I don't understand why there's not something that just allows the pilots to completely turn off all autopilot systems without also turning off hydraulic supports? It seems like if they turn off autopilot it makes the steering become not powered or something?
Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS
151–160 of 341 posts
Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS
#152Earlier quoted context omitted.
I think we're talking past each other. MCAS is stability control which a lot of planes have and is allowable to pass certifications. However MCAS also makes the MAX behave like the older design which specifically led to the gap in training and controls over the system. If they just had stability control but without the emulation of behavior then there would be new training and certification, which is something they w…
There is no other modern airliner with a software bodge for static stability. No, Airbuses are not comparable (Airbus FBW control laws are _not_ for stability control) and they are (to the best of my knowledge) positively stable throughout the flight envelope in direct law. Emulation is incidental. Redesigning the 737 with FBW is not something that Boeing would've considered, even for a moment.
It was certified though so it seems we agree that the stability control system was not robust enough and the training for it was not sufficient enough?
Is the cause for that just oversight then? And further exacerbated by similar behavior leading to even less training requirements?
Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS
#153Earlier quoted context omitted.
it’s not just pr reasons. they tried to hot patch this airplane design with software, and now they are hot patching that fix. it seems it is a fundamentally flawed design that they tried to hide and get away with rather than doing the right thing. i know i don’t want to fly on a 737 max ever, and this whole ordeal with boeing and the faa has made me less confident in the airline industry as a whole. your parenthetica…
The fix taking a while to get right is not evidence for "fundamentally flawed". You have a strange idea about how to assess risk. It's like faults are somehow contagious.
The notion that you can fix an aerodynamic stability problem in software by making a software program mimic the flight characteristics of an older plane is fundamentally flawed. And the notion that we can just patch the system later if it turns out you did it wrong is dangerous. You're betting with human lives that this time you've got it right.
Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS
#154Wait, what? Reading this is turns out that flipping both switches on the centre panel not only deactivates MCAS, but also deactivates the thumb switch on the control wheel that the pilots routinely use to change the elevator trim. So, MCAS trims the plan to a dangerous attitude, then when pilots follow Boeing's SOP to disable, they lose the ability to re-trim the way they have done it a million times before? I can se…
Yes, exactly. The MAX "stab trim cutout" simply disabled the trim motor altogether. Everything you describe appears to have happened in the Ethiopian flight report. A 737 pilot also tried to run the same flight in simulator and had his arms wrapped around the control column trying to hold level while the copilot failed to move the trim wheel.
Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS
#155What is the endgame now for 737 MAX planes? Every airline using them has had several weeks to totally reorganize to deal with these huge missing parts of their fleets. Boeing keeps talking about fixing them and putting them back in the air, but I dunno. At this point, it should be agreed the fundamental design flaws are serious, and Boeing should have simply made a brand new plane, with much more modern controls and…
I think the 737 MAX should be properly re-certified as a new airplane once the "fixes" are implemented. The whole idea that you can significantly alter an existing airplane by mounting larger engines more forward, add new automatic systems, and still pretend that it's the same airplane, is flawed.
Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS
#156Earlier quoted context omitted.
You're putting the safety record into chauvinist context, to be exact. An AoA failure is sufficiently rare for it to have only occured in a couple of occasions in - shockingly - only a couple of countries.
Okay, I probably should have calculated the number of successful flights to avoid this. But, nowhere did I say any country is better than any other. That's your inference.
I can help with that -- the MAX is suffering hull losses per flight completed at a rate about 100x that of comparable planes like the A320. Totally off the charts.
Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS
#157What is the endgame now for 737 MAX planes? Every airline using them has had several weeks to totally reorganize to deal with these huge missing parts of their fleets. Boeing keeps talking about fixing them and putting them back in the air, but I dunno. At this point, it should be agreed the fundamental design flaws are serious, and Boeing should have simply made a brand new plane, with much more modern controls and…
There's no fundamental design flaw, the aircraft is sound. The problem came from using software systems to artificially make the plane behave like older designs to avoid entirely new training and certifications. Even that would've been acceptable and similar systems are already in use in other planes but it was the inadequate info, redundancy, warnings and controls to disable the system that created the problem. It's…
> There's no fundamental design flaw, the aircraft is sound.
From what I have read, the new aircraft design had a habit of raising it's nose when engine power was applied, which put the plane into a situation where it might stall.
The MCAS was added to automatically detect this behaviour and stop the nose lifting.
So basically, without the MCAS, under certain scenarios the plane had a tendency to want to stall.
That does suggest the aerodynamic design of the plane is less than ideal and this could even be considered a design fault.
Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS
#158Earlier quoted context omitted.
> The engine mounting certainly does not make the plane unsafe. I don't think this is a very...'precise' statement. what is "safe" in the context of aviation? If you had no MCAS, then this plane has a very bad propensity to stall . I hope we can both agree that's an unsafe airplane. You can't just say "don't do that [pull up too much] and then you're fine". The aircraft "wants" to pitch up too high and stall, which p…
No, it did not “have a bad propensity to stall”. That’s a very imprecise statement in the first place but if you take it to mean, it would try to stall during normal flight conditions, it’s definitely false. Airbus aircraft are “safe” despite the fact that dual conflicting pilot input is averaged without stick feedback (see the Airfrance flight from Brazil). If electronics being used to fly the aircraft upsets you, y…
if it didn't have a propensity to stall, why did they add the MCAS system?
Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS
#159What is the endgame now for 737 MAX planes? Every airline using them has had several weeks to totally reorganize to deal with these huge missing parts of their fleets. Boeing keeps talking about fixing them and putting them back in the air, but I dunno. At this point, it should be agreed the fundamental design flaws are serious, and Boeing should have simply made a brand new plane, with much more modern controls and…
I think the 737 MAX should be properly re-certified as a new airplane once the "fixes" are implemented. The whole idea that you can significantly alter an existing airplane by mounting larger engines more forward, add new automatic systems, and still pretend that it's the same airplane, is flawed.
Could not agree more. This is the real “fix” once the plane is rendered safe ... if the regulators or Boeing can ever be trusted about thus airframe again.
Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS
#160Earlier quoted context omitted.
> The bugs will be addressed and they'll still fly. The engines are mounted incorrectly, so much so that Boeing believed pilots need the assistance of MCAS on take-off now. The bug isn't with its algorithms, rather the need for MCAS to begin with. They can't "address" it. That's why I'll be very careful not to ever book a flight on a 737 Max, probably easier to simply stick to Airbus-only airlines: Jetblue, Alaska/Vi…
> The engines are mounted incorrectly, so much so that Boeing believed pilots need the assistance of MCAS on take-off now. This overstates the issue. The engine mounting changes the flight characteristics enough that the MAX 8 needs to be flown differently in certain corners of the flight envelope. The MCAS was added to avoid having to re-train pilots or trigger a new type certification. The engine mounting certainly…
The engine mounting certainly does not make the plane unsafe.
The engine position exacerbates a problem already plaguing the 737 since the Classic. I think you're understating the problem quite a bit here.