U.S. FAA proposes requiring key Boeing 737 MAX design changes • Hacker News Board

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

#121

Post by shock » Mon, Aug 03, 2020, 11:28 PM UTC

curryst wrote: post #116

shock wrote: 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…

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 approxi…

> Measuring the risk of travel in terms of hours seems largely pointless, unless I'm missing something.

Again, it depends on what you're trying to measure. If you're trying to quantify the risk of dying by accident at a certain hour, what activity you are doing in that hour is highly relevant.

If you are trying to quantify the risk of dying by accident while going from A to B, then it's not (that) relevant.

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

#122

Post by shock » Mon, Aug 03, 2020, 11:37 PM UTC

shajznnckfke wrote: post #113

shock wrote: 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.

Another way to think about it would be: you have (roughly) the same chance of dying in a 3 hour flight as in an 9 hour bus ride.

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

#123

Post by YetAnotherNick » Mon, Aug 03, 2020, 11:40 PM UTC

zucker42 wrote: post #48

dimitrios1 wrote: post #30

Earlier quoted context omitted.

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.

Obviously you'd choose the safer plane if it's equally convenient. But if the absolute risk is low and there's no other plane at the same time, or the alternatives cost 2x as much, it's reasonable to be willing to fly on a more dangerous plane.

But the alternatives are of similar price range.

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

#124

Post by linuxftw » Tue, Aug 04, 2020, 12:18 AM UTC

tgsovlerkhgsel wrote: post #105

tzs wrote: post #70

Earlier quoted context omitted.

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…

But if a MCAS failure and an unexpected unusual attitude does line up, there will be another crater.

This seems to be the part that everyone's missing. "Oh, this rarely happens" is ambiguous, we don't have any data on how often MCAS operated correctly during flights.

Also, in events that 'rarely happen' one of which is approaching a stall (according to the FAA's report), is it safe to disable the system in the actual scenario when encountered? It doesn't seem so. I can't see how both "Need this system for extremely rare scenario" and "Disabling this system because scenario is extremely rare is okay" can both be true.

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

#125

Post by linuxftw » Tue, Aug 04, 2020, 12:20 AM UTC

l31g wrote: post #94

linuxftw wrote: post #19

Earlier quoted context omitted.

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.

MCAS is only useful in very extreme situations rarely seen in normal flight. Most pilots will never be in a situation where MCAS is useful.

> Most pilots will never be in a situation where MCAS is useful.

And if they are in the situation? Also, there's no data on how many times MCAS activated on non-crashing flights with valid data, so this statement is 100% speculation.

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

#126

Post by jonny_eh » Tue, Aug 04, 2020, 12:29 AM UTC

YetAnotherNick wrote: post #123

zucker42 wrote: post #48

Earlier quoted context omitted.

Obviously you'd choose the safer plane if it's equally convenient. But if the absolute risk is low and there's no other plane at the same time, or the alternatives cost 2x as much, it's reasonable to be willing to fly on a more dangerous plane.

But the alternatives are of similar price range.

Depends on the route

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

#127

Post by jonathanliu » Tue, Aug 04, 2020, 12:59 AM UTC

khuey wrote: post #72

jonathanliu wrote: post #31

Earlier quoted context omitted.

Even the non-MAX 737s have had issues recently. https://www.usatoday.com/story/travel/airline-news/2020/07/2...

Planes don't typically sit on the ground for several months without being used so this is a little more forgivable.

I agree, but I'm still going to avoid flying for awhile! (And I was up to 21 flights by March.)

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

#128

Post by jonathanliu » Tue, Aug 04, 2020, 1:01 AM UTC

yborg wrote: post #99

jonathanliu wrote: post #27

Earlier quoted context omitted.

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

In a way, it's fortunate that the two MAX crashes happened overseas. If they had happened in the US, Boeing could have used its regulatory leverage to cover up the problem for a few more crashes.

Hmm I wonder how true that is (I have no personal experience/knowledge). I feel like two large crashes would get a very hard look by the NTSB.

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

#129

Post by tgsovlerkhgsel » Tue, Aug 04, 2020, 1:19 AM UTC

linuxftw wrote: post #124

tgsovlerkhgsel wrote: post #105

Earlier quoted context omitted.

But if a MCAS failure and an unexpected unusual attitude does line up, there will be another crater.

This seems to be the part that everyone's missing. "Oh, this rarely happens" is ambiguous, we don't have any data on how often MCAS operated correctly during flights. Also, in events that 'rarely happen' one of which is approaching a stall (according to the FAA's report), is it safe to disable the system in the actual scenario when encountered? It doesn't seem so. I can't see how both "Need this system for extremely…

> I can't see how both "Need this system for extremely rare scenario" and "Disabling this system because scenario is extremely rare is okay" can both be true.

The benevolent interpretation is:

a) the plane being in a situation where the system is required is rare, but frequent enough that the risk wouldn't be acceptable without MCAS.

b) MCAS breaking is rare, but frequent enough that we can't allow it to fly the plane into the ground when it does (as has been demonstrated).

c) Both things happening at the same time is so exceedingly rare that a crater is an acceptable outcome, just like we accept that all engines simultaneously failing at the same time during take-off will likely result in a crash.

(compare: https://commons.wikimedia.org/wiki/File:FAA_8040.4B_Risk_mat...)

That said, I hope EASA takes a very close look instead of blindly trusting the FAA again...

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

#130

Post by random314 » Tue, Aug 04, 2020, 1:26 AM UTC

joking wrote: post #76

random314 wrote: post #67

Earlier quoted context omitted.

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?

If it was only over a few weeks probably not, but I’m pretty sure that your past few weeks diet is representative of your average diet during the last ten years, and that could be riskier than a 737 max flight.

You have completely changed the premise of the argument now. Yes lifestyle changes have a bigger effect than a single plane ride. This calculus changes immediately if you make 1000 plane rides on a MAX. A typical diet over a few weeks is definitely safer than a MAX ride.