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

reuters.com

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

#111

Earlier quoted context omitted.

I would absolutely love to see a log of food you've eaten over the past few weeks.

I can't see any calculations by which a typical diet over a few weeks is riskier than a 737 MAX. Have you built such a risk model?

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

#112
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.

Can anyone locate statistics on the total numbers of passengers, or passenger-miles that have happened on a 737 MAX? It would make it possible to run a bunch of estimated risk calculations instead of taking a handwavy intuition-based approach.

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

#113
post #101
post #78

Earlier quoted context omitted.

How are you getting to the airport? However the method, it's far more likely to injure you than flying on a 737 MAX.

> However the method, it's far more likely to injure you than flying on a 737 MAX. That depends. If you take a bus to go to the airport and it takes you an hour to get there, then your flight also lasts an hour (for simplicity's sake), you are almost 3 times more likely(on average) to die during the flight than you are during the bus ride [0]. In terms of number of journeys by plane and bus, for the same number of jo…

Other than that one time JetBlue ran a shuttle flight from one end of LA to the other for a publicity stunt, it don’t think this comparison makes sense. An hour bus ride isn’t a substitute for an hour plane ride.

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

#114
post #101
post #78

Earlier quoted context omitted.

How are you getting to the airport? However the method, it's far more likely to injure you than flying on a 737 MAX.

> However the method, it's far more likely to injure you than flying on a 737 MAX. That depends. If you take a bus to go to the airport and it takes you an hour to get there, then your flight also lasts an hour (for simplicity's sake), you are almost 3 times more likely(on average) to die during the flight than you are during the bus ride [0]. In terms of number of journeys by plane and bus, for the same number of jo…

This is a great argument that I'd never heard before. Never knew about the per-hour statistics either.

All that being said, it sounds like one can "control the level of risk" by taking a bus instead of driving/Uber/Lyft/taxi to the airport, but choosing to do the latter is an example of "taking on any unnecessary risk when you don't have to [which] is not a wise choice". And yet it is a completely reasonable thing to do.

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

#115
post #101

Earlier quoted context omitted.

> However the method, it's far more likely to injure you than flying on a 737 MAX. That depends. If you take a bus to go to the airport and it takes you an hour to get there, then your flight also lasts an hour (for simplicity's sake), you are almost 3 times more likely(on average) to die during the flight than you are during the bus ride [0]. In terms of number of journeys by plane and bus, for the same number of jo…

Other than that one time JetBlue ran a shuttle flight from one end of LA to the other for a publicity stunt, it don’t think this comparison makes sense. An hour bus ride isn’t a substitute for an hour plane ride.

He was responding to the claim that "you're more likely to die on your way to the airport".

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

#116
post #101
post #78

Earlier quoted context omitted.

How are you getting to the airport? However the method, it's far more likely to injure you than flying on a 737 MAX.

> However the method, it's far more likely to injure you than flying on a 737 MAX. That depends. If you take a bus to go to the airport and it takes you an hour to get there, then your flight also lasts an hour (for simplicity's sake), you are almost 3 times more likely(on average) to die during the flight than you are during the bus ride [0]. In terms of number of journeys by plane and bus, for the same number of jo…

Measuring the risk of travel in terms of hours seems largely pointless, unless I'm missing something. It equates an hour bus ride with an hour plane ride, which are not interchangeable, so it makes sense that the associated risks are also not interchangeable.

You could account for the additional time it takes to go on a bus to adjust for the longer duration of risk, but at that point it seems like you're just approximating for risk per km.

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

#117
post #66

Earlier quoted context omitted.

Triple is not needed, just double with a redundant "disagree" alarm. Once the pilot knows there's one bad AOA, they can lock out the bad one as an input to the autopilot/MCAS, or hand fly without automation. Of course this is all a bunch of new software and training though.

How do you know which one is bad?

Attitude indicators are gyroscopic and themselves redundant. If you can get the plane into level flight and then examine the AOA sensors, they should be close to a known value (see picture) if you do some math. Not saying this is a good idea.

https://orangeflighttraining.com.au/images/aviation-AoA-pitc...

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

#118

Earlier quoted context omitted.

> 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.

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

#119

Earlier quoted context omitted.

Other than that one time JetBlue ran a shuttle flight from one end of LA to the other for a publicity stunt, it don’t think this comparison makes sense. An hour bus ride isn’t a substitute for an hour plane ride.

He was responding to the claim that "you're more likely to die on your way to the airport".

Thank you. I thought it was self evident. I've amended my post to make it clearer.

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

#120
post #70

Earlier quoted context omitted.

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.

MCAS only kicks in at high angle of attack with the flaps up. I believe that most flights never come near having it activate. If it disables due to faulty sensors and the pilots are told it is disabled, most flights won't have to do anything different at that point. The plane will handle just like it normally does. If there are flights that are supposed to have maneuvers that would trigger MCAS, pilots are going to n…

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