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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

#211

Not the incident from the article, but this footage of some other aircraft doing a Dutch Roll is illustrative: https://www.youtube.com/watch?v=2tgfkGiHhxs

[flagged]

Airplane in the video is a Russian design, and the flight appears to have been done for demonstration.

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

#213

Earlier quoted context omitted.

The post I was responding to was speaking precisely about "the least safe Boeing plane in service." The fact that airplanes are, trip for trip, much safer than planes is something I did not appreciate at the time when making my post. I expected most planes to be safer than vehicles, but Boeings falling well below average. The fact that vehicles are substantially safer than any plane, trip for trip, is far beyond what…

> You're having a failure where you keep misreading something the same way. And you are having a failure where you are not quoting what you think I'm misreading. Look at the table. First column labeled "ACCIDENT TYPE". Second row first column "All accident rate (accidents per one million flights)". Last column labeled "5-YEAR AVERAGE (2019-2023)" The data in second row last column "1.19 (1 accident every 0.88 million…

Ahhh!!! I see how you're reading it, and yeah - I think the mistake is much more on them than you. The parenthesis are not describing the value before them, but indicating what is IN the parenthesis! I'm the sort that ignores infographics and goes straight to the text, and it's much clearer there. Check out the report highlights:

---

The all accident rate was 0.80 per million sectors in 2023 (one accident for every 1.26 million flights), an improvement from 1.30 in 2022 and the lowest rate in over a decade. This rate outperformed the five-year (2019-2023) rolling average of 1.19 (an average one accident for every 880,293 flights).

---

So in the table their "All accident rate (accidents per one million flights)" row is giving you two different pieces of the data. The first is accident rate (which is per million sectors) and then in the parenthesis is the accidents per million flights. And actually even that's wrong, since they actually give you flights per accident -- whoever put that table together clearly was not big on the whole accuracy thing.

So when you see "1.19 (1 accident every 0.88 million flights)" that means the rate per million sectors is 1.19, and the rate per million flights is 1/0.88 = 1.14.

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

#214

Earlier quoted context omitted.

Dutch Roll is a coupling of yawing and rolling dynamic modes, and is a product of the aircraft's aerodynamics. If the aircraft is disturbed off a steady-state path either by control input, changing winds, or turbulence, then it should return back to it's steady-state path with oscillations that quickly dampen. Dutch Roll is a phenomenon where these oscillations grow rather than dampen as a result of out-of-phase yaw…

> This is different than the aircraft just being batted around by turbulence. Does it actually look different or is it just a different cause for similar movement patterns?

Just being batted around by turbulence looks different if you know what you're looking for (although what to look for might be only obvious when looking at accelerometer data). Again, Dutch Roll is a very specific phenomenon as a result of coupling between the roll and yaw dynamic modes. The risk of Dutch Roll is that these oscillations can grow even without further stimulus rather than just dampen out.

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

#215

This just isn’t Boeing’s decade.

Until the McDonnell Douglas management retires, Boeing will not recover. It's not a matter of an unlucky decade, it's a matter of replacing engineering with MBAing. It's just that the latency between cause and effect are long on the engineering side of this industry.

Those guys are top tier you have to admit— tank their company, get acquired, keep their jobs, eventually wrangle their way into managing their acquirer, tank the acquiring company… this is god tier MBAing.

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

#216

Earlier quoted context omitted.

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 b…

> like it hit a sudden pocket of turbulence at the apex of the turn I wonder if this could have been wind shear? Wind shear was deemed as the cause of the crash for Delta 191[0] on approach to DFW in the 1985. Lots of new equipment was installed after to detect wind shear. I wonder of MEX has that kind of equipment. [0] https://en.wikipedia.org/wiki/Delta_Air_Lines_Flight_191

Possibly, I don't think so. It happened right at the top of the bank and stopped as the plane began to ease out.

There were no weather issues no other incidents of turbulence or jostling around. It seemed as if the plane was having problems banking at that angle.

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

#217
post #194

Earlier quoted context omitted.

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 b…

I hope nobody got hurt (assume so, you may have told you otherwise). Is this something pilots get trained for how to cope with this type of incident? What happened to passengers (are they usually injured from things falling/flying around)? Boeing is getting some bad news these days, but multiple whistle-blowers in a row is the worst.

It wasn't that extreme, it was what I would consider a medium level of turbulence. I just realized my comment wasn't written correctly - the bank itself is what caused the issue, not that it just suddenly started banking unexpectedly. What was interesting was that it specifically started and stopped as it eased into and out of the turn.

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

#218
Looking at flightradar24, the only real upset I see is the turn over the southern Sierra Nevada range which is also ~55 minutes before arrival into OAK.

Wonder if mountain waves play any part in this incident? It's the only thing I can think of that could possibly generate a dutch roll without continuing flight stability issues. (They could have also turned on/off something like the yaw damper in the cockpit but that's not specifically called out int he report)

I can't imagine the standby PCU causing this incident unless there was some kind of electrical or pneumatic issue causing it to engage.

But 737 + PCU issues (yes, I know it's been redesigned) is never a good day.

Hopefully we'll get a NTSB report on this one.

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

#219

Earlier quoted context omitted.

Eek… I’d never want to fly a plane that’s beneath me. I’d prefer it to be at the same altitude.

Technically any plane should be beneath you. Also above you, but beneath you too.

Mitch Hedburg? Is that you?

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

#220
post #98
post #88

Earlier quoted context omitted.

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.

You do realise my comment was a joke right? In fact, I believe HN karma exists for the sole purpose of burning it on jokes.

I mean obviously they were being downvoted because it’s nothing to do with the Dutch, it’s just a fart fort.

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