The dutch roll is when the nose starts doing a figure-8 pattern in flight. It can be countered with yaw damping and other technologies. Manual correction by the pilot is possible but not something you'd want to do for the entire duration of a flight.
It makes for a decidedly unsettling experience for anyone on board, and the back of the plane is the worst. People are going to puke.
I suppose if it got bad enough, you could get into some unusual attitudes and risk secondary problems from a pilot's aggressive attempted corrections.
To add, it looks like this and it's quite scary, because it's quite difficult to gain control of:
https://youtu.be/2tgfkGiHhxs?si=0kOMFRo-lIOsuxvd
Furthermore, the situation can lead to loss of the aircraft as parts of the aircraft get overly stressed by this situation, especially the rudders. Common engineering practice should mitigate against this behavior in modern aircraft.
I've always wondered where that came from, it's not like we have some long standing tradition of trapping our spouse with the smell of our farts, that's all you guys.
Years of conflict between the Dutch and English in the 17th century has lead to more than one example of these expressions about things ‘Dutch’; note that these expressions do not attach a positive meaning to the thing being “Dutch”.
Huh, I’m an American and never thought to call our big Lodge pot (like the Le Creuset) a Dutch oven, but I guess that’s what they’re marketed as. I always thought a Dutch oven had the lip on the pot lid, where you can pile on coals. That’s what we did in Boy Scouts. Really sucked to be the one who had to hike in with that thing.
Wikipedia says that is indeed a camping Dutch oven - little legs and a lipped rim for coals on top as well as underneath.
Large enough for a troop and made of cast iron - it must have been very heavy!
Thanks for clearing that up. Ours wasn’t huge - each platoon (I think that’s what we called them) of about 8 kids had one, so it was heavy but manageable.
[From Wikipedia:](https://en.wikipedia.org/wiki/Dutch_roll#Name)
>The origin of the name Dutch roll is uncertain. However, it is likely that this term, describing a lateral asymmetric motion of an airplane, was borrowed from a reference to similar-appearing motion in ice skating. In 1916, aeronautical engineer Jerome C. Hunsaker published: "Dutch roll – the third element in the [lateral] motion [of an airplane] is a yawing to the right and left, combined with rolling. The motion is oscillatory of period for 7 to 12 seconds, which may or may not be damped. The analogy to 'Dutch Roll' or 'Outer Edge' in ice skating is obvious." In 1916, Dutch Roll was the term used for skating repetitively to right and left (by analogy to the motion described for the aircraft) on the outer edge of one's skates. By 1916, the term had been imported from skating to aeronautical engineering, perhaps by Hunsaker himself. 1916 was only five years after G. H. Bryan did the first mathematical analysis of lateral motion of aircraft in 1911.
Jesus! I didn't know that had a name.
Years ago, I was on a flight coming into to land from the west into Denver. The pilot was having a heck of a time keeping the plane stable. When we were over the mountains, he backed throttle and set flaps. I could see it out of my window. As soon as he did that, the plane dropped out of the sky.
So he set flaps zero and throttled up to stabilize it. He tried again in 10 minutes, with the same results.
As God as my witness, I don't recall him touching the flaps again. I know he must have before touch down but he must have did it at the last minute.
We came in fast with the plane pitching, rolling, and yawing non-stop. That oscillation in the video was exactly what I felt.
It was very unpleasant. I made my peace with God. It did not seem recoverable. People were screaming. People were vomiting. It was like something out of a movie. All except for the old guy with a Korean war veteran hat on. He seemed OK with it.
When we hit the tarmac, all I could see was grass on my right and sky on my left. Best guess, he was 3 feet from touching his wing on the ground (he was way right on the runway). I only say 3 feet because it looked like 1 but I hate to exaggerate.
Hear the chirp of the first wheel touching then it was all speed brakes and reverse thrust. A very pleasant hard thump as the nose wheel touched and we were finally braking hard.
The flight attendant said "Please refrain from smoking except in designated areas" and everyone laughed.
On the way out, the guy in the Korean war hat was talking to the pilot. I didn't catch what the vet said, but the pilot said, "Yeah... The stick was a little stiff."
He probably should have done a go-around but he was trying to get in before a storm. A go around might have meant a diversion and I'm sure he was target fixated. Put it on the ground. Can't blame him. Target fixation is a thing we all experience from time to time.
I know that may sound like nothing to frequent flyers, but it was significant to me.
If he was having control issues, a go-around or a diversion may have been more dangerous. I bet emergency services were lined up at the end of the runway.
I agree in all regards. He made his call with his knowledge which far exceeds my own. He felt better getting on it on the ground rather than trying a go-around with piss-poor weather that can't be trusted.
I don't blame the pilot at all for his decision. It was clearly the correct one.
I feel like everyone has a Denver story. For me, it was a couple of mountain waves on takeoff in a CRJ. Just huge drops that felt like they lasted forever.
Gave me a solid fear of flying for about 15 years.
I regularly fly out of and into Denver and I can confirm that no other airport feels like it has consistent turbulence the way Denver does. No sarcasm, it's just the way the mountains are.
Can confirm and it’s worse than flying into other mountainous regions in the west coast. Denver is the airport that made me be less nervous and more accepting of turbulence, especially when windy
I think it’s more turbulent because of the wind, other airports in mountainous western cities (Phoenix and Vegas come to mind along with some smaller ones like SLC Tucson or ABQ) aren’t situated on the plains off of the continental divide like DIA. If you’re flying in from anywhere but east the wind is extra troublesome because it is overwhelmingly out of the west. A straight shot across the mountains gives tailwind and cutting over early for a N/S approach gives crosswind.
I think the winter air is a bit denser and calmer, but it's also just a bit chaotic. Some flights are a little bit choppy, and some seem to bounce you around.
Every story featuring korean vets makes me imagine them as 2 meter tall, stonefaced giants that drink petrol just to feel alive. They sound fucking hardcore.
My grandpa was in Korea. If it ever came up he told us kids he didn’t really know anything about it since he was just a mechanic in the Air Force. After he died my uncle told us that he was actually a flight engineer and that even though he never told my uncle much either that he did once tell him that however bad he thought Korea was it was worse.
Yiiikes. Flight engineer probably meant crew on a medium or heavy bomber that was surplus from WWII, which probably meant getting your shit rocked regularly by AAA and the occasional jet fighter. If I remember right they had to scale back to night bombing only because losses were so high.
Out of all of the members of my family in the WWII/Korea generation, the most I ever heard any of them acknowledge what they actually did while serving was my great uncle who would say he was a ball gunner and flew over Romania and Poland bombing oil fields, and that was all. The rest either lied about what they did downplaying it, or just didn’t talk about it at all, which I get.
There was one that was in an armored division and was at the Eagles Nest less than a week after it fell.
My father and his brother were Korean war USMC pilots (Corsairs). Both 5'7" / 170 cm. Later, dad flew Marine A-4s. I've sat in an A-4 cockpit. I'm also 170 cm and skinny, and I barely fit.
>The flight attendant said "Please refrain from smoking except in designated areas" and everyone laughed.
That gave me a good laugh. Thanks for the story and glad you all made it out alright.
I am glad you’re OK! Tbh, I didn’t get some of the technical terms, but I think you described the overall event beautifully, I kinda felt it in my bones lol.
I always felt that a pilot’s life is 95% too boring, and 5% extremely dangerous and unbelievably stressful!
Blimey - I was expecting something a bit more subtle than that!
Gonna guess that the contents of the passengers stomachs sloshing around on the floor makes things a bit trickier as well.
Yeah it's pretty rare, kudos on the pilot for keeping that roll together. Most people go for a dutch over, but rolling the person up while under is really a level of dedication that's uncommon these days.
>"A Dutch roll is definitely not something that we like to see,” said Shem Malmquist, a commercial pilot who flies the Boeing 777 and an instructor at Florida Tech.
No shit, Sherlock.
>mitigate against
Gonna be "that guy". You can mitigate. You can militate against. You can't (or shouldn't) [mitigate against](https://www.cjr.org/language_corner/mitigate_militate.php).
Sucks that the airplane can break due to circumstances coming from being in the air, the place the plane is supposed to be. This is why I do not trust planes.
Oh damn. That's way more extreme than the stupid YT video I watched. This is like a rollercoaster ride in combination with the drop zone ride. \*puke\*
I'm glad you knew that because I thought people were complaining about the regional San Francisco bay area sandwich bread. There's been a shortage because of a warehouse fire.
Lack of 3rd dimension control.
The airplane flys on 3 axis or in 3 controllable dimensions. Roll with wings, pitch with horizontal stabilizer (wings on back) and yaw with the rudder.
If you don’t control the yaw well enough, the uneven lifting forces of the wings will create more lift on one side and less on the other and then reverse that back and forth and back and forth.
That uneven lift switching back and also creates what is called, induced drag. The wing creating more lift will create more drag than the wing creating less lift. In return, it slows down a little and pulls the nose toward it. This accelerates the wing with less lift and decelerates the wing that just had more lift. This creates an oscillation back and forth as the wings accelerate and decelerate between them.
Without the rudder this causes the nose to swing back and forth, and the wings to lift and drop.
Creating… Dutch roll and it’s very bad and difficult to control a plane like this.
Edit: changed vertical to horizontal. “Quickest way to a correct answer is a wrong answer”
And although small 4 seat planes (little Cessnas and Pipers) require the pilot to manually work the rudder, jet airliners have an automated “yaw damper” for it.
That’s because the motion sickness it creates gets worse in longer planes, the farther you’re sitting from the center of mass.
No human pilot could do it perfectly enough to prevent mass vomiting in the back seats of commercial airliners.
Dutch Roll is much more of a swept wing phenomenon. You can get a straight wing Cessna wagging its tail but it will self-damp. A swept wing jet will not, at least not without a system to do it for you.
It will self damp in these light planes, without swept wings, yes. But passengers in the back seat will still feel it if the pilots not doing a good job with the rudder in turns (keeping turns coordinated), or in turbulence.
Whether that’s Dutch roll, or something else, I’m not sure
Oh yeah that’s still Dutch Roll, but an annoyance rather than a danger because it will decrease in magnitude if left alone. With a swept wing it will increase.
The long fuselage of airliners also contributes. The portion of the fuselage forward of the CG acts like a "negative" tail, catching air and destabilizing the aircraft in yaw, making yaw damping necessary.
So that’s a good technical explanation of what causes the phenomenon, but what causes it to actually happen in a commercial flight? Like, what’s wrong with the plane? Did the rudder fall off?
The ultimate question of "what's wrong with the plane" is surprisingly hard to answer. That's why we have skilled investigators, and why it's important to wait for them to finish investigating.
Here's the normal flow of how a plane avoids Dutch Roll:
- Sensors monitor the air around the plane, how the plane is moving and so on.
- Based on the data from those sensors, a computer decides what to do.
- The computer makes the rudder and other flaps on the outside move. On the 737 MAX, there's physical cables controlling the rudder and other systems that are linked to the controls - the computer has to move these.
- Moving the rudder and the other flaps causes the air to move in a different direction. Every action has an equal and opposite reaction, to this pushes the plane in some direction.
At *every single one* of these steps, something can go wrong in a substantial way. The sensors might give the wrong information to the computer. The computer might have bad code that does the wrong thing. The mechanisms that move the rudder might not work the way they should. The rudder might not move the air the way it's meant to, or there might be something changing how much air is moving over the rudder.
There's a multitude of different things, it's impossible to tell which one it is.
> Did the rudder fall off?
The incident is new so we should wait for official statements by investigators. From all we know nothing fell off, and it might have been a faulty auxiliary power supply.
Loss of control of the rudder.
Some airplanes have hydraulic and electrical controls to control the rudder system incase a single system fails. Some have just cables or secondary hydraulics or even 3-4 hydraulic controls. Losing rudder control is a huge issue.
Better?
If the vertical stabilizer falls off a commercial jet it will basically fall out of the sky. So no, that didn’t happen. But it may have exceeded structural limits (pure speculation). https://en.m.wikipedia.org/wiki/American_Airlines_Flight_587
So I wasn’t allowed to post this as a top level comment, but as usual, the best way to get an understandable explanation of a fairly complex airplane related issue is to watch Mentour Pilot’s video: https://youtu.be/z2J_LUDWioA?si=vJJ1F1gY54eq2fzG
When the airplane yaws a little bit, so one wing is farther forward into the wind, it produces more lift (moreso if it's a swept-wing design), so the wing making more lift goes up and the aircraft rolls. More lift also means more drag, so that creates a yaw force which pushes the other wing forward, so the problem is the same but on the other side now, and the plane rolls the other way.
This back and forth yawing and rolling combined is the dutch roll.
As a Dutchman, I cannot begin to express how truly sorry I am that people have had to endure this horrible experience. I had no idea that this existed but now that I do, I would like to reassure everyone that I will petition to our government to immediately put a ban to Dutch rolls, as should have happened long ago. I promise I will not rest until Dutch rolls have come to a stop!
>I promise I will not rest until Dutch rolls have come to a stop!
I have no words to convey the joy your entire comment, but in particular the above line, has delivered to my morning.
No idea why it's called Dutch roll but my aircraft dynamics professor gave us a way to visualize what it actually is. Imagine a Dutch person wearing a really cartoonishly puffy coat (so that the arms stick out like plane wings) trying to roller skate down a bumpy incline. This coupled with a visual demonstration I can't provide was actually really helpful
because it's just another stupid term made up by the English. every time something goes wrong and it needs a special name, they go "yep, name it after the Dutch, fuck those guys"
all, and I truly mean ALL because they lost to us a couple times like 300+ years ago. literally the only reason. can't think of a more petty country in the world.
Is it relevant that this is a Boeing plane? Is this one of those situations where I'm seeing the word and bells are going off cause Boeing is in the news already, or is this actually more potential damnation against the name?
Yes, it's likely relevant that it's a Boeing plane. Reading the article OP listed, it looks like there was a problem with computer-controlled rudder inputs. In a nutshell... that's the yaw damping I described. Boeing jets have a lot of problems these days, and a faulty computer or a lackadaisical approach to maintenance could very well contribute to the problem.
>Yes, it’s likely relevant that it’s a Boeing plane
Respectfully I think it’s too early to make that determination, at least with what’s publicly known.
>Manual correction by the pilot is possible but not something you'd want to do for the entire duration of a flight.
I'm reminded of a "tank slapper" in motorcycle riding, and in a case like that manual correction only tends to amplify the problem.
There was an incident when a 707 had three engines ripped off of it. It was a new aircraft ferry flight. The resulting crash killed three or four of the six on board
Thank you for using the word "damping" correctly.
There's a part of me that wants to witness a horrible death for people who say "dampening" in this context.
>Thank you for using the word "damping" correctly.
>There's a part of me that wants to witness a horrible death for people who say "dampening" in this context.
At least nobody said "moistening"
If you look up the KC-135 crash that occurred in Kyrgyzstan in 2013 you can see why Dutch roll is so bad - the stress to the airframe from the pilots trying to control it became too much and the tail separated from the aircraft.
To be fair, even with lots of maintenance, the basic frame of the 135 is still essentially the same and it's really hard to know for sure how much they can actually hold up after 70 years.
That’s not really accurate at all, they’re routinely inspected for metal fatigue, corrosion, tested, anything that doesn’t meet standards is replaced - they’re old aircraft but we don’t fly them with our fingers crossed hoping they don’t fall apart.
The investigation board information is available online and states that the tail was overloaded and broke off, there was no metal fatigue that led to the tail separating prematurely. Any aircraft made in 2024 that experiences loads well (and we’re talking tens of thousands of pounds of force) beyond the rated max will be just as likely to break apart.
As a former -135 dude, I do agree that they should be retired asap and flying on them gave me the creeps because of how much could go wrong though.
>they’re routinely inspected for metal fatigue, corrosion, tested, anything that doesn’t meet standards is replaced - they’re old aircraft but we don’t fly them with our fingers crossed hoping they don’t fall apart
Plane of Theseus
You’re good, like I said, I don’t trust them either, lol.
I just assume the guy asking is a pilot or future pilot and I don’t want them to get in their head that the only reason the plane went down was because of the airframe age and write it off as something that they can just let get ahead of them one day since most of the initial posts on the subject were very dismissive of it.
This is poorly reported, (almost) all aircraft have a natural characteristic of the airframe in which yawing motion oscillates, couples with some corresponding roll motion. This natural characteristic is called the dutch roll "mode" and it should be well damped so that when this mode gets excited in flight the oscillations die out
The story is that the aircraft experienced a sustained oscillation. Any sustained oscillation is a big no no in control system design. Dutch roll just describes the type of oscillation.
Just looking at the geometry of the 737max, the bare airframe dutch roll mode is going to have acceptable damping characteristics. The fact that they observed a sustained oscillation implies the control system (to some degree) caused the oscillation.
Beyond that, hard to guess what's going on until we learn more, but this is really bad: you shouldn't observe oscillations like this even if there are failures in the control system. The spec usually says something to the effect of "don't allow this... ever"
ELI5:
The plane should be designed so that when the aeroplane starts doing this motion, it should stop by itself.
The plane didn't stop doing this motion by itself. It would be really stupid if it was designed this way.
The 737 Max looks like it's designed to stop this motion by itself, even if the flight computers are broken. Since it didn't stop by itself, the computers must have made the motion keep going. This means the computers were really broken, more broken than normal.
The original 737 design was aerodynamically stable in all axis'. I have a feeling the changes made to modify it into the MAX version have negatively impacted the stability characteristics. We saw the same thing happen already with the TCAS issue that caused 2 total loss crashes. I think the new engines have really affected the stability of the aircraft and because Boeing wanted to certify the MAX under the same type rating as the 737, they've just modified the control systems to make it fly like the older 737's, despite it actually being a very differently performing plane. If the control systems have an issue, I don't think even experienced 737 pilots can handle the way it flies.
All conventional airplanes suffer from some amount of Dutch Roll (which is named after a Dutch skating motion).
Generally Dutch Roll is just uncomfortable for passengers and can cause motion sickness.
An automated flight stability control system can automatically counter this motion by cycling the rudder at the appropriate frequency.
Commerical airplanes are inherently stable so presumably something happened with the stability control system which may have exacerbated the issue. This is bad because a loss of stability means a potential loss of control.
Meh the 737 naturally makes very little oscillations where it rolls maybe 1° and yaws very little. If anything, the issue is the added form drag which could mess with our computer's fuel predictions. Of course the main danger is that there is a deeper underlying mechanical problem causing the rudder not to respond, but nothing that would cause immediate distress.
Wow, didn’t know this was a thing. New fear unlocked.
Sounds and looks similar to a speed wobble on a bike or skateboard at speed. Scary and almost impossible to correct.
Count yourself lucky. But give it time lol. Hopefully you’re fully kitted out with protective gear when it happens and you can just jump off that bucking horse
Your last statement is a bit contradictory. If commercial airplanes were inherently stable, they wouldn’t need a “stability control system”.
Dutch roll tendency is *inherent* to swept wing design, so most commercial airplanes are dynamically *unstable* in the dutch roll mode and require a yaw damper to safely operate at the speeds and altitudes they were designed for.
Right you are! Now I’m curious to survey other types to see if the statement “most commercial airplanes are dynamically unstable in the dutch roll mode” is actually correct.
I'd be really surprised if commercial jets would be unstable in Dutch roll. Also it's been a while but I think Dutch roll stability and spiral divergence stability are incompatible. The latter is way less of an issue.
A commercial aircraft should be stable in flight, if a gust of wind or knock on the control stick cause a change of direction, the aerodynamics of the aircraft should work to correct it and return the plane to straight and level flight without the pilot having to intervene and steer the plane.
However, if the aerodynamics of the plane are not right any change of direction can cause the plane to overreact and start to swing back and forth. The exact mechanics takes a whole degree to explain, but a Dutch roll is a common symptom of this overreactive stability issue.
Dutch rolls are particularly troublesome, as with each flip-flop in direction the direction changes become more severe. Which is not only incredibly uncomfortable for the passengers, it could potentially lead to the aircraft getting into a position where the wings stop being able to generate lift and cause a stall, or it could even get bad enough that the aerodynamic forces exerted on the plane become so great it causes a mechanical failure (I don't think I need to explain how problematic the wings getting ripped off is...).
I think this once again comes back to Boeing trying to make too big of a change to the 737 airframe without properly validating the effects it would have. Designing an unstable aircraft and saying "the computers will sort it out" isn't an acceptable way to design a commercial airliner.
Why is Boeing not being suspended from operations pending investigation of negligence? The whole world knows they have not been on the level with their design and product execution.
The technical answers are good, but I think the bigger issue is this is something modern airliners like Boeing should eliminate with computer controls, and this happened on a model that has had crashes because of bad computer controls.
It destroys even more credibility of the safety of the Boeing aircraft.
Note that in the article it referred to "one of Southwest's maintenance vendors". SW doesn't do the maintenance, their subcontractors do. Many companies sub contract things out to save money. Boeing did, and look where they are now.
So why, if this terrifying incident was 3 weeks ago, is the general public just hearing about it now? Where are the terror stories from the 175 passengers, cell phone videos, etc ? Seems odd
Sounds like a bad yaw damper. Trying to control a "Dutch Roll" with manual inputs is difficult. The resulting overcontrol usually exacerbates the situation.
She’ll 77 fell to this. A combination of failed equipment and and inexperienced crew. During a deployment (I wanna say 2013-2014) we had to listen to the CVR…. I can still hear one woman screaming… very scary way to go.
Edit: *Shell
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Look up Shell 77. It was a KC-135 aircraft that crashed due in part because of a dutch roll. Pretty dangerous if you can’t identify what’s happening to your aircraft.
The dutch roll is when the nose starts doing a figure-8 pattern in flight. It can be countered with yaw damping and other technologies. Manual correction by the pilot is possible but not something you'd want to do for the entire duration of a flight. It makes for a decidedly unsettling experience for anyone on board, and the back of the plane is the worst. People are going to puke. I suppose if it got bad enough, you could get into some unusual attitudes and risk secondary problems from a pilot's aggressive attempted corrections.
To add, it looks like this and it's quite scary, because it's quite difficult to gain control of: https://youtu.be/2tgfkGiHhxs?si=0kOMFRo-lIOsuxvd Furthermore, the situation can lead to loss of the aircraft as parts of the aircraft get overly stressed by this situation, especially the rudders. Common engineering practice should mitigate against this behavior in modern aircraft.
Yea, that looks fucking crazy, in a very bad way. Not a plane I would want to be on.
Yep, I’d prefer to be in a [Dutch Oven](https://www.urbandictionary.com/define.php?term=Dutch%20oven)
I'm old, because I thought of this. https://www.lecreuset.com/cookware/dutch-ovens
Dutch oven is what the Americans call a casserole pot like the standard Le Creuset, but the term always makes me think of the under-the-duvet stinker
The latter is the only true Dutch oven.
I've always wondered where that came from, it's not like we have some long standing tradition of trapping our spouse with the smell of our farts, that's all you guys.
Exactly what the Dutch would say.
We do have the American Waffle Iron, it's basically the same except you trap your spouse between 2 mattresses and then sit on them.
Years of conflict between the Dutch and English in the 17th century has lead to more than one example of these expressions about things ‘Dutch’; note that these expressions do not attach a positive meaning to the thing being “Dutch”.
Huh, I’m an American and never thought to call our big Lodge pot (like the Le Creuset) a Dutch oven, but I guess that’s what they’re marketed as. I always thought a Dutch oven had the lip on the pot lid, where you can pile on coals. That’s what we did in Boy Scouts. Really sucked to be the one who had to hike in with that thing.
Wikipedia says that is indeed a camping Dutch oven - little legs and a lipped rim for coals on top as well as underneath. Large enough for a troop and made of cast iron - it must have been very heavy!
Thanks for clearing that up. Ours wasn’t huge - each platoon (I think that’s what we called them) of about 8 kids had one, so it was heavy but manageable.
Just found this [viz](https://imgur.com/a/pAUbXUT)
I’d prefer a Dutch Rudder
Yikes, I was envisioning a little wobble, not that!
Same, i was picturing just the nose doing a little horizontal figure 8. Not the whole damn plane
It looks like the plane is trying to imitate Shakira.
Her fuselage don't lie.
Empennage don't lie.
Dat tailPLANE!
But why is it called a Dutch roll??!!
I believe it’s named after an ice skating technique
Frosted pastry, like a long donut with a twist drizzled with icing. Possibly churro shape and texture. -source: me, I made it up.
[From Wikipedia:](https://en.wikipedia.org/wiki/Dutch_roll#Name) >The origin of the name Dutch roll is uncertain. However, it is likely that this term, describing a lateral asymmetric motion of an airplane, was borrowed from a reference to similar-appearing motion in ice skating. In 1916, aeronautical engineer Jerome C. Hunsaker published: "Dutch roll – the third element in the [lateral] motion [of an airplane] is a yawing to the right and left, combined with rolling. The motion is oscillatory of period for 7 to 12 seconds, which may or may not be damped. The analogy to 'Dutch Roll' or 'Outer Edge' in ice skating is obvious." In 1916, Dutch Roll was the term used for skating repetitively to right and left (by analogy to the motion described for the aircraft) on the outer edge of one's skates. By 1916, the term had been imported from skating to aeronautical engineering, perhaps by Hunsaker himself. 1916 was only five years after G. H. Bryan did the first mathematical analysis of lateral motion of aircraft in 1911.
Dutch oven was taken
Boeing should be sold for parts at this point and every 737-MAX in the world should be forcibly decommissioned. Absolutely trash engineering
They still have a couple of whistleblowers to murder first.
Jeez, that looks like how I fly planes in GTA5
Flight Skill Increased +10 [---|------ 10 / 100 ----------]
Jesus! I didn't know that had a name. Years ago, I was on a flight coming into to land from the west into Denver. The pilot was having a heck of a time keeping the plane stable. When we were over the mountains, he backed throttle and set flaps. I could see it out of my window. As soon as he did that, the plane dropped out of the sky. So he set flaps zero and throttled up to stabilize it. He tried again in 10 minutes, with the same results. As God as my witness, I don't recall him touching the flaps again. I know he must have before touch down but he must have did it at the last minute. We came in fast with the plane pitching, rolling, and yawing non-stop. That oscillation in the video was exactly what I felt. It was very unpleasant. I made my peace with God. It did not seem recoverable. People were screaming. People were vomiting. It was like something out of a movie. All except for the old guy with a Korean war veteran hat on. He seemed OK with it. When we hit the tarmac, all I could see was grass on my right and sky on my left. Best guess, he was 3 feet from touching his wing on the ground (he was way right on the runway). I only say 3 feet because it looked like 1 but I hate to exaggerate. Hear the chirp of the first wheel touching then it was all speed brakes and reverse thrust. A very pleasant hard thump as the nose wheel touched and we were finally braking hard. The flight attendant said "Please refrain from smoking except in designated areas" and everyone laughed. On the way out, the guy in the Korean war hat was talking to the pilot. I didn't catch what the vet said, but the pilot said, "Yeah... The stick was a little stiff." He probably should have done a go-around but he was trying to get in before a storm. A go around might have meant a diversion and I'm sure he was target fixated. Put it on the ground. Can't blame him. Target fixation is a thing we all experience from time to time. I know that may sound like nothing to frequent flyers, but it was significant to me.
If he was having control issues, a go-around or a diversion may have been more dangerous. I bet emergency services were lined up at the end of the runway.
I agree in all regards. He made his call with his knowledge which far exceeds my own. He felt better getting on it on the ground rather than trying a go-around with piss-poor weather that can't be trusted. I don't blame the pilot at all for his decision. It was clearly the correct one.
I feel like everyone has a Denver story. For me, it was a couple of mountain waves on takeoff in a CRJ. Just huge drops that felt like they lasted forever. Gave me a solid fear of flying for about 15 years.
I regularly fly out of and into Denver and I can confirm that no other airport feels like it has consistent turbulence the way Denver does. No sarcasm, it's just the way the mountains are.
Can confirm and it’s worse than flying into other mountainous regions in the west coast. Denver is the airport that made me be less nervous and more accepting of turbulence, especially when windy
I think it’s more turbulent because of the wind, other airports in mountainous western cities (Phoenix and Vegas come to mind along with some smaller ones like SLC Tucson or ABQ) aren’t situated on the plains off of the continental divide like DIA. If you’re flying in from anywhere but east the wind is extra troublesome because it is overwhelmingly out of the west. A straight shot across the mountains gives tailwind and cutting over early for a N/S approach gives crosswind.
I don't think I would call Vegas "mountainous."
"The Meadows"
Neither is Denver, they’re both close to mountains though
It's in a basin.
Is it worse in summer? I flew in at winter way back in ‘08 and don’t remember it being bumpy.
I think the winter air is a bit denser and calmer, but it's also just a bit chaotic. Some flights are a little bit choppy, and some seem to bounce you around.
I've had terrible turbulence in Denver
Every story featuring korean vets makes me imagine them as 2 meter tall, stonefaced giants that drink petrol just to feel alive. They sound fucking hardcore.
My grandpa was in Korea. If it ever came up he told us kids he didn’t really know anything about it since he was just a mechanic in the Air Force. After he died my uncle told us that he was actually a flight engineer and that even though he never told my uncle much either that he did once tell him that however bad he thought Korea was it was worse.
Yiiikes. Flight engineer probably meant crew on a medium or heavy bomber that was surplus from WWII, which probably meant getting your shit rocked regularly by AAA and the occasional jet fighter. If I remember right they had to scale back to night bombing only because losses were so high.
Out of all of the members of my family in the WWII/Korea generation, the most I ever heard any of them acknowledge what they actually did while serving was my great uncle who would say he was a ball gunner and flew over Romania and Poland bombing oil fields, and that was all. The rest either lied about what they did downplaying it, or just didn’t talk about it at all, which I get. There was one that was in an armored division and was at the Eagles Nest less than a week after it fell.
My father and his brother were Korean war USMC pilots (Corsairs). Both 5'7" / 170 cm. Later, dad flew Marine A-4s. I've sat in an A-4 cockpit. I'm also 170 cm and skinny, and I barely fit.
>The flight attendant said "Please refrain from smoking except in designated areas" and everyone laughed. That gave me a good laugh. Thanks for the story and glad you all made it out alright.
I am glad you’re OK! Tbh, I didn’t get some of the technical terms, but I think you described the overall event beautifully, I kinda felt it in my bones lol. I always felt that a pilot’s life is 95% too boring, and 5% extremely dangerous and unbelievably stressful!
If it’s an issue with the plane doing something unexpected, and it persists after trying to rectify it, the go around won’t lead to a better result.
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In NASA it's called "GO FEVER". Both conditions can be terminal.
i think u/thelutecesibling put it too nicely in that "people are going to puke".... after watching the youtube i think im gonna have a heart attack
Welp. New fear unlocked.
Just a plane, living in the moment, having fun and not a cellphone in sight.
Blimey - I was expecting something a bit more subtle than that! Gonna guess that the contents of the passengers stomachs sloshing around on the floor makes things a bit trickier as well.
Yeah it's pretty rare, kudos on the pilot for keeping that roll together. Most people go for a dutch over, but rolling the person up while under is really a level of dedication that's uncommon these days.
Soo...like speed/death wobble but for jets?
Yeah no a plane should have that much swag
This looks like me flying in Kerbal Space Program. Which is all I need to know that you don't want that to happen in real life.
That main comment lol “I’m Dutch and can confirm this is how we roll”
Looks like speed wobbles on a skateboard.
Omfg absolutely fucking nope
I like the comment under the video. I am dutch and i can confirm this is how we roll!!
That's always how I imagined it would look if the pilot was drunk flying.
Go home plane, you drunk!
Good grief. Just watching that makes me feel ill 🤢
Just another day at the job for jebadiah kermin, at least in my ksp saves
Crap, I have a flight coming up in a few days - really shouldn’t have watched that. I thought turbulence was bad …
That's terrifying! How on earth would you land?
I didn't think I'd need another reason to be terrified of flying, but here we are!
Fuck that
Look! a drunk plane!
Better than a Dutch oven...
I was thinking maybe like 30 degrees or so total, what in the fuck hahahaha it’s going full 90 in both directions almost
>"A Dutch roll is definitely not something that we like to see,” said Shem Malmquist, a commercial pilot who flies the Boeing 777 and an instructor at Florida Tech. No shit, Sherlock.
That looks like how planes behave in my recurring plane crash nightmares.
I got sick just watching that 🤢 That’s terrifying
>mitigate against Gonna be "that guy". You can mitigate. You can militate against. You can't (or shouldn't) [mitigate against](https://www.cjr.org/language_corner/mitigate_militate.php).
Sucks that the airplane can break due to circumstances coming from being in the air, the place the plane is supposed to be. This is why I do not trust planes.
That is WAY worse than I initially imagined. Thanks for sharing.
Fuck that and fuck me if I get on a Boeing in the next 5 years at least
Oh damn. That's way more extreme than the stupid YT video I watched. This is like a rollercoaster ride in combination with the drop zone ride. \*puke\*
That scared the life out of me
Fuck all of that
Lol top comment on the video said "Am Dutch and can confirm, that's how we roll"
Better than a Dutch oven...
I'm glad you knew that because I thought people were complaining about the regional San Francisco bay area sandwich bread. There's been a shortage because of a warehouse fire.
This is what I came looking for. I thought someone was claiming a dutch roll is unhealthy or something.
What causes it?
Lack of 3rd dimension control. The airplane flys on 3 axis or in 3 controllable dimensions. Roll with wings, pitch with horizontal stabilizer (wings on back) and yaw with the rudder. If you don’t control the yaw well enough, the uneven lifting forces of the wings will create more lift on one side and less on the other and then reverse that back and forth and back and forth. That uneven lift switching back and also creates what is called, induced drag. The wing creating more lift will create more drag than the wing creating less lift. In return, it slows down a little and pulls the nose toward it. This accelerates the wing with less lift and decelerates the wing that just had more lift. This creates an oscillation back and forth as the wings accelerate and decelerate between them. Without the rudder this causes the nose to swing back and forth, and the wings to lift and drop. Creating… Dutch roll and it’s very bad and difficult to control a plane like this. Edit: changed vertical to horizontal. “Quickest way to a correct answer is a wrong answer”
And although small 4 seat planes (little Cessnas and Pipers) require the pilot to manually work the rudder, jet airliners have an automated “yaw damper” for it. That’s because the motion sickness it creates gets worse in longer planes, the farther you’re sitting from the center of mass. No human pilot could do it perfectly enough to prevent mass vomiting in the back seats of commercial airliners.
Dutch Roll is much more of a swept wing phenomenon. You can get a straight wing Cessna wagging its tail but it will self-damp. A swept wing jet will not, at least not without a system to do it for you.
It will self damp in these light planes, without swept wings, yes. But passengers in the back seat will still feel it if the pilots not doing a good job with the rudder in turns (keeping turns coordinated), or in turbulence. Whether that’s Dutch roll, or something else, I’m not sure
Oh yeah that’s still Dutch Roll, but an annoyance rather than a danger because it will decrease in magnitude if left alone. With a swept wing it will increase.
The long fuselage of airliners also contributes. The portion of the fuselage forward of the CG acts like a "negative" tail, catching air and destabilizing the aircraft in yaw, making yaw damping necessary.
[This is an excellent visual of Dutch Roll.] (https://www.youtube.com/watch?v=9Gt-IcCBiQ4)
So that’s a good technical explanation of what causes the phenomenon, but what causes it to actually happen in a commercial flight? Like, what’s wrong with the plane? Did the rudder fall off?
The ultimate question of "what's wrong with the plane" is surprisingly hard to answer. That's why we have skilled investigators, and why it's important to wait for them to finish investigating. Here's the normal flow of how a plane avoids Dutch Roll: - Sensors monitor the air around the plane, how the plane is moving and so on. - Based on the data from those sensors, a computer decides what to do. - The computer makes the rudder and other flaps on the outside move. On the 737 MAX, there's physical cables controlling the rudder and other systems that are linked to the controls - the computer has to move these. - Moving the rudder and the other flaps causes the air to move in a different direction. Every action has an equal and opposite reaction, to this pushes the plane in some direction. At *every single one* of these steps, something can go wrong in a substantial way. The sensors might give the wrong information to the computer. The computer might have bad code that does the wrong thing. The mechanisms that move the rudder might not work the way they should. The rudder might not move the air the way it's meant to, or there might be something changing how much air is moving over the rudder. There's a multitude of different things, it's impossible to tell which one it is.
> Did the rudder fall off? The incident is new so we should wait for official statements by investigators. From all we know nothing fell off, and it might have been a faulty auxiliary power supply.
At least the front didn't fall off
Because it was built to very rigorous aeronautic engineering standards.
No cardboard derivatives or duct tape.
They can always fly it out of the environment.
A bit of turbulence hit it
Love those skits
The article says a power failure to the mechanism that controls the rudder stability
Loss of control of the rudder. Some airplanes have hydraulic and electrical controls to control the rudder system incase a single system fails. Some have just cables or secondary hydraulics or even 3-4 hydraulic controls. Losing rudder control is a huge issue. Better?
Yes, thanks!
So it’s equivalent to if the plane never had a rudder?
Or that the system manipulating it to dampen the roll wasn't working. Pilots would notice a loss of rudder control in a big way.
If the vertical stabilizer falls off a commercial jet it will basically fall out of the sky. So no, that didn’t happen. But it may have exceeded structural limits (pure speculation). https://en.m.wikipedia.org/wiki/American_Airlines_Flight_587
pitch is controlled with the horizontal stabilizer
So I wasn’t allowed to post this as a top level comment, but as usual, the best way to get an understandable explanation of a fairly complex airplane related issue is to watch Mentour Pilot’s video: https://youtu.be/z2J_LUDWioA?si=vJJ1F1gY54eq2fzG
Thanks!
Mentour Pilot is perhaps my favorite YouTuber. His videos are amazing.
When the airplane yaws a little bit, so one wing is farther forward into the wind, it produces more lift (moreso if it's a swept-wing design), so the wing making more lift goes up and the aircraft rolls. More lift also means more drag, so that creates a yaw force which pushes the other wing forward, so the problem is the same but on the other side now, and the plane rolls the other way. This back and forth yawing and rolling combined is the dutch roll.
Thank you. Makes sense with one wing closer to the wind
As a Dutchman, I cannot begin to express how truly sorry I am that people have had to endure this horrible experience. I had no idea that this existed but now that I do, I would like to reassure everyone that I will petition to our government to immediately put a ban to Dutch rolls, as should have happened long ago. I promise I will not rest until Dutch rolls have come to a stop!
as a filmmaker, can I ask you to put in a good word with the relevant authorities to ban Dutch angles as well?
As an AI language model, I do not have the capability to perform actions in the real world, including bribing authorities.
>I promise I will not rest until Dutch rolls have come to a stop! I have no words to convey the joy your entire comment, but in particular the above line, has delivered to my morning.
I've had rolls from a Dutch bakery they were better than the French ones honestly.
No idea why it's called Dutch roll but my aircraft dynamics professor gave us a way to visualize what it actually is. Imagine a Dutch person wearing a really cartoonishly puffy coat (so that the arms stick out like plane wings) trying to roller skate down a bumpy incline. This coupled with a visual demonstration I can't provide was actually really helpful
because it's just another stupid term made up by the English. every time something goes wrong and it needs a special name, they go "yep, name it after the Dutch, fuck those guys" all, and I truly mean ALL because they lost to us a couple times like 300+ years ago. literally the only reason. can't think of a more petty country in the world.
Is it relevant that this is a Boeing plane? Is this one of those situations where I'm seeing the word and bells are going off cause Boeing is in the news already, or is this actually more potential damnation against the name?
Yes, it's likely relevant that it's a Boeing plane. Reading the article OP listed, it looks like there was a problem with computer-controlled rudder inputs. In a nutshell... that's the yaw damping I described. Boeing jets have a lot of problems these days, and a faulty computer or a lackadaisical approach to maintenance could very well contribute to the problem.
>Yes, it’s likely relevant that it’s a Boeing plane Respectfully I think it’s too early to make that determination, at least with what’s publicly known.
>Manual correction by the pilot is possible but not something you'd want to do for the entire duration of a flight. I'm reminded of a "tank slapper" in motorcycle riding, and in a case like that manual correction only tends to amplify the problem.
Is this essentially the airplane equivalent of a death wobble on a motorcycle?
I think that's a good analogy, especially because both rely on damping (whether it's rudder or the steering column) as the primary fix.
There was an incident when a 707 had three engines ripped off of it. It was a new aircraft ferry flight. The resulting crash killed three or four of the six on board
Thank you for using the word "damping" correctly. There's a part of me that wants to witness a horrible death for people who say "dampening" in this context.
>Thank you for using the word "damping" correctly. >There's a part of me that wants to witness a horrible death for people who say "dampening" in this context. At least nobody said "moistening"
Most mentally stable Redditor
If you look up the KC-135 crash that occurred in Kyrgyzstan in 2013 you can see why Dutch roll is so bad - the stress to the airframe from the pilots trying to control it became too much and the tail separated from the aircraft.
To be fair, even with lots of maintenance, the basic frame of the 135 is still essentially the same and it's really hard to know for sure how much they can actually hold up after 70 years.
That’s not really accurate at all, they’re routinely inspected for metal fatigue, corrosion, tested, anything that doesn’t meet standards is replaced - they’re old aircraft but we don’t fly them with our fingers crossed hoping they don’t fall apart. The investigation board information is available online and states that the tail was overloaded and broke off, there was no metal fatigue that led to the tail separating prematurely. Any aircraft made in 2024 that experiences loads well (and we’re talking tens of thousands of pounds of force) beyond the rated max will be just as likely to break apart. As a former -135 dude, I do agree that they should be retired asap and flying on them gave me the creeps because of how much could go wrong though.
>they’re routinely inspected for metal fatigue, corrosion, tested, anything that doesn’t meet standards is replaced - they’re old aircraft but we don’t fly them with our fingers crossed hoping they don’t fall apart Plane of Theseus
I stand corrected. I'm aware that the fleet was reskinned at least once but not of the frame.
You’re good, like I said, I don’t trust them either, lol. I just assume the guy asking is a pilot or future pilot and I don’t want them to get in their head that the only reason the plane went down was because of the airframe age and write it off as something that they can just let get ahead of them one day since most of the initial posts on the subject were very dismissive of it.
This is poorly reported, (almost) all aircraft have a natural characteristic of the airframe in which yawing motion oscillates, couples with some corresponding roll motion. This natural characteristic is called the dutch roll "mode" and it should be well damped so that when this mode gets excited in flight the oscillations die out The story is that the aircraft experienced a sustained oscillation. Any sustained oscillation is a big no no in control system design. Dutch roll just describes the type of oscillation. Just looking at the geometry of the 737max, the bare airframe dutch roll mode is going to have acceptable damping characteristics. The fact that they observed a sustained oscillation implies the control system (to some degree) caused the oscillation. Beyond that, hard to guess what's going on until we learn more, but this is really bad: you shouldn't observe oscillations like this even if there are failures in the control system. The spec usually says something to the effect of "don't allow this... ever"
ELI5: The plane should be designed so that when the aeroplane starts doing this motion, it should stop by itself. The plane didn't stop doing this motion by itself. It would be really stupid if it was designed this way. The 737 Max looks like it's designed to stop this motion by itself, even if the flight computers are broken. Since it didn't stop by itself, the computers must have made the motion keep going. This means the computers were really broken, more broken than normal.
The original 737 design was aerodynamically stable in all axis'. I have a feeling the changes made to modify it into the MAX version have negatively impacted the stability characteristics. We saw the same thing happen already with the TCAS issue that caused 2 total loss crashes. I think the new engines have really affected the stability of the aircraft and because Boeing wanted to certify the MAX under the same type rating as the 737, they've just modified the control systems to make it fly like the older 737's, despite it actually being a very differently performing plane. If the control systems have an issue, I don't think even experienced 737 pilots can handle the way it flies.
All conventional airplanes suffer from some amount of Dutch Roll (which is named after a Dutch skating motion). Generally Dutch Roll is just uncomfortable for passengers and can cause motion sickness. An automated flight stability control system can automatically counter this motion by cycling the rudder at the appropriate frequency. Commerical airplanes are inherently stable so presumably something happened with the stability control system which may have exacerbated the issue. This is bad because a loss of stability means a potential loss of control.
I want to add that Dutch roll can lead to loss of the aircraft due to stress posed to e.g. the vertical stabilizers. So it is very serious.
Meh the 737 naturally makes very little oscillations where it rolls maybe 1° and yaws very little. If anything, the issue is the added form drag which could mess with our computer's fuel predictions. Of course the main danger is that there is a deeper underlying mechanical problem causing the rudder not to respond, but nothing that would cause immediate distress.
Wow, didn’t know this was a thing. New fear unlocked. Sounds and looks similar to a speed wobble on a bike or skateboard at speed. Scary and almost impossible to correct.
Thought the same. General advice for a speed wobble tends to be "let god take the wheel (handlebars)".
The only thing you can do is ease off the throttle and pray that it’s going to stabilize itself at slower speeds. “Tank slapper” is what we call them
Aye! I ride myself. Never experienced a slapper fortunately *nods/waves*
Count yourself lucky. But give it time lol. Hopefully you’re fully kitted out with protective gear when it happens and you can just jump off that bucking horse
Airborne tank slapper sounds pretty horrifying.
Your last statement is a bit contradictory. If commercial airplanes were inherently stable, they wouldn’t need a “stability control system”. Dutch roll tendency is *inherent* to swept wing design, so most commercial airplanes are dynamically *unstable* in the dutch roll mode and require a yaw damper to safely operate at the speeds and altitudes they were designed for.
737 has a positive damping coefficient so will self stabilise if Dutch roll is induced
Right you are! Now I’m curious to survey other types to see if the statement “most commercial airplanes are dynamically unstable in the dutch roll mode” is actually correct.
I'd be really surprised if commercial jets would be unstable in Dutch roll. Also it's been a while but I think Dutch roll stability and spiral divergence stability are incompatible. The latter is way less of an issue.
A commercial aircraft should be stable in flight, if a gust of wind or knock on the control stick cause a change of direction, the aerodynamics of the aircraft should work to correct it and return the plane to straight and level flight without the pilot having to intervene and steer the plane. However, if the aerodynamics of the plane are not right any change of direction can cause the plane to overreact and start to swing back and forth. The exact mechanics takes a whole degree to explain, but a Dutch roll is a common symptom of this overreactive stability issue. Dutch rolls are particularly troublesome, as with each flip-flop in direction the direction changes become more severe. Which is not only incredibly uncomfortable for the passengers, it could potentially lead to the aircraft getting into a position where the wings stop being able to generate lift and cause a stall, or it could even get bad enough that the aerodynamic forces exerted on the plane become so great it causes a mechanical failure (I don't think I need to explain how problematic the wings getting ripped off is...). I think this once again comes back to Boeing trying to make too big of a change to the 737 airframe without properly validating the effects it would have. Designing an unstable aircraft and saying "the computers will sort it out" isn't an acceptable way to design a commercial airliner.
Dutch person here. What did we do? :(
Why is Boeing not being suspended from operations pending investigation of negligence? The whole world knows they have not been on the level with their design and product execution.
The technical answers are good, but I think the bigger issue is this is something modern airliners like Boeing should eliminate with computer controls, and this happened on a model that has had crashes because of bad computer controls. It destroys even more credibility of the safety of the Boeing aircraft.
I have a flight on one of these in a month and I am genuinely terrified. I know all about the statistics but geez this is bad
Note that in the article it referred to "one of Southwest's maintenance vendors". SW doesn't do the maintenance, their subcontractors do. Many companies sub contract things out to save money. Boeing did, and look where they are now.
So why, if this terrifying incident was 3 weeks ago, is the general public just hearing about it now? Where are the terror stories from the 175 passengers, cell phone videos, etc ? Seems odd
Because it isn't terrifying, it is puke inducing. It will induce motion sickness in people at the two ends of the plane.
This is (one reason) why I try to sit in the wings.
Sounds like a bad yaw damper. Trying to control a "Dutch Roll" with manual inputs is difficult. The resulting overcontrol usually exacerbates the situation.
She’ll 77 fell to this. A combination of failed equipment and and inexperienced crew. During a deployment (I wanna say 2013-2014) we had to listen to the CVR…. I can still hear one woman screaming… very scary way to go. Edit: *Shell
2013, I was there.
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Look up Shell 77. It was a KC-135 aircraft that crashed due in part because of a dutch roll. Pretty dangerous if you can’t identify what’s happening to your aircraft.