Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

U.S. FAA proposes requiring key Boeing 737 MAX design changes

reuters.com

Post reply on HN
Print view View original

21–30 of 260 posts

Re: U.S. FAA proposes requiring key Boeing 737 MAX design changes

#21

Post by rootusrootus »

henryfjordan wrote: post #7
zaroth wrote: post #3

https://www.faa.gov/news/media/attachments/19_035n-R3-8-3-20... > "To address the unsafe condition, the FAA proposes to require four design changes: (1) installing updated flight control software (with new control laws) for the FCC operational program software (OPS), (2) installing updated MDS display processing computer (DPC) software to generate an AOA disagree alert, (3) revising certain AFM flightcrew operating p…

> disable MCAS for the remainder of the flight. My understanding is that the MCAS or something equivalent is necessary on the 737 MAX because the engines sit lower than they really should and the forward propulsion creates torque that raises the nose of the plane. Something needs to counteract that force. If the MCAS is disabled, is the pilot able to trim the airplane manually similar to how MCAS works? Or will they…

Basically all modern airliners with engines under the wing generate torque that tries to raise the nose of the plane. MCAS is to correct for nonintuitive behavior near the limit of the flight envelope when the wing is at a high angle of attack. Most flights never get anywhere near that, and disabling MCAS would not be noticeable.

Re: U.S. FAA proposes requiring key Boeing 737 MAX design changes

#22

Post by dharmab »

stevehawk wrote: post #20
Nacdor wrote: post #6

Given the option, would anyone choose to book a trip on one of these new Boeing aircraft rather than anything else? I know I wouldn't, my family wouldn't, and none of the friends or co-workers I've discussed this with would. Something tells me airlines are going to be making it even more difficult to determine which aircraft you'll be flying on when you book a ticket. As far as I know they're not required to tell you…

I would. I get it that Boeing messed up the first time, but this was always a failure that was preventable with proper pilot instruction and awareness. Even if they didn't fix the software I couldn't imagine a 737MAX pilot not being aware of this. People still drive Tesla's using autopilot and they drive head on into barriers on the highway or under trailers and decapitate people.

You have more confidence in the plane than the people who designed and built it.

https://www.nytimes.com/2020/01/09/business/boeing-737-messa...

Re: U.S. FAA proposes requiring key Boeing 737 MAX design changes

#23

Post by racnid »

onde2rock wrote: post #10

Hum, it doesn't seem like a lot. Maybe I missing something, but looks like a software update to make MCAS more robust. And if it bug, raise an alarm and flight-crew operating procedures should be (?) to deactivate MCAS and fly without ? Could pilots actually fly the plane without MCAS ? It must feels like an entirely different aircraft.

Yes, to my understanding the only issue a pilot would run into with MCAS disabled and neutral is decreasing control forces at high angles of attack. The FAA requires control forces to monotonically increase with angle. I say "only" but that probably makes for a very weird feeling airplane to fly; how dangerous that actually is for a trained pilot I can't answer for sure but my gut and experience tells me not very.

Re: U.S. FAA proposes requiring key Boeing 737 MAX design changes

#24

Post by karmelapple »

henryfjordan wrote: post #7
zaroth wrote: post #3

https://www.faa.gov/news/media/attachments/19_035n-R3-8-3-20... > "To address the unsafe condition, the FAA proposes to require four design changes: (1) installing updated flight control software (with new control laws) for the FCC operational program software (OPS), (2) installing updated MDS display processing computer (DPC) software to generate an AOA disagree alert, (3) revising certain AFM flightcrew operating p…

> disable MCAS for the remainder of the flight. My understanding is that the MCAS or something equivalent is necessary on the 737 MAX because the engines sit lower than they really should and the forward propulsion creates torque that raises the nose of the plane. Something needs to counteract that force. If the MCAS is disabled, is the pilot able to trim the airplane manually similar to how MCAS works? Or will they…

This might be oversimplification, but I'll venture it and hope someone corrects me if I'm wrong:

If MCAS is disabled, then the airplane will fly very differently from the 737s that everyone with an existing 737 flight rating is used to.

So the plane can fly, but it'll feel different.

And that sure does seem like a problem to get back safely to the ground.

Re: U.S. FAA proposes requiring key Boeing 737 MAX design changes

#25

Post by rootusrootus »

linuxftw wrote: post #19
zaroth wrote: post #3

https://www.faa.gov/news/media/attachments/19_035n-R3-8-3-20... > "To address the unsafe condition, the FAA proposes to require four design changes: (1) installing updated flight control software (with new control laws) for the FCC operational program software (OPS), (2) installing updated MDS display processing computer (DPC) software to generate an AOA disagree alert, (3) revising certain AFM flightcrew operating p…

To me, this reads as a total reduction in the effectiveness of the MCAS. We still have no indication that operating the aircraft without MCAS is safe, therefor if the system fails during a critical moment or is otherwise unable to account for the increased angle of attack, we could see jets plummet to the earth in a stall scenario. Absolutely the worst thing that could happen.

> we could see jets plummet to the earth in a stall scenario

To be fair, when a passenger airliner finds itself in a stall scenario, hitting the ground is not an uncommon result.

Re: U.S. FAA proposes requiring key Boeing 737 MAX design changes

#26

Post by duck »

Nacdor wrote: post #16
Forgeties79 wrote: post #14

Earlier quoted context omitted.

Didn’t an email link with Boeing employees basically saying the exact same thing? “I’d never let my family fly on one” or something?

Looks like it: https://www.businessinsider.com/boeing-employees-wouldnt-let... > 8 months before the first 737 Max crash, 2 Boeing employees talked about how they wouldn't let their families fly on the plane

I would imagine with a company of the size of Boeing you could find a larger group of folks that wouldn't allow their families to fly in any airplane.

Re: U.S. FAA proposes requiring key Boeing 737 MAX design changes

#27

Post by jonathanliu »

cm2187 wrote: post #5

Boeing and the FAA. Feels like an old couple that has to live under the same roof, so it is broken dishes and shouting all day long.

FAA was the battered spouse until Boeing had those two very public crashes. Thanks regulatory capture.

Re: U.S. FAA proposes requiring key Boeing 737 MAX design changes

#28

Post by im_down_w_otp »

zaroth wrote: post #3

https://www.faa.gov/news/media/attachments/19_035n-R3-8-3-20... > "To address the unsafe condition, the FAA proposes to require four design changes: (1) installing updated flight control software (with new control laws) for the FCC operational program software (OPS), (2) installing updated MDS display processing computer (DPC) software to generate an AOA disagree alert, (3) revising certain AFM flightcrew operating p…

That's interesting though I suppose unsurprising.

We did a PoC with Infineon, and demoed at CES this last January, something related to the limitations of Fail-Safe mechanisms in autonomous systems and what changes in deisgn & runtime context are essential for moving from Fail-Safe to Fault-Tolerant systems.

In the case of MCAS this probably works out okay because the remediation is to disable and hand control back to the human (something that I'm frankly shocked wasn't already part of the hazard and risk assessment) in loop. Alternative design approaches could probably extend the safe operational envelope for MCAS to tolerate more (or simultaneous) dimensions of failure, but outside of making MCAS a more valuable feature to market (which isn't that useful since it's baseline essential for the aircraft to even be certifiable) it's easy to see the calculation for not going down that redesign road.

Re: U.S. FAA proposes requiring key Boeing 737 MAX design changes

#30

Post by dimitrios1 »

shajznnckfke wrote: post #17
Nacdor wrote: post #6

Given the option, would anyone choose to book a trip on one of these new Boeing aircraft rather than anything else? I know I wouldn't, my family wouldn't, and none of the friends or co-workers I've discussed this with would. Something tells me airlines are going to be making it even more difficult to determine which aircraft you'll be flying on when you book a ticket. As far as I know they're not required to tell you…

Even though this model has big design flaws and a relatively bad safety record, the absolute level of risk is still pretty low. I knowingly expose myself to larger risks in my day-to-day life. So I won’t lose any sleep over booking a flight on this type of plane.

This is not a good argument.

You can control this level of risk. Taking on any unnecessary risk when you don't have to is not a wise choice.

Post reply on HN