated stall.
That surprised me enough that I tried to recover before the instructor had finished inducing the stall in the first place.
The main thing that made it a lot more disturbing than a regular stall is that in the aircraft we were training in, an accelerated stall causes one wing to stall before the other.
Since this makes the lift asymmetric, the aircraft quickly rolls on it's side within a second or two. Rolling sideways rapidly when you're not expecting it is not a pleasant sensation...
Unfortunately I had to stop my flight training for financial reasons and it was quite some time ago, so I may be misremembering some aspects of it.
But in general the idea is to pitch the nose down and increase thrust. And if you experience a wing drop use the rudder to correct it, not the ailerons.
I'm sure it varies by aircraft, but the general idea of it is that the wings and tail are designed such that they shouldn't both stall at the same time.
Thus you should usually be able to recover using the tail.
Engine thrust may be something more specific to single engine prop aircraft, since the prop wash increases airflow across the wings and tail, which should increase control authority.
(it also induces roll, but that's not directly relevant.)
- worth noting that the specific aircraft I was doing this training in had a stabilator, or an all-moving tailplane. The trim actually adjusts a seperate flap on the horizontal stabiliser, while regular stick movenents cause the entire horizontal tail surface to move. This is the opposite to the example shown in the video, and no doubt has somewhat different implications in a stall (though I'm sure the general principles remain the same.)
Again, I could be remembering this incorrectly at this point. I've only had a few hours of flight training and it was several years ago now.
Still, the experience of stalling an aircraft and trying to recover from it is not something you forget easily. XD
"I'm not going to explain the basics of stall" *proceeds to explain basics of aerodynamic stall*
Haha. Top video mate keep it up.
Man I got used to seeing videos on this channel with the dog lying on the couch, asleep. Now, the dog just stole the show early on. LOL
Sorry my captain, but you miss the most import question - why Boeing makes Mcas as agressive like it is? Mcas is no addional securitiy feature, it is a essential trick to compansate the aerodynamic problems with the higher engine position. The stall behavior of the 737 Max is different to the predessors. Because of the jet blast directly under the wing the airlift collapses instantly without any warning on quite regular high angels of attack and this is the true story.
Good point
My related question, is why was Boeing allowed to launch a plane that needed MCAS to save itself?
It’s probably a marketing decision. They want to match A320 Neo’s “no extra training” marketing pitch.
Engines which are not located at center of gravity act like canard and creates additional lift which is effective at low speeds. This lift has an vector component which makes aircraft pitch up by itself and causes stall due to high AOA. MAX is an unstable aircraft at certain AOA and low speeds. This is not allowed in civil aircraft. That is why MCAS is so aggressive.
Actually, I think the important question is why MCAS is really needed? Is it to help pilots fly in certain situations, or is it really just a ploy to allow Boeing to claim that the MAX flies just like the other 737's and therefore does not require additional training. It seems to me that the fact that the characteristics are somewhat different simply requires training (not just of the hour on a iPad variety) and that is what they were really trying to avoid. It is a COMPENSATION system, NOT an Augmentation system. A software fix for a fundamental stability issue. Bad idea no matter how you try to paint it.
"Lose not thy airspeed lest the ground rise up and smite thee,"
My flight instructor was retired military and had thousands of hours in dozens of different types of aircraft. When he first started training me he was constantly reminding me that my first job was to "fly the damn plane". He would say "While you're attempting to troubleshoot that sputtering engine the ground WILL kill you!"
@@rwj1313 - Eastern 401 was a perfect example of that.
Thanks for this excelent video.
I've been in flight training for twelve years, and can't remember this issue
on the 757 of 767 (only verry little irilevant experience on 737-400)
Then again, as you describe, the 737-MAX is morely a total new airframe that just has the looks of its predecessors.
Having lot of experience in instructing on different types i can off record imagine what has been going wrong.
Mentor Pilot, you'd be an instructor of my heart.
Ahaha the doggie and the remote 🐕 Good timing 😂
Yeah now he has his puppy in his episodes, because few times his puppy wasn't in his episodes, so I reported him to the FPAA (Fluffy Pilots Aviation Association), so now he makes sure the puppy is in all his episodes. Trust me you don't want the FPAA coming after you.
Come for the planes, stay for the dog.
Thanks for the lesson on Bernoulli's principle. A stall in a plane is like a stall in a car. They both stop moving.
The big difference in stall training in the 172 is that when the plane stalls , you'll get a wing drop, nose drop and its relatively gentle. When you stall a 73Max the whole plane drops.
A good example of stall is 06:10 when your dog is laying on the couch, stalled and looking for a belly rub!!
Omg, I thought I was in love with the ginger, but that copilot! He is perfect. What I wouldn't do to be inside of that cockpit. You have not yet seen this stick shaker in action.
I know this is really serious and all, but your dog is freaking adorable
I have no aviation experience whatsoever but just wanted to comment on the instrumentation, warnings, human factors and the recent Ethiopian Airline tragedy.
1. In the video explanation of a stall scenario - it was commented on twice that the audible alert ‘Airspeed low’ would really wake you up.
2. It was also explained why with the nose pitched up increasing thrust would exacerbate nose up and maybe make it impossible to recover trim authority.
3. It was also stated the initial pilot action should be to restore trim to nose down trading altitude for airspeed.
4. This is where Human Factors kick in - in this scenario the instrumentation and warnings logic should recognise this as primarily a nose pitch up issue AND the audible warning should be ‘Nose Pitch Too High’.
5. In the scenario described in the video if the pilot was truly woken up by the audible alert ‘airspeed low’ he may be shocked into instinctively increasing thrust.
6. From what we know about the Ethiopian accident it appears that aircraft was about 1000 feet above ground - is that enough to recover from a stall even if pilot performance is 100%?
Apologies for verbosity.
Without some kind of rebuttal from an expert, it seems your point #4 is so obvious (after-the-fact).
Keep in mind that the airspeed was high and high airspeed at 1000 feet is way better than low airspeed at 1000 feet. I don't think the plane was actually in a physical stall situation in that there would have been laminar air flow across the wings. The MCAS system got erroneous information from the AOA sensor and would trim to pitch down. Keep in mind that pitch is not the same as AOA as was stated in the video. If any loaded passenger plane stalled at 1000 feet it would most likely literally fall to the ground before regaining enough airspeed to create enough lift to fly level.
I am a bit puzzled about one thing. The video clearly showed the computer system automatically running the trim during the stall demonstration. I believe this was a 737NG simulator since Boeing didn't produce 737max simulators right? Maybe the difference is that in the older gen the automatic trim worked only with the autopilot which is engaged once at a cruising point whereas the MCAS is "autopilot" for take-off flight phase.
The shift of the engines forward and up implies there was a significant change to the center of lift, the center of gravity, and the line of trust. Of course the center of gravity changes depending on the load placement within the plane. I would love to see something about how these factors changed between the models. Maybe Mentour Pilot has access to this information.
I love that dog, its always patient ,thanks for the video,well explained..
The puppy is so high altitude of cuteness😁😊😀
Yep! By the end of the video the bork is like 'yeahhhh dad cool flighty stuff but, mmm, lookat this couch...' **flop**
I don't think it's a puppy.....
Yes the dog is stabilised with nose pitched down😉
looks like he lost interest in the subject
I agree that the 737-Max (and commercial jets in general) need SOME kind of automatic system to push the nose down in case of a stall, HOWEVER here's why the way MCAS implements it is DANGEROUS and should NEVER have been allowed:
1) Activates if EITHER ONE of the AOA sensors detects a high AOA -- this creates the possibility of an inadvertent activation in case one of the sensors malfunctions, which is precisely what happened in the Lion Air crash (instead it should ONLY activate if BOTH sensors show a high AOA);
2) Operates solely through the trim control -- this should NEVER be allowed, the system should ALWAYS operate on the PRIMARY flight controls as well as the trim controls, so that the pilots will be instantly aware of its activation through the change in control forces (and so they can physically overpower it if need be);
3) As originally implemented, no limit as to how far forward it can trim the plane -- once again, this is EXTREMELY dangerous, because it means that a malfunctioning MCAS can COMPLETELY override ALL pilot inputs and the pilots CANNOT physically overpower it as they can a normal stick pusher (this is actually something which the FAA ordered Boeing to change immediately);
4) Intentionally hard to manually override/keeps reactivating after being overridden -- this is likewise EXTREMELY dangerous because a malfunctioning MCAS will keep reactivating and overriding pilot inputs despite being turned off, instead it should be made so that once the pilots turn it off (if they deliberately turn it off, that means there must be a good reason why), it would STAY off until they CHOOSE to turn it on again;
5) No allowance for low-altitude conditions -- the system will push the nose down regardless of altitude and so is capable of flying the plane straight into the ground (several black box recordings show the GPWS issuing "Don't sink" or "Pull up" warnings but the MCAS continued to push the nose down), instead it should be made so that the MCAS is SUPPRESSED when the GPWS activates (this ALONE would have prevented the Lion Air crash!)
What about Ethiopian? Looks like the same scenario here. The manual override is the issue. If I disengage, then I have disengaged! You musn't be overriden. Not having the full control of the plane for a pilot is bad. And a proper tutorial and training of the MCAS on the MAX series, not just a "yeah, that's the MCAS don't worry about it" kind of training.
Yeah, exactly! If you turn it off, then it MUST STAY OFF until the pilots CHOOSE to turn it back on (I actually talk about this in #4)! And I've actually found 2 more issues with MCAS:
6) As originally implemented, no limit on airspeed or nose-down pitch but ONLY angle of attack -- this is DOWNRIGHT CRIMINAL because it allows MCAS to put the plane into an extreme nose-down attitude, high-speed dive (the black box record for the Ethiopian flight showed that in its final dive it reached OVER THIRTY DEGREES NOSE-DOWN PITCH (!!!) and an airspeed of 375 KNOTS (the never-exceed speed is 340 knots IAS)), instead MCAS should be SUPPRESSED when the IAS exceeds 300 knots in cruise configuration or 250 knots in takeoff/landing configuration, and must be LIMITED AT ALL TIMES to a MAXIMUM nose-down pitch of 5 degrees; and this brings me to
7) At this extreme speed of 375 knots, the manual trim is so heavy that the combined strength of the pilot and copilot may not be enough to bring the plane out of the dive -- so, what is needed is a way to turn off MCAS (and other automatic trim systems) while still allowing the pilots to keep using the electric trim! (I personally call it the "Mooney mode" after the Mooney Bravo, which has a basic electric trim system WITHOUT all of those automatic systems!)
can we all admit that you did brilliant in the video but your dog definitely stole the whole show lol😍
Thumbs up if you want to have Mentour as a flight instructor ! Sir you're brilliant, passionate, and there is evidence that you like your fans and your job and this leads you to bring amazing content
beg to differ - *absolutely fantastic* content... :)
It shows that he has passion, he loves what he does. Mentour, you make a HUGE difference.
The Free Mind, Yes, this is teaching of the highest quality . . .
I understand what you are trying to do. However with how the 737 Max is designed no one will ever get me on that plane...
If the MCAS was simply a fail safe system - fine. However without it the Max couldn't even fly reliably. So MCAS failing or even simply turning it off would escalate the risk of a crash severely in my humble opinion.
nodlimax you are brainwashed and should not leave your house to avoid any danger 🤪
Yeah, I would call that a fundamental design flaw - not what you want on a passenger plane.
Turbo Pumped you 2 dumbasses no nothing about commercial aviation design yet are convinced you have all the answers based on UA-cam videos. This is a pilot training issue per professional pilots.
Chef Chefton blaming the pilot in this crash means you’re resigning commercial aviation to a “pilot as a single point of failure” model, shithead.
@@turbopumped6490 I agree with you. Obviously Boeing tried to solve a design problem with a software. Truth is the 737 airframe is outdated and can't be fitted with today's bigger engines. Boeing needs to design a completely new airframe to compete with the Airbus A320.
OMG look at that adorable DOODLE! Best part of the video.
Another thing I would like to point out is, it is easy to say "oh you just have to switch it off by using the trim cutout switches" - this is a terrible design for this type of computer assisted system, both the lion air and the ethiopian were in a post take off phase and not at cruise level high up, so there might be some TIME DELAY IN IDENTIFYING THE PROBLEM, and you might not have this time at low altitudes. I think it makes more sense to do it like airbus, where it turns off its protections automatically, when it detects that sensors are delivering totally different data, and the plane no longer knows which data is correct, thus handing over authority to the pilots.
Airbus actually never turns its protections fully off. Even when Sully put the one in the Hudson it still intervened and limited his inputs.
To have the sensors deliver different data, you have to provide at least two sensors for redundancy in the first place. The MCAS is feeded by only one of the AOA sensors!
Luca absolutely........
I guess the Airbus solution is too logical for Boeing Engineers. I might also have had a failsafe system that turns off MCAS when it is recognized that the pilot is trying to counter act the automatic inputs. At some point the control system should be able to identify a problem. But having redundant AoA instruments that are not checked against each other is basic control system design. It really looks even worse when Boeing was selling a redundant system as an option. What I don't understand is why the computer that controls MCAS was not able to look at the input from the standard redundant AoA sensor. I'm not a control systems engineer but was required to supervise the design of process control systems. That was 20 years ago and what I see going on with the 737 Max8 is criminal negligence. When your designing a system for control of a device that has lives directly at stake I would expect to error on the side of overkill. Not to have a built in AutoKill.
Luca - Yes...quick recognition and action required even with trim switches in CUTOUT position. Not much altitude when the MCAS failure occurred. Thrust levers likely full forward. Then you have to *manual* trim things back to normal climb. Likely requires action by both PF and copilot.
Great explanation of stalls and why MCAS is there. This DOES mean, however, that if properly trained these accidents (at least the Lion Air accident) should not have happened. MCAS should be turned off by the pilot.
Certainly, but Boeing also advertised the plane as needing basically no new training from previous 737 models.
At almost 50 years old, these videos make me want to pursue my childhood dream of becoming a pilot.
I don't see why you can't if you want it badly enough. Takes a few years, I've known of a few in their 40s to do it:) life experience is always desirable in any sector
Your next video should explain a stall during the take-off phase because it's an entirely different scenario if you don't have a altitude to play with. And do you believe MCAS should be allowed to override the pilots input.
Partyall his next video should be "Why Are pilots stalling airliners anyway"?
During takeoff you have the flaps at 15degrees. This is an intermediate position and it is used because a full flaps down would make the plane accelerate slower. The flaps help with much better lift although the critical angle of attack is reduced but the required angle of attack for the same lift is much lower. Also the flaps and the landing gear increase drag significantly so you need the engines at a higher power output . To prevent a stall it is not necessary needed to descend. A reduced angle of attack can mean also a reduced rate of climb or a level off. But if you stall it after take off only altitude can save you, if you are too low that's it. Reason for a take off stall can be a combination or one of the factors: weight distribution, incorrect flap setting, engine failure( one of the 2,4..), high air temperature, short runway, aircraft is too heavy, wrong horizontal stabilizer trim, pilot error, wind shear, icing, mechanical failures, etc
That is not a scenario. If you stall during a take off, you are dead. You saw the video: you need to trade altitude for speed. At take off you don't have altitude to trade. There is a reason most crashes occur during take off or landing. You are too close to the ground to make mistakes.
People, my point was, the procedures to PREVENT a stall seems straight forward when you're at 30,000 feet. Let's see what happens when you're at 4,000 feet during take off
Partyall you’re usually dead if a stall happens at that low of an altitude. Like they say speed is life. Altitude is life insurance. Some flight phases are more dangerous than others.
MCAS biggest flaw is their failure to give AUDIO and VISUAL warning to the pilots when it is activated, at LOW altitude any pilot will panic as the plane goes nose down without any warning and they had to fight to pull back while trying to figure out what caused it to dive in the first place. Secondly Boeing did not put a specific training on how to disable this system, because when pilot try to fly the plane manually, it will still dive! Thirdly equipment can malfunction and give wrong readout so they need redundancy, not just triggered by just 1 sensor like in Lion Air crash.
you're right the MCAS functionality is now definitely required.
What would be superbe is if the plane was PREVENTED FROM GOING NEAR A STALL condition requiring a nose dive courtesy of MCAS.
In other words flight controls should keep the plane away from a stall emergency. As I understand the new powerful thrusters should be dialed back way before an MCAS recovery kicks in.
(the failure of not enough AOA sensors is a separate topic)
👍🏻
Very nice, no need for further training,MCAS will take care of everything ...
MCAS could not make any extra noise or FAA would have denied the same type certificate for Max. The point of the same "type certificate" is that the operation of the plane must be the same. If 1964 version of 737 didn't make noise or show visual warnings, neither can Max.
Your shaggy dog is great ! Your pet dog is your best co-pilot ! Take him for a ride in a SR-71, then you can have breakfast in Tokyo, lunch in Madrid and dinner in Anchorage !
Best aviation channel on UA-cam. When I next fly abroad, I'm going to insist that I'm on one of your flights!
sure me too, come find me in the wing exit row
👍🏻
I have the highest respect. But why MCAS continues to dive the aircraft (always from a climb at low altitude) without cancelling. Once "correct" airspeed for AoA is achieved, it should just quit. But it doesn't it just keeps going. That's one thing, but the huge problem I have is that IT DECIDES when you are climbing at too steep an angle, and it's wrong. Both accidents happened with very steep 45-degree supersonic dives. MCAS gets 250 Kts from the pitot tubes and a certain AoA, but there is a problem it's software. It thinks you are at 40 degrees and just doing 150Kts. Pushes the nose down and doesn't switch off.
In the Lion air crash the AOA sensors were giving false readings, so that's why MCAS kept going. The plane thought it was still stalling due to the multiple AOA sensors each giving inconsistent data.
@@EdreesesPieces Yes. That's why I put "correct" airspeed in my comment. It's not correct data interpretation. MCAS will always think you are going too slow and will push the nose down further and further. But the Ethiopian crash is not related to AoA sensors. I'm saying that MCAS has a primary fault in interpreting AoA data. Boeing is working on a software fix for MCAS.
I don’t mean to be disrespectful, because I love the way you explain things, but I hope I can say I think you’re extremely attractive without making too much of a stir. Anyway, thanks for all that you do.
Yes, this is exactly the video I wanted to see!
hi
@@scum5 Back to the kitchen, huh?
She is not gonna hurt you, if she will know more about aviation, right?
But your words are already intended, to hurt, it seems like.
So take it easy.
They made a flyable plane unstable and dependent on auto intervention that pilots weren't trained for.
Genius! I heard also that production facilities were below par and workers said they wouldn't fly on one?
🤣🤣🤣
your dog is so lovable which makes it unable to concentrate wholly on your video😂
Sticking to the short landing gear on the 737 for 50 years now comes at a price.
The engines are too big for this short landing gear so their forward position leads to the undesirable need for the MCAS.
Excellent summary of the whole situation.
Why ALWAYS go complicated when you can simply GO SIMPLE, a pain in the ass , es
they actually had to put a longer nose gear on the MAX planes as well
B737 has always been sitting low on the ground, it is convenient and and makes maintenance easier for most of it's operators but can also come with it's drawbacks, but now I still question myself why they didn't make taller landing gears and nose wheel to have more room for the Engines under the wings and better ground clearance, this way they could of added a full landing gear door, that way the main wheels won't be exposed when they're in
@@Racko. even with the changes the bottom of the engines were only 19 inches off the runway
This is a great video, and seems to confirm my suspicion as to what may be aerodynamically wrong with the 737 max. It has already been well established that the new Max version of the 737 has greater tendencies for the nose to climb higher under heavy thrust conditions than previous models. There appear to be several factors that may contribute to this. When this plane first came out back in '69 or so, the point where the thrust from the engine met the surrounding environment (push point as I call it) was well behind the wing, and vertically very close to the wing's rotation axis with the long skinny JT-8 engine. When the larger diameter CFM 56 engines were later installed with 61" diameter fans, this "push point" was moved near the front of the wing, but it appears this was not enough to cause serious handling problems. Because the engines of the new Max version now have a fan diameter of 69 1/2", and are 21" longer, (124" vs 103") the engine and push points have been moved forward yet again. I recently overlaid 2D CAD drawings for both planes, and discovered that the exit point for the thrust from the bypass shroud has been moved forward by 22", and the exit point for thrust generated by the LP turbine has been moved a whopping 29" ahead of the old locations. The leading edge of the nacelle is now 13 1/2" inches ahead of the old location. The axial center line of both engines is roughly the same, with the additional diameter being divided equally above and below the old location. So from a purely mathematical perspective, as long as the plane is flying relatively flat at high speed, this horizontal shift shouldn't have much effect, but now that both the LP and bypass thrust points are much further forward than before, and the LP/bypass ratio has changed, the effects of this could be fairly dramatic under certain conditions. An example would be if the plane is oriented at a pitch of say 45 degrees, but flying at a low enough speed that it's trajectory is still roughly parallel to the ground plane, the downward projecting thrust from the engine would be would be at least somewhat deflected up and back and into the front of the wing as it traverses across the stationary air. This would in theory at least create additional lift at the front of the wing, inducing more pitch rotation forces. Using the same two CAD models but this time oriented with a 45 degree pitch, some interesting things started to appear. The first is that the top edge of the bypass shroud outlet is now horizontally or slightly above the leading edge of the wing, (18" higher than the older model), and exits very close to the wing's leading edge at this angle. How much effect this has on lift I'm not sure, but I was very intrigued by a photo of the A 320 NEO that showed where Airbus added long "ear" shaped extensions to the top (and bottom) of both the bypass shroud and LP exit point to deflect thrust away from the wing. (Boeing has a smaller one on the LP section only).
Another part of the equation that I noticed relates to the nacelles themselves in relationship to the axis of rotation. With the same models pitched at 45 degrees, the bottom of the nacelles are so much higher than the rotation axis of the wing root that they would act as lift devices for sure, and to some degree air brakes as well depending on severity of pitch. I measured the distance from the bottom front of the LEAP nacelle to the approximate centeroid of the wing root and found it to be 113" above, and 180" in front of the root center. The older version had measurements of 106" and 168" respectively, along with less surface area at the front of the nacelle where this potential leverage would be the greatest. At first I didn't think too much of it as the nacelles are rounded rather than flat planes, but the projected surface area of the nacelle is roughly 60% of the horizontal stabilizer, so there would be enough surface area to affect the dynamics of the plane. Regardless of whether my theories are correct or not, it is well known that this plane is not as aerodynamically stable as previous versions, as the implementation of MCAS was from what I've read, was apparently required for certification. Whether the plane is unstable enough that it truly requires MCAS to stay in the air, or whether it was only implemented to help the pilots deal with a few handling quirks under certain conditions, that I can't say. If my theory on thrust deflection is correct, then a relatively easy fix for this plane's stability issues may be to modify the bypass shroud for more lineal control of the thrust direction. If not correct, then there's likely no fix to the stability issues other than re designing the entire wing root to accommodate longer landing gear, which is not likely to happen.
Greg Miller: You are 100% correct and no matter how much spinning Boeing or the FFA continue to do you will still have a FLAWED AIRFRAME with the 737 MAX..Period. Changing the
programming on the MCAS and retraining pilots is nothing more than a bandage that will never fit correctly. If the airlines continue to buy the
737 MAX they will also be responsible, along with Boeing and the FAA, for any mishaps that inevitably will happen. Boeing has more than enough reserve cash on hand to
fix this problem correctly. If they don't the 737 MAX's should remain grounded permanently! (Edited) A flawed Airframe in relation to the larger and more powerful engines that were retrofitted to an old 737 Airframe. In my circles we call this: Boeing mickey-mousing just to save money!
Only the vertical position of the engines shoud influence the pitchmoment. The horizontal position should only influence the "airbrake" factor.
No. They are changing the amount of correction the MCAS makes from 6-7 degrees down to 2-3 degrees which will make a big difference.
@@watchgoose is this in relation to anything spcific? Lol.
NB.Greg seems to have missed his vector maths classes
@@flyingsquirrel2620 From a purely mathematically point of view, I agree that vertical height would be the biggest factor influencing pitch rotation forces under high thrust conditions. Theoretically the engines could be up at the nose (or tail) as long as they were vertically aligned with the wing's rotation axis. As far as the nacelles acting like lifting devices or air brakes, even if the plane were nearly vertical and acting like sails, I'm not sure they have enough surface area to make a difference as although they're wider than on the '56, they are also shorter and not as flat on the bottom. As for how the horizontal location of the thrust point could affect pitch rotation forces, my original hypothesis didn't explain how I'm thinking this may occur, and I've re written the last half of the post, as there may be multiple aerodynamic factors involved. The long and short of it is that it's well known that the Max has more of a tendency to pitch upward under power than previous versions, but the exact causes, we the public can only speculate
The way that the airspeed indicator reacts seem counterintuitive to me. I thought that a flashing display would have been more appropriate because it would draw your attention to it? Also, who the hell designed the MCAS system with only 1 Angle of Attack sensor, Boeing aren't building budget compact cars here !!! Even the throttle control on modern throttle-by-wire cars have 2 sensors which have to agree with each other, and cars don't fall out of the sky if they have a failure. I'm not a pilot or a designer, just applying common sense to this problem.
Modern cars with trac control may have 4 wheel speed sensors. My gm economy car has 4 of them and it's front wheel drive! Though you are right they typically monitor two for the speed of the car..... But the speed the of the other two wheels helps the car figure out which way it's moving relative to the steering wheel angle and helps the abs system keep the car stable under braking...... Yep though couldn't agree more. The lack of that second angle of attack sensor is endemic of cascading management issues at Boeing that compromised the safety of the aircraft. I sincerely hope they have aggressive restructuring occur. When I've looked over the features and issues of there 787, I find some of there design choices concerning. Things like the battery issue, which is understandable. It's disturbing that no one Considered a battery that much larger could catch fire though? Or the removal of grounding material in the composite wing as a cost cutting measure... Maybe it's never an issue, but it was originally there as a safety feature that was removed to save on cost.
13:40 Elton announced "stall stall", now that's training! He didn't hesitate.
It sounds like Boeing engineered itself into a corner & created MCAS as a band-aid solution. The Max 8 design was too far along to redo it when they found the stall problem, so MCAS.
It's interesting because Boeing's philosophy was that the pilot should always have ultimate authority and they seemed to have ditched that in the case of the MCAS, where the MCAS will overrule the pilots unless the electrical trim is physically turned off.
Your a good teacher,keep on teaching and I’ll keep on learning yes. Well thanks and see ya next time see ya bye bye.
Wow amazing detailed explanation of Stalling and the difference on NG and Max great job 👍🏽
its essential to be able to access an off button to cut out wrong trim settings. like cut out for a runaway trimwheel - two switches below the pedestal woith the trimwheels. also erroneous data inputs caused this, forcing a fatal nosedown elevator setting.!!!
It has fuselage from the 737,
Engines from the 787, flight controls from the A320 (the famous plane
where the automation led to crashes. Now 737 Max has taken that mantle)Boeing
should have done a clean sheet design as a replacement of 737 instead
of putting engines so big on an airframe meant for much smaller engine.They created and unstable plane and tried to fix it in software.While
this is an approach often used in fighter jets which are deliberately
made unstable so that they can change directions easily its not
something you do on a civilian airplane. A civilian pilot does not have
the reflexes of a fighter pilot to fix things if the computer is
misbehavingTo recap the plane was too small for the engines they
wanted to put on it. So they put the engines in a cantilevered position
so now the center of thrust was significantly away from the centre of
gravity and the plane had a tendency to pitch up and stall. To avoid
this they added MCAS which would pitch the nose down in case of a stall
detection. To detect the stall they used the AoA sensor and in a
freshman Fault Tolerant Computing bug depended on only one sensor when
they had 2. They made the warning light showing the AoA sensor is broken
an option (only American signed up for this option which is probably
why American hasnt had a crash). Then to make things worse they didnt
tell the pilots. Also in the NG if the auto trim was runaway pulling
back on the yoke would disengage the auto trim. With MCAS they changed
this. The auto trim would only disengage for 10 seconds and then MCAS
would add more trim and it would keep adding more and more trim till the
pilots could not counter even if they pulled the yoke all the way back.
Again a software bug. Further to make things worse THEY DID NOT TELL
THE PILOTS ABOUT THIS CHANGE. So the yoke maneouver does not work so the
only maneovour that works is disengaing the trim using the 2 cutoff
switches but this only disengages the Auto trim. If the plane is already
nose down it doesnt go back to normal trim. Now you have to pull back
on the yoke which was not working till a moment ago or spin two manual
trim wheels to get the trim back. All this is happening close to ground
as MCAS only engages at low speeds found at takeoff.Boeing could have avoided this in many ways1) Build a clean sheet design which is stable with the larger engines
2)
Failing that build a MCAS which is fault tolerant with multiple sensors
or can be countermanded by the pilot by pulling back on the yoke (This
is what they are doing now with the software fix). Not ideal for if the
pilot is really flying badly now he can stall the plane
3) Failing
that tell the pilots about the MCAS system, the change in the yoke
behaviour and have them go through difference training.They did not do 1 as it would cost too much money
They
did not do 3 as they wanted to avoid airlines having to train pilots
making the plane easier to sell. One of the reasons there are 5000 737
Max orders is that it needs no crosstraining to fly (officially)
They did not do 2 because of sheer laziness or stupidity in the engineering teamSo
the Engineering team is now fixing their error No 2. But the Exec
team's error No 1 and the Marketing team's error no 3 are still not
fixed.
Good information.
Oh my god! People died because of this??? Too cheap to put in mandatory sensor warning and sell planes without compulsory sensor malfunction warning???
The engines on the 737 MAX aren't the same as those on the 787. The engines on the 737 MAX are CFM Leap (the same as some A320neos) and the engines on the 787 are Rolls Royce Trent-1000 if I recall. They would never be able to fit those things on a 737...
And I love how you say, “the 500 first of you.” It sounds wrong but smarter at the same time somehow. The accent seals the deal. 👍
You have the reason for MCAS all wrong. It's not there for a different thrust line. It's there because LEAP nacelles in the forward position add pitch up moment at high AOA. The column force required to pitch becomes less or non linear. That violates certification requirements.
As an engineer, I've always suspected this to be true. Note that the larger nacelles would seem to generate more lift, further ahead of the CG, like canards. What we are not hearing is how severe the pitch up effect is, and whether it can result in a sudden stall, rather than something more manageable. Something seems wrong about the explanation that MCAS was merely added to avoid training requirements. If so, why was MCAS trim movement quadrupled at the last moment after flight tests, and FAA reportedly not informed about the change, and the ability to independently turn off auto trim while retaining yoke trim removed.
Mentour, you are THE MAN!! Fantastic video!
Another very interesting video from someone who really knows what they are talking about, I think your little dog went into a stall with all the aircraft talk
This channel has cured my fear of flying.
This channel has given me a slight fear of flying, for the first time in my life. Not because of any accident or malfunction. But because even though I'm interested in everything that has to do with engineering, I did not know a lot about flying, so I felt that the planes stay in the air sort of miraculously. A forward motion converted into an upward motion, that's about as deeply as I thought about it. But now that he has explained most of the things there are to explain, airplanes feel like just another mechanical and electronic device. And my experience with computers has been that you should never entirely trust such things.
Been waiting for this! Thanks for this quality informative content. Friday highlight😜
@mentour
I have a question
It is
Why don't pilots use trim to keep the nose levelled during takeoff in a 737max instead of mcas
I'm guessing that 737MAX is designed as there's no need additional training for original 737 pilots. However by moving the engine up and forward changes the weight and stall statistics meaning that it's a newly designed plane and need additional training to fly with. Also it takes years to validate a newly designed plane rather than just a upgrade to existing plane like A320 NEO. To make additional training unrequired and shorten the validation time, Boeing then add MCAS system so 737MAX can be considered as a upgrade to 737 rathen than a new aircraft.
So I think triming manually is the right way to keep the nose level down, but the statistics are different then original 737s.
Sorry for my bad English.
@@gilbertho1775 u didn't get it
Boeing put this system in the Max extremely quietly as if they really didn't want people to know it's there. Could this be described as an inherently unstable airplane after moving the engines forward with problems Boeing was trying to keep quiet?
Robin Sattahip FAA knew that plane was trash
Yes.
@@towmlvb3423 Having only flown Cessnas I didn't feel qualified to reach that conclusion so I phrased it as a question.
Whether they were "were trying to keep [an unstable design] quiet" is unknown. I have read comments supposedly from Boeing that they simply didn't think the "small change" was worth mentioning... there are so many details of a plane they didn't want to overload pilot's ability to grasp them all. (See how many examples of possibly flawed thinking, bad assumptions, etc. you might be able to find in that attitude!)
But IS the plane's design inherently unstable? It looks like it to me. A thought experiment: If Boeing had not included the MCAS in the 737 Max, could the plane have gained airworthiness certification?
@@captainlightbeam I have no doubt you are thinking along the right lines. Boeing may well have reached a phenomenal summit of stupidity by trying too hard to be too clever.
Loved your comment about “buffet alert” - “nothing to do with food” 😂
Hi Mentour, l just found this in my YT watch later list. l've always found your channel to be really interesting & informative.
ln this video l did cackle when you said 'buffet alert - this is nothing to do with food !'. 😂😂😂
As I understand it, the MCAS does not care if the two AOA (angle of attack) sensors show different values... But still wants to overwrite the pilots trim. This is bad engineering at every point...
They should learn from Airbus at this point. Airbus has more knowledge of the system. The computer on Airbus will recognise the AOA sensors were unreliable by comparing to other sets of data, and if the computer doubt, it will then isolate the control of computers with the control surfaces, and force the aircraft into DIRECT LAW, in which giving the pilot TOTAL MANUAL CONTROL of the aircraft (sometimes into a Computer Aided Alternate 1 and Alternate 2 Law)
However, those systems are not fool proof. Airbus experienced it the hard way. In the flight 888T incident, two out of three AOA sensors been froze up, but system logic rejected the working AOA sensor reading. But when correcting the aircraft maneuver approaching stall, the Flight Augumentation Computer detected that the AOA readings (incorrect) did not make sense with Airspeed and pitch data, which forces the aircraft into DIRECT LAW (manual mode; with msg "USE MAN PITCH TRIM" on PFD). Due to its a acceptance flight, and doing a stall protection test without proper abort speed (speed where if the system does not kick in, the pilots will stop the test and bring aircraft out of stall), the pilot overconfidence in the system, and due to the incorrect settings for the trim, the plane keep pitching up and climb until the aircraft entered a deep stall, and then it plunge into the sea.
@@junrenong8576 There is an "AoA Disagree" system actually.
@T.S.Dragon it has two. One on each side of the plane. Planes always have redundant systems so if one instrument breaks then there is a backup instrument that can be activated.
@T.S.Dragon They actually planned to roll out an update where the two senors will be taken into consideration. The problem was known widely after the LionAir crash. But the update got delayed (disagreements). Too late for the last plane to crash.
If what you say is true, then it's an error that gets a student fail at second year programming exam. At least when I was a student they learned us that critical data always have to be checked via redundant means. Double is standard, triple or quadruple when corruption leads to catastrophic fail. I'm a layman but as much as I understand stabilizer trim failure is catastrophic. So it's horrifying that some highly paid engineer actually designed automatic system that relies on one input only.
The Jackscrew was the cause of Alaska airlines flight 261 crash in 2000. They flew inverted for a while.
Poor maintenance (in fact, no maintenance) on the jackscrew was the cause.
"Flying inverted for awhile" stretches the facts. The crew seems to have intentionally rolled the airplane to inverted, and succeded in decreasing the dive attitude from around 75 degees nose down to (momentarily) about 9 degrees before it hit the water. "Flying" the airplane inverted wouldn't have been sustainable, as one engine stalled and flamed out due to disrupted airfow at the inlet (and the other likely would have, too). Got to applaud the effort, though.
@@ericcoleson7410 semantics.
@@djcatron11 I'll stipulate to that. Otoh, a thrown rock can be thought of as flying, but not in the same sense as a frisbee or kite. In reality, what Denzel Washington managed in the movie was to a frisbee as what the Alaska MD-80 crew managed was to a thrown rock; one not to be conflated with the other, despite use of the same verb.
During my days of flight MCAS stood for Minimum Controllable Air Speed. Just LOVE all the acronyms of aviation!
MCAS = More Customers Are Sacrificed
Hi mentour pilot, since you have access to a simulator, why don't you enable mcas during takeoff and see how well you do?
Seems to me that the MCAS is a sticking plaster to compensate for a less than ideal fundamental design problem. As an engineer I've seen plenty of examples of the use of electronics to hide or cover poor mechanical issues. Boeing have bastardized a design to reduce development costs and then added systems to deal with the inherent flaws. Presumably the FAA must have been fairly concerned about this if it stepped in to force this safety system onto Boeing. It also might explain why the FAA seemed reluctant to quickly ground the Max because they were in the middle of the problem.
How did some of the brightest engineers at Boeing neglect to understand what the change of engines would do to the 737 Max and its flight characteristics??????
@@jeffleverence4554 Money. Boeing needed to create a cheaper jet. They did it but it's clear that there are serious issues.
(Eyeroll). Every engineering task is a solution to a problem.
Jeff Leverence That is an excellent question...... Why were Boeing designers unwilling to consider the faults in their own design.....Once a project is invested towards, changing course becomes frowned upon. The project must go on at all costs, it must be completed since it’s already come this far..... On paper it may have seemed innocuous to increase engine size, then MCAS was added as a bandaid probably after the design was committed to.
@@ericcoleson7410 Agreed. However, using a sticking plaster approach rarely works well. The 737 Max has a design flaw and today that's unforgivable.
Damn i was really hoping for the buffet alert to tell me the flight attendant had the food ready.
HAhahausahsuauaha. OMG! Why am I laughing so much at this one?! xD
Sorry, it means you're about to lose your lunch.
Buffet alert=Margaritas🤣
What I heard from someone in the industry (unsure if he’s pilot or engineer, he posted in a forum) is that Boeing didn’t want to change the configuration of the plane after changing the engines, so they made the software team deal with it with computers. And the software team didn’t add a back up system for the sensors, so now when the sensors became faulty MCAS goes insane, and on top of that the way to shut down the MCAS has been changed without retraining the pilots. So the pilots in a panic tried the old method and failed
In fact MCAS is getting the data from only one AOA sensor, because it's not a primary flight control system ( for this it would be mandatory to have a redundancy) like in an fly by wire Airbus aircraft (they use the data of 3 AOA sensors).
If it's true what others report Boeing also didn't explain the system, some news channels say the only thing they gave to pilots was a 50 minute video about some differences between the NG and the Max. No special training.
@@simonm1447 .
You looked really rough during your live stream. You brush up very well. You are like a different man.
Your DOG is adorable!
Captain and First Officer🐶. They have the same color of hair 👍🏾👍🏾
Both from Northern latitudes...👍👍
ok but there was no F/O in this video
Maybe they went to the same barber.
You certainly are a deep thinker. Are you related to the pilots?
Richie Lee T 😂😂..no
Great explanation of "MCAS". The problem is that many Airline Pilots don't practice hand flying their aircraft on some kind of regular basis. If every time you fly you let the computer do all the flying, and you just monitor the system, as it is designed, and the Airline wants it for efficiency, you lose the quick response to unusual situations, like unintentional Stalls.
At any time in any phase of flight, every Pilot must know how the Aircraft feels, and sounds like in normal flight, and be aware of anything that is becoming not normal, and know how to correct a problem, or at least make a real problem not worse, by doing the wrong thing. And yes, there needs to be a quick way to turn off all computer control of the flight controls, to let the Pilot take total control, even if it takes a little more fuel, or time to get to the intended destination.
But I would still fly on a 737MAX with any Pilot with their 737MAX Training being up to FAA standards...
...well maybe I would not want to fly on 2nd, or 3rd World country's Airline, no mater where, or how the Pilots got their training.
The problem is that 737 Max is a rushed hack job and shouldn't even need an MCAS.
It matters not - the 737 Max has been exposed and is doomed.
I watch these videos exclusively to watch your dog. Huge fan.
I loved your reference to buffet Alert not relating to food 😁😁👍
i love when nouns and verbs are confused too
Buf-fay regards food. Buff-et regards wind effect. So the reference was incorrect but yes, cute in spite of.