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E.U.’s Biggest Economies Ban Boeing Max 8 Jets

nytimes.com

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Re: E.U.’s Biggest Economies Ban Boeing Max 8 Jets

#251

Post by dukoid »

ak217 wrote: post #32
paganel wrote: post #14

Earlier quoted context omitted.

It looks like Norwegian is already asking its 737 Max flights to return to their departing airports, at least according to this recent screenshot I found on reddit [1] [1] https://i.redd.it/6gtecemacpl21.png

Wow. This is pretty ridiculous considering all three of these planes seem to have been closer to their destination than the origin, making it safer to just finish the planned flight.

They got bitten by this recently: https://matadornetwork.com/read/norwegian-air-emergency-land...

(emergency landing in Iran, can't get parts there because of sanctions)

Re: E.U.’s Biggest Economies Ban Boeing Max 8 Jets

#252

Post by zanmat0 »

AWildC182 wrote: post #219
sfilargi wrote: post #146

I urge people to read the discussion by pilots regarding the 737 MAX. https://www.airlinepilotforums.com/safety/120514-ethiopian-7... It all comes down to this: "There are far too many aerodynamic bandaids that are permitted to pass the current standards. Not just this particular airplane, but a whole bunch of airframes. If the basic aerodynamics won't pass without the pushers, pullers and now AOA induced changes to…

It's a bit more complicated than that even. The 737 was originally designed for a very different mission than it's being used for right now. If you find pictures of the original 737-200s they look very different from the MAX line of today. It was built in an era when it was assumed that 707 and soon after 747 class airliners would serve the hubs and then smaller 737s would serve the small regional airports. As such t…

>if you do as the pilots want and achieve very high aerodynamic stability through the air-frame instead of stability control systems (fly by wire essentially) it reduces the aerodynamic efficiency of the airliner

It's crazy to me that that would be an acceptable compromise.

Re: E.U.’s Biggest Economies Ban Boeing Max 8 Jets

#253

Post by erokar »

dukoid wrote: post #247
sfilargi wrote: post #146

I urge people to read the discussion by pilots regarding the 737 MAX. https://www.airlinepilotforums.com/safety/120514-ethiopian-7... It all comes down to this: "There are far too many aerodynamic bandaids that are permitted to pass the current standards. Not just this particular airplane, but a whole bunch of airframes. If the basic aerodynamics won't pass without the pushers, pullers and now AOA induced changes to…

When I see cockpit videos, the pilots tell each other what they do / run checklists together... Does the MCAS do the same, i.e. announce "stall risk detected, increasing stabilizer trim by 2.5 degree to xx degree"?

No, but the pilots will hear/see the trim wheel moving.

Re: E.U.’s Biggest Economies Ban Boeing Max 8 Jets

#254

Post by cmurf »

I found both of these relevant:

https://leehamnews.com/2018/11/07/boeing-issues-737-operatio...

https://leehamnews.com/2018/11/14/boeings-automatic-trim-for...

Either not widely reported or lost in other confusion, that I find important about Lion Air, from the first article:

Indonesian crash investigators have said the 737 MAX involved in the crash has flown with unreliable airspeed information in the last four flights.

That very well could make identification and corrective action for the problem more difficult. And then, there is in fact a different behavior in the MAX with MCAS in normal operation that pilots weren't made aware of, and results in this central question in the 2nd article:

How should [pilots] know that pulling on the Yoke didn’t stop the trim?

In previous 737's, pulling on the yoke does stop trim, but that's contrary to the point of MCAS which is why it has different behavior, but it's a behavior pilots aren't aware of and haven't trained for; and both Boeing and the FAA have been saying 737's all have the same behaviors and flight characteristics. And that becoming clearly not the case is really pissing everyone off.

Re: E.U.’s Biggest Economies Ban Boeing Max 8 Jets

#255

Post by nabla9 »

anoncoward111 wrote: post #119
eric_b wrote: post #109

At the gym today, on all the TVs, the media talking heads were crucifying the FAA for being "unsafe" or playing fast and loose with passenger safety (for not grounding the planes). I've always held the FAA in high regard, and think they do a good job. Are they really being negligent here? Or is the media just looking for something to spark outrage? Can anyone with more specific knowledge of aircraft safety weigh in?

Two crashes in 6 months and there's only 350 planes in existence is a pretty bad safety record that is probably on par with Tupolev. The US can tacitly blame "third world" pilots all they want, but with 300 people dead already, I think it's important for the FAA and Boeing to say exactly what is going on, especially since the planes are in use in the USA. There is a debate over if the plane's hardware, software, or p…

Both crashes happened soon after takeoff (6 and 13 minutes) and Boeing seems to think that they know where the error is (stall in high angle-of-attack) and have a fix in pipeline. FAA is taking calculated risk.

Re: E.U.’s Biggest Economies Ban Boeing Max 8 Jets

#256

Post by Scoundreller »

mrdodge wrote: post #152
cal5k wrote: post #147

Earlier quoted context omitted.

The 777 is the second-safest aircraft in the world, next to the Airbus A340. The 787 is on track to demonstrate a similar safety record (in terms of fatal incidents). So overall, they seem to be quite good.

Those were produced pre-FAANG, Boeing probably paid comparatively better then. Do the smartest software engineers flock to Boeing in 2019? I think the relatively low pay and status of software engineers outside of the Bay Area is a huge risk to society. We are going to start seeing it show up in interesting places.

And increasing demand from the security-industrial complex that also does military/classified work.

Boeing can’t H1-B its way out of underpaying like other engineer employers.

Re: E.U.’s Biggest Economies Ban Boeing Max 8 Jets

#257

Post by riazrizvi »

anoncoward111 wrote: post #119
eric_b wrote: post #109

At the gym today, on all the TVs, the media talking heads were crucifying the FAA for being "unsafe" or playing fast and loose with passenger safety (for not grounding the planes). I've always held the FAA in high regard, and think they do a good job. Are they really being negligent here? Or is the media just looking for something to spark outrage? Can anyone with more specific knowledge of aircraft safety weigh in?

Two crashes in 6 months and there's only 350 planes in existence is a pretty bad safety record that is probably on par with Tupolev. The US can tacitly blame "third world" pilots all they want, but with 300 people dead already, I think it's important for the FAA and Boeing to say exactly what is going on, especially since the planes are in use in the USA. There is a debate over if the plane's hardware, software, or p…

The Boeing Max 8 entered service in May 2017. Assuming a linear deployment rate, the 350 planes in service have seen an average life of 10 months. Assume 4 flights/day, that's 420,000 flights so far. 2 have gone down. A best estimate of the likelihood that a plane goes down (MLE), p = X/n = 2/420,000 = 1/210,000 ~ Binomial(n=420,000, p=P(crash)). According to the Economist [1] the likelihood your plane goes down generally is 1/5,000,000. So based on the fact that the plane crashes had similar characteristics, the Boeing Max 8 is 25X more dangerous than a regular plane. 25X is the difference between surviving a commute on a bicycle vs a car [2].

[1 https://www.economist.com/gulliver/2015/01/29/a-crash-course...].

[2 https://www.riskcomm.com/visualaids/riskscale/datasources.ph...].

EDIT: The Economist source that estimates a plane's p(crash) is questionable, for a passenger plane. If anyone wants to dig into this further, I found this source too: http://www.baaa-acro.com/crash-archives

Re: E.U.’s Biggest Economies Ban Boeing Max 8 Jets

#258

Post by Gibbon1 »

dahdum wrote: post #128
Reason077 wrote: post #110

Earlier quoted context omitted.

One thing to note is that both American and Southwest's 737 Max aircraft are configured differently to those flown by most other operators, with regards to the display of AOA indicators and the "AOA DISAGREE" warning light. These features are optional and the fact that they are not present on Lion Air's aircraft may have contributed to that crash. https://theaircurrent.com/aviation-safety/southwest-airlines...

That would mean Southwest strongly believes the lack of "AOA DISAGREE" caused the crashes, so they are safe to continue flying their fleet. If so, they should come out and say it. Right now, 737 Max Fleet is the deadliest plane per mile that is in the air [1], by a wide margin. Maybe it's an anomaly and the rate is much lower, but by the same reasoning, it could be worse. I'm not flying on one, and my opinion of Sout…

One thing that I keep rolling over in my head is right now it wouldn't appear that the pilots should have been been able to fly without instruments when they crashed. And both crashed apparently due to the pilots being unable to control pitch.

Two lost aircraft. Both new. Both with the same symptoms. Under conditions you would not expect to lose an aircraft.

That's a really really bad sign.

Re: E.U.’s Biggest Economies Ban Boeing Max 8 Jets

#259

Post by DuskStar »

kharms wrote: post #189
oppositelock wrote: post #137

Earlier quoted context omitted.

The FAA and Boeing need to investigate this, but you can't make such statistical inferences, since you simply don't have enough data points. There could be no more crashes for the next few years with those 350 planes. The FAA and NTSB are very good at what they do, one of the very few examples of government services that work well together with industry, give them some time.

We have some idea of a crash rate for safe airplanes. Something like: P(Crash|Miles Flow & Hull Age) If we assume this airplane is safe, we can apply that probability to it and then ask P(2 Crashes|N Miles & 350 New Planes). You would then have a probability for this just being bad luck, and compare that against your prior that this is a safe plane. I haven’t done the math, but my gut says it would point to grounding…

Might also be worth considering P(2 Crashes | N Miles across 350 planes where at least one operator has incompetent maintenance), because that might not be all that different from P(1 crash | N Miles across 350 planes where all operators properly maintain their planes)

Look at things like Alaska Airlines Flight 261 [0] - safe airframe, deficient maintenance, plane loses all pitch control and impacts ocean. Yes, this still means that Boeing needs to improve things - single points of failures are never OK on a plane - but it also doesn't (IMO) mean the plane is fundamentally unsafe without those fixes.

0: https://en.wikipedia.org/wiki/Alaska_Airlines_Flight_261

Re: E.U.’s Biggest Economies Ban Boeing Max 8 Jets

#260

Post by bjourne »

kharms wrote: post #189
oppositelock wrote: post #137

Earlier quoted context omitted.

The FAA and Boeing need to investigate this, but you can't make such statistical inferences, since you simply don't have enough data points. There could be no more crashes for the next few years with those 350 planes. The FAA and NTSB are very good at what they do, one of the very few examples of government services that work well together with industry, give them some time.

We have some idea of a crash rate for safe airplanes. Something like: P(Crash|Miles Flow & Hull Age) If we assume this airplane is safe, we can apply that probability to it and then ask P(2 Crashes|N Miles & 350 New Planes). You would then have a probability for this just being bad luck, and compare that against your prior that this is a safe plane. I haven’t done the math, but my gut says it would point to grounding…

According to https://en.wikipedia.org/wiki/Aviation_safety#Evolution the fatal accidents per million flights were 0.39 in 2018.

The MAX8 fleet has been operational for about six months. Assuming 3 flights per day: 350 * 6 * 30 * 3 = 0.189 million flights.

To estimate the probability of two accidents, we can use a Poisson distribution with x = 2 and μ = 0.189 * 0.39 = 0.0737

P(x=2) = e^(-μ)μ^x / x! = 0.25%

I.e your gut feeling is correct (if my math is correct, that is). If one uses the estimate from a sibling comment of 1 crash in 11 million fights, the probability decreases further to 0.01% Actually the correct calculation is:

1 - P(x=0) - P(x=1) = 0.26%

since we are looking for the probability of there being more than one plane crash -- not just the probability of there being exactly two plane crashes.

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