Would you still fly with Boeing Max after all this? I understand that the "issue" can be fixed with software but it looks like a hardware/design issue in the first place.
If your highest priority is safety the software should be used only when the hardware fails not to support a flawed design.
Boeing MAX production cut signals long grounding
101–110 of 164 posts
Re: Boeing MAX production cut signals long grounding
#102Earlier quoted context omitted.
I think that would be unfortunate. I don't think it should die over this. The issues are eminently fixable. But a number of executives may have to exit Boeing, and the FAA, in order for the plane to not die, and all the issues must be fixed of course.
> The issues are eminently fixable Not really. I am no expert, that is why I no longer trust FAA/Boeing telling me it is safe any more, at least in this particular case. As a passenger, I would avoid buying tickets from this plane even it means more cost
What about it isn't fixable? Redundant (and thus more reliable) AOA sensors + a less aggressive MCAS system that at maximum displacement can't override the yoke would be more than enough of a fix for me.
Re: Boeing MAX production cut signals long grounding
#103Earlier quoted context omitted.
You can't compensate because you don't know which one is wrong. However you can make MCAS inactive whenever the two sensors are disagreeing with each other.
With the current two sensor setup, that is true. This is why the parent poster is arguing for 3 sensors (and the real reason for tripling). If not all sensors agree but 2/3 do, it is more probable that the two sensors are correct than the 1 sensor disagreeing.
Right, but the MCAS system as it was implemented during those two crashes did not disable itself when the two sensors disagreed. It could have, but didn't. Boeing is apparently changing that, and I believe that change to be sufficient.
MCAS being automatically disabled when the sensors agree but leaving the pilots with electronic trim control seems like a perfectly adequate solution. The MCAS system was never even necessary for flight, it was only necessary for certification. In the situations where it's meant to be active, which are a limited subset of all high angle of attack scenarios, it's fine system to have if it's working correctly. But it should never be active outside of that limited set of scenarios. It should never be active when both angle of attack sensors aren't indicating a high angle of attack within a reasonable distance of each other.
Frankly, if two sensors are indicating a high angle of attack and one is not, it's probably still sensible to disable MCAS. I don't have any of the real numbers, but the chance of a 737 being in a low speed high angle of attack scenario is low in the first place, possibly sufficiently low that "two sensors being wrong and the aircraft being in level flight" might be more likely than "aircraft is near stall and one sensor is wrong."
To know for sure we'd need at least the hard data on what modes of failure these sensors have, how likely any of those modes is to occur and what the expected readouts from those failure modes are, and how likely a 737 is to encounter a low speed stall scenario. We, or at least I, don't have any of that. But my gut says that two sensors are sufficient iff the MCAS system is only active when they agree.
Furthermore, the chance of two sensors being wrong actually goes up if you have three sensors, rather than two. Correct me if I'm wrong, stats was never my strong point, but it seems to me like the cumulative binomial distribution is relevant here:
#lang racket
(require math/number-theory)
(define (general-binomial p k n)
(* (binomial n k)
(expt p k)
(expt (- 1 p)
(- n k))))
(define (cumulative-general-binomial p k1 k2 n)
(apply +
(map
(λ (k) (general-binomial p k n))
(range k1 (add1 k2)))))
> (cumulative-general-binomial .01 1 1 1)
0.01
> (cumulative-general-binomial .01 2 3 3)
0.00029800000000000003
> (cumulative-general-binomial .01 2 2 2)
0.0001
(In other words, two broken sensors voting out a third working sensor is more likely than two out of two sensors being broken.)
Re: Boeing MAX production cut signals long grounding
#104Earlier quoted context omitted.
The fact that my comment is ironic...
Then you don't understand irony. Which is itself ironic. I was using the word in this sense: "Irony: a literary technique, originally used in Greek tragedy, by which the full significance of a character's words or actions are clear to the audience or reader although unknown to the character."
This isn't a story, and I am not a character. If that's what you were using it like, you are wrong. It'd make at least some sense if you incorrectly meant "irony" in the sense that fucking with the FAA, which I said was bad, is how the MAX was made so poorly.
Your fake choice of definition is even worse than what you actually meant.
Re: Boeing MAX production cut signals long grounding
#105Would you still fly with Boeing Max after all this? I understand that the "issue" can be fixed with software but it looks like a hardware/design issue in the first place. If your highest priority is safety the software should be used only when the hardware fails not to support a flawed design.
I would be perfectly comfortable flying on the 737 Max right now even without the software fixes.
Re: Boeing MAX production cut signals long grounding
#106Would you still fly with Boeing Max after all this? I understand that the "issue" can be fixed with software but it looks like a hardware/design issue in the first place. If your highest priority is safety the software should be used only when the hardware fails not to support a flawed design.
Sure, assuming it's just MCAS. The B737 program has had previous problems most notably uncommanded rudder movement that caused two US crashes in the 1990s with loss of all on board. [1]
From what's visible so far in the investigations Boeing (a) botched the MCAS implementation and (b) failed to train pilots on differences between the Max and previous models. Cure those two and the problem seems to be solved.
Re: Boeing MAX production cut signals long grounding
#107Earlier quoted context omitted.
> I also doubt customers will really vote with their feet Agreed. As the article points out: "Passengers eventually returned to flying the 787 and to other airplanes that were grounded: the McDonnell Douglas DC-10, the Douglas DC-6, the Lockheed Constellation and even the de Havilland Comet."
I'm not sure the DC-10 is a great example. It was grounded in 1979 and discontinued in 1983 after airlines stopped ordering it. The company never recovered and died a long and slow death until Boeing scooped them up.
Neither is the Lockheed Electra (one would guess that the author means that airplane instead of the Constellation). Airlines cancelled their orders and Lockheed had to end production of the model early, leading to very substantial losses for the company.
Re: Boeing MAX production cut signals long grounding
#108Earlier quoted context omitted.
With the current two sensor setup, that is true. This is why the parent poster is arguing for 3 sensors (and the real reason for tripling). If not all sensors agree but 2/3 do, it is more probable that the two sensors are correct than the 1 sensor disagreeing.
Right, but the MCAS system as it was implemented during those two crashes did not disable itself when the two sensors disagreed. It could have, but didn't. Boeing is apparently changing that, and I believe that change to be sufficient. MCAS being automatically disabled when the sensors agree but leaving the pilots with electronic trim control seems like a perfectly adequate solution. The MCAS system was never even ne…
I think your maths is sound but the question is what are the odds that multiple sensors fail on the same flight (and I don't know the answer)?
Because as soon as one sensor fails that aircraft will go in for maintenance.
Re: Boeing MAX production cut signals long grounding
#109Would you still fly with Boeing Max after all this? I understand that the "issue" can be fixed with software but it looks like a hardware/design issue in the first place. If your highest priority is safety the software should be used only when the hardware fails not to support a flawed design.
I would be perfectly comfortable flying on the 737 Max right now even without the software fixes.
How is that? Even if its nose goes down after take off? That's something for sure.
Re: Boeing MAX production cut signals long grounding
#110Earlier quoted context omitted.
> The issues are eminently fixable Not really. I am no expert, that is why I no longer trust FAA/Boeing telling me it is safe any more, at least in this particular case. As a passenger, I would avoid buying tickets from this plane even it means more cost
What about it isn't fixable? Redundant (and thus more reliable) AOA sensors + a less aggressive MCAS system that at maximum displacement can't override the yoke would be more than enough of a fix for me.
Not GP but I'm mainly wondering about the likelihood of departure stalls with this design.