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Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

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Re: Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

#91

Post by VBprogrammer »

The 737, at least in classic guise, was traditionally very stable in Yaw. Unusually so because the swept wing jets usually require additional yaw damping because the geometry naturally means on yawing one wing gets longer and the other gets shorter as seen from the point of view of the airflow. So much so that the Yaw damper on the 737 was not on the minimum equipment list for dispatch. On other aircraft like the 757 having one of the two yaw dampers out of service limited dispatch to return to a maintenance base (from memory so it might not be exactly that).

I'll keep my eye out for the report on this one because I'm not convinced the initial reporting tells the whole story. It's not unheard of for pilots to damage otherwise perfectly serviceable aircraft through in-proper rudder application - American Airlines Flight 587 being a horrible example.

Re: Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

#92

Post by brandall10 »

blakesterz wrote: post #4

"Dutch Roll is a coupled out of phase movement of the aircraft as result of weakened directional stability (provided by the vertical tail and rudder), in which the aircraft oscillates around its vertical as well as longitudinal axis (coupled yaw and roll)." That sounds pretty scary. I wonder why it wasn't bigger news when it happened last month?

Just flew a Max from Denver to Mexico City a couple days back.

It was mostly uneventful, but as we were preparing to land the aircraft banked hard to the left and began to experience something akin to this...like it hit a sudden pocket of turbulence at the apex of the turn and began to pogo around.

It was minor and far from inducing damage to the vehicle, but in that moment remembered where I was while clenching my body for a few nervous seconds until we eased out of the turn.

Re: Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

#93

Post by somenameforme »

bradleyjg wrote: post #53
amarant wrote: post #25

It kinda bothers me that airlines are still placing orders for new Boeing airplanes. Taking delivery of old orders is one thing, since they can't really back out of those, but placing new orders implies that some level of trust remains for this company, and I just don't see how that makes any sense at all?

Do you think your car (or bike) is safer or more dangerous than the least safe Boeing plane in service?

These numbers are always pretty BSy because the big dangers in flight are take-off and landing. Comparing distances just completely obfuscates everything for no real gain.

You can illustrate this clearly with some sort of reductio ad absurdum. Imagine we have an interstellar ship traveling many trillions of miles, but that blows up 90% of the time. If you look at it in terms of this same deaths/mile metric it'd still be way safer than driving, but obviously it isn't - which emphasizes that the metric is misleading.

The most reasonable way would be safety per average trip, with some sort of multiplier for particularly long or particularly short trips. After all that's exactly what people think these numbers mean, even though they most certainly don't.

Re: Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

#94

Post by BoredPositron »

throwup238 wrote: post #78
epolanski wrote: post #39

Earlier quoted context omitted.

1) Even if the max had hiccups, plenty of them, it is an absolutely safe airplane by any measure. 2) Your fleet may mostly be formed by Boeing airplanes, having all of those move to Airbus airplanes is also a safety issue. Pilots have to re-learn and even forget things they accrued and evolved to react instantly for decades. At some point you need to weigh the odds of increasing human error vs relatively safer Airbus…

> 1) Even if the max had hiccups, plenty of them, it is an absolutely safe airplane by any measure. Except fatalities.

"Some of you might die but that's a sacrifice I am willing to take." - some Boeing suit

Re: Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

#95

Post by krisoft »

CoastalCoder wrote: post #30
Havoc wrote: post #18

Thing is this could just keep going. There’s no telling how many bad apples Boeing put out there

If it's a software issue, I'd think owners would be pretty clear on its status on each plane. But for physical defects, yeah that's scary.

> If it's a software issue, I'd think owners would be pretty clear on its status on each plane.

That assume that it is a known software issue. If it is an issue with some unknown triggering factors how would they be clear on its status?

Re: Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

#96

Post by qwertox »

throw0101d wrote: post #37

Four minute video illustrating a dutch roll: * https://www.youtube.com/watch?v=9Gt-IcCBiQ4 Longer 15m video from Mentour Pilot with some more details: * https://www.youtube.com/watch?v=z2J_LUDWioA&t=1m

First video is very good for a clear explanation, second one to get a bit more comments from someone who knows.

Re: Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

#97

Post by FabHK »

jader201 wrote: post #87
tjpnz wrote: post #20

Earlier quoted context omitted.

Here's a video demonstrating it: https://youtu.be/Zmjam1evDD4

I feel like “roll” is a bad word for what’s happening here. In my brain, when I hear “roll”, I’m thinking a 360 degree rotation in either the vertical or horizontal axis (or both). This is far from that (even in the real life footage linked in the sibling comments). This is more like a “Dutch wobble” or “tilt”. But I’m not an aviator, so what do I know.

What you describe might be called a loop. In aviation, “roll” describes any rotation (not necessarily full 360) around the longitudinal axis, as “yaw” around the vertical and “pitch” around the lateral axis.

ETA: 360 degrees pitch is a looping, 360 degrees roll is a aileron roll or slow roll, a 360 degrees roll and pitch is a barrel roll, and 360 degrees yaw is “a 360”, ie a full circle turn.

Re: Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

#98

Post by kcplate »

cwillu wrote: post #88
kcplate wrote: post #68

Earlier quoted context omitted.

Uh yes, they were being sarcastic. Once again…the humorless HN strikes. Sheesh.

If the joke was worth making, the joke was worth suffering the downvotes. Have some courage in your convictions, and most importantly: don't whine about it.

My courage is strong, I’m willing to support a downvoted comment with another comment or two that I know will be downvoted to hell too…just to hold a mirror up to the humorless folk on here.

Re: Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

#99

Post by ragebol »

AnimalMuppet wrote: post #85
ragebol wrote: post #75

Earlier quoted context omitted.

Maybe the ice skaters took it from ships, also an old Dutch tradition I suppose.

I'm not sure if this is relevant, but: I have read that back in the day (1500s-1700s), the Dutch built flat-bottomed boats that could carry a lot, and the English built round-bottomed boats that handled better in the ocean. Maybe the way a Dutch boat handled in heavier seas is the origin of the term?

Sounds plausible, your guess is as good as mine

Re: Southwest Airlines Boeing 737-8 Max Experienced Dutch Roll

#100

Post by ToucanLoucan »

marcus0x62 wrote: post #24

Years ago, my father in law ( a heavy jet mechanic) got sent to China for two months as part of a team to diagnose and fix a recurring dutch roll complaint on a particular airframe. This was for a A300-series flown by a large freight carrier. The local mechanics couldn’t figure it out, so this team was assembled from the mechanics at headquarters to fix the plane. They inspected the plane and found no damage. They ha…

> and really high quality counterfeit Fluke multimeters he got from the local market, though.

I got one of those years ago. Wouldn't trust it on any industrial shit but I've used it for residential electrical tinkering (plus smaller projects) for years, works great and has never had a single issue.

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