Why does the title mentions "EU's Biggest Economies", when it is affecting all the european union ? It is a very confusing title.
The original title was : E.U. Suspends All Operations of Boeing Max Model That Crashed
E.U.’s Biggest Economies Ban Boeing Max 8 Jets
321–330 of 365 posts
Re: E.U.’s Biggest Economies Ban Boeing Max 8 Jets
#322Earlier quoted context omitted.
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 gene…
If I have an upcoming flight on a MAX 8, can I sufficiently compensate for any increased risk by taking the train to the airport instead of a 25km Uber drive?
Given the uncertainty about p(crash) that I mention, then to satisfy confidence limits, you should wear a styrofoam helmet for the full duration of your trip. And post a photo.
Re: E.U.’s Biggest Economies Ban Boeing Max 8 Jets
#323Earlier quoted context omitted.
>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.
Obviously stability has to be achieved through fly by wire tech. Doing it through natural aerodynamic stability is a waste of resources of insane proportions as such airframes induce more drag and burn more fuel. If this sounds too scary for people in a forum of software developers it only puts a shame on our profession, from ourselves.
The software itself isn't necessarily the issue, though- it's also all the sensors and actuators involved.
Suppose, for instance, that an aircraft needs more yaw stability.
There's all sorts of design choices that could be made, but consider either A: a larger vertical stabilizer or B: automatic application of the rudder to damp oscillations.
The vertical stabilizer here is essentially a bit of metal. We know very, very well what can go wrong with bits of metal. Fatigue, corrosion, manufacturing defects, bad repairs... But, in 2019, we've pretty much figured out the failure modes of big bits of metal on an aircraft, and we generally know how to prevent and/or minimize them.
Now, the dynamic stabilization approach. We'll need gyroscope data (from the IRS, probably), a software model of flight dynamics (which almost certainly already exists and is running), and possibly faster servo valves for the rudder actuator.
This can work! We can formally verify that the control system we've created damps oscillations throughout all normal flight regimes. The gyroscopes are already redundant and well-tested. And you might not even need the faster servos.
Problem is, now avionics failures are even scarier. Will the stabilization here still operate when you get dropped into secondary mode? Probably not- so now, in unexpected situations, pilots need to keep in the back of their minds that yaw oscillations are more possible, that they may need to damp them manually, etc, etc.
Now you throw in some extra factors- turbulence, IMC (which would probably make detecting those oscillations manually that much more stressful), and trying to solve whatever problem dropped you into secondary mode in the first place... and you have something a bit concerning!
A bit of metal won't do that to you. We can make much better estimates of a bit of metal's reliability, and its failures are also less correlated- they aren't much more likely to crop up when you already have another problem.
Re: E.U.’s Biggest Economies Ban Boeing Max 8 Jets
#324Earlier quoted context omitted.
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…
How is the FAA responsible for crashes outside of its jurisdiction? There haven’t been any 737 Max 8 crashes in the US. I can’t speak for Ethiopian, but Lion Air and Indonesia in general have a pretty bad safety record. Lion Air was removed from the EU safety blacklist in 2016. In 2013 another Lion Air 737 (not the Max 8) crashed into the ocean near Bali. Lion Air has had pilot test positive for crystal meth (2012).…
> How is the FAA responsible for crashes outside of its jurisdiction?
They have jurisdiction over the type certification as the responsible regulatory body for the nation of origin of the airframe.
Re: E.U.’s Biggest Economies Ban Boeing Max 8 Jets
#325Earlier quoted context omitted.
No, but the pilots will hear/see the trim wheel moving.
Inattention to autopilot modes has killed before. So much focus is put on pilots recognizing and confirming flight mode annunciator mode changes (such as change of autopilot or autothrottle state) has been put into place to stop that kind of accident. The lack of feedback from the MCAS system is probably the killer here. How am I supposed to know that MCAS is operating, and how do I know when to hit trim cutoff switc…
The Lion Air pilots were not even aware of the existence of the MCAS system, because Boeing at the time did not include any information about it in its manuals.
The behavior would be similar to runaway stabilizers, though, for which B737 pilots have memory items to perform (turn off the trim). This would have solved that problem. However, several other warnings and alerts, like stick shaker, might have been going off at the same time, making the situation chaotic and problems hard to diagnose.
Re: E.U.’s Biggest Economies Ban Boeing Max 8 Jets
#326Earlier quoted context omitted.
Traditionally the fly-by-wire systems have at least 3 AoA sensors, which each "vote" on the output value. That way, if you have one faulty sensor, it gets outvoted. The MCAS system in the new 737-MAX's only have 2 AoA sensors, which means a single faulty sensor can cause bad things to happen.
MCAS is not a fly-by-wire system. Pages and pages of speculation by arm-chair aircraft designers going on. So depressing.
I understand it's not a fly by wire system.
I was comparing it to the other common use of AoA sensors.
Do you have anything real to add here other than "I am Very Smart and everyone else is not"?
For example, whether it is a fly by wire system or not does not change anything about what i said about the sensors.
Re: E.U.’s Biggest Economies Ban Boeing Max 8 Jets
#327Earlier quoted context omitted.
Yes it would. There are backup systems to keep things working even with both engines dry (ram air turbine etc). In fact, if you really want to stretch our a glide, all those automated systems are probably a good things. They will keep the aircraft more perfectly trimmed for a glide than the pilots ever could by hand. https://en.wikipedia.org/wiki/Ram_air_turbine
And in case of the electrical system being down how do you control the flight when you have fly by wire controls?
>>And in case of the electrical system being down
That is what the RAT is for, alternative electrical power. If the entire electrical system is down, ie electrons no longer flow anywhere anyhow, then everyone is doomed. But that is up there with the tail falling off. The are no backups for the wings/tail either.
Re: E.U.’s Biggest Economies Ban Boeing Max 8 Jets
#328Earlier quoted context omitted.
Pilots have been pushing back hard on the narrative that this was simply pilot error. The crux is that safety agencies never mandated training on these new systems, and new procedures weren't created with them in mind. Worse still procedures from older models of the same aircraft (such as automatic overriding of auto-trim) were removed without re-training on that either. Lion Air had to repair the AOA sensor multiple…
I recall reading on HN that a second AOA sensor was an option.
If the AOA sensor is safety critical they need three, rather than two.
The inherent problem with two is if one is feeding false data, you don't know which one, whereas if you have three (or more; but an odd number) you can cross-check the data and drop the faulty one.
It is a very common strategy already for commercial aviation and is called "voting logic."
> A more reliable form of voting logic involves an odd number of three devices or more. All perform identical functions and the outputs are compared by the voting logic. The voting logic establishes a majority when there is a disagreement, and the majority will act to deactivate the output from other device(s) that disagree. A single fault will not interrupt normal operation. This technique is used with avionics systems, such as those responsible for operation of the Space Shuttle.
But the real crux here is: Is the AOA sensor safety critical or not? If it can fail-safe then they can likely continue as it is currently designed. But if its failure state can cause an aircraft crash, then it becomes a safety critical component.
Re: E.U.’s Biggest Economies Ban Boeing Max 8 Jets
#329The black box has been recovered. The data is probably being recovered as we pontificate. Within the next 48-72 hours I expect someone will know definitively if the MCAS system was even active, and if trim was a factor in this crash. Given that this significant data point is hours or just a couple days away, isn’t it prudent to get the data before grounding the fleet? If the jet had been brought down intentionally, s…
While I see your point, no, I think it's prudent to ground the fleet immediately.
Two of the same plane have crashed in 5 months and 346 people are dead.
Re: E.U.’s Biggest Economies Ban Boeing Max 8 Jets
#330Earlier quoted context omitted.
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…
How is the FAA responsible for crashes outside of its jurisdiction? There haven’t been any 737 Max 8 crashes in the US. I can’t speak for Ethiopian, but Lion Air and Indonesia in general have a pretty bad safety record. Lion Air was removed from the EU safety blacklist in 2016. In 2013 another Lion Air 737 (not the Max 8) crashed into the ocean near Bali. Lion Air has had pilot test positive for crystal meth (2012).…
Even if all this speculation of yours is true, it's still the FAA's and Boeing's problem.
These supposedly awful third world pilots and aircraft engineers have somehow been managing to fly earlier models of the 737 for decades, but when they upgrade to the MAX variant somehow two of them crash in quick succession?
That either indicates that these two events are freak accidents, or that the MAX shouldn't have the same type rating, the latter of which is on the FAA and Boeing.