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Boeing 737 MAX crash and the rejection of ridiculous data

philip.greenspun.com

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Re: Boeing 737 MAX crash and the rejection of ridiculous data

#41

Post by greedo »

ronilan wrote: post #35
yongjik wrote: post #8

With all due respect, this sounds too much like the kind of armchair quarterbacking that routinely appears on HN when avionics/politics/astronomy is mentioned, where a lone programmer feels competent enough to criticize an industry for missing "something obvious". I mean, this particular change might have saved the particular 737, but I'd rather hear it from someone who actually knows how 737s fly.

Down by 4 at the Super Bowl, 2nd & Goal, 27 seconds on the play clock, Lynch in the back field. Run the ball About 10 characters of code. Sometimes armchair quarterbacking has a point.

As a Hawks fan, that hurt. Really hurt.

Re: Boeing 737 MAX crash and the rejection of ridiculous data

#42

Post by pdx_flyer »

Ataraxic wrote: post #21

It should be noted in the doomed Air France 447 flight, the plane activated the stall warning because of a high angle of attack that was leading to stall. (thanks pdx for the corrected info) At some point the system rejected the data and stopped the stall warning because the angle of attack was so severe that it considered the data erroneous. This is speculated to have caused the co-pilot to keep pulling back on the…

AF447 was an Airbus 330 which does not have a physical stick shaker. It has a "Stall Stall Stall" warning that sounds and was likely drowned out by the other alarms that were filling the cockpit.

A330s also have disconnected sticks, so when a pilot has input on one side of the plane, that input is not replicated on the other side of the plane.

Re: Boeing 737 MAX crash and the rejection of ridiculous data

#43

Post by chupa-chups »

Ataraxic wrote: post #21

It should be noted in the doomed Air France 447 flight, the plane activated the stall warning because of a high angle of attack that was leading to stall. (thanks pdx for the corrected info) At some point the system rejected the data and stopped the stall warning because the angle of attack was so severe that it considered the data erroneous. This is speculated to have caused the co-pilot to keep pulling back on the…

I suggest to read a bit more about AF447. This was 90% the missing idea of the other pilots that one pilot (i.e. the pilot flying) could be so extremely uneducated(i.e. stupid) to try to pitch up while stalling is imminent/occuring. The remaining 10% is the airbus fuckup of mixing inputs of both sticks.

Re: Boeing 737 MAX crash and the rejection of ridiculous data

#44

Post by supergauntlet »

falcolas wrote: post #32
js2 wrote: post #19

Earlier quoted context omitted.

Philip Greenspun is a highly experienced pilot: https://philip.greenspun.com/flying/milestones

A pilot is not a programmer. A minor, but important distinction. EDIT: Aaaand I'm an idiot. My bad.

https://philip.greenspun.com/teaching/

not only is he a programmer, but he has opinions on teaching programming.

Re: Boeing 737 MAX crash and the rejection of ridiculous data

#45

Post by adolph »

falcolas wrote: post #32
js2 wrote: post #19

Earlier quoted context omitted.

Philip Greenspun is a highly experienced pilot: https://philip.greenspun.com/flying/milestones

A pilot is not a programmer. A minor, but important distinction. EDIT: Aaaand I'm an idiot. My bad.

Are you claiming Greenspun is not a programmer?

https://en.wikipedia.org/wiki/ArsDigita

Re: Boeing 737 MAX crash and the rejection of ridiculous data

#46

Post by fixermark »

quanticle wrote: post #29

On the other hand, one of the contributing factors to the Three Mile Island nuclear disaster was the fact that the temperature sensors were showing their maximum programmed value of 280 degrees Centigrade. The actual core temperature was far far higher, but because the engineers designing the reactor never thought of the meltdown scenario, they programmed the temperature gauge to cut off at 280C, rejecting higher rea…

While this is true, the point that it's worth thinking through the nature and consequences of "obviously erroneous" sensor data is still a valuable exercise holds.

If the temperature is past 280, generally speaking the same steps to diminish temperature can be taken (... I'm speaking broadly; this may not actually be true of nuclear reactors and if it's not, additional sensors with larger ranges were definitely warranted if there's discontinuity in the safety and disaster mitigation strategies at temps higher than 280).

There is no amount of automatic airplane wing trim that can arrest a 70-degree AOA. When the sensor's getting 70 degrees, the failsafe operation would have been to back out of the control calculation and defer to pilots.

Re: Boeing 737 MAX crash and the rejection of ridiculous data

#47

Post by Ataraxic »

pdx_flyer wrote: post #42
Ataraxic wrote: post #21

It should be noted in the doomed Air France 447 flight, the plane activated the stall warning because of a high angle of attack that was leading to stall. (thanks pdx for the corrected info) At some point the system rejected the data and stopped the stall warning because the angle of attack was so severe that it considered the data erroneous. This is speculated to have caused the co-pilot to keep pulling back on the…

AF447 was an Airbus 330 which does not have a physical stick shaker. It has a "Stall Stall Stall" warning that sounds and was likely drowned out by the other alarms that were filling the cockpit. A330s also have disconnected sticks, so when a pilot has input on one side of the plane, that input is not replicated on the other side of the plane.

I will edit my post with the update.

Re: Boeing 737 MAX crash and the rejection of ridiculous data

#48

Post by sesteel »

yongjik wrote: post #8

With all due respect, this sounds too much like the kind of armchair quarterbacking that routinely appears on HN when avionics/politics/astronomy is mentioned, where a lone programmer feels competent enough to criticize an industry for missing "something obvious". I mean, this particular change might have saved the particular 737, but I'd rather hear it from someone who actually knows how 737s fly.

This seems equivalent to "it is just a button, how hard can it be?" People outside of software rarely see the complexity they are suggesting or asking for.

Re: Boeing 737 MAX crash and the rejection of ridiculous data

#50

Post by ronilan »

greedo wrote: post #41
ronilan wrote: post #35

Earlier quoted context omitted.

Down by 4 at the Super Bowl, 2nd & Goal, 27 seconds on the play clock, Lynch in the back field. Run the ball About 10 characters of code. Sometimes armchair quarterbacking has a point.

As a Hawks fan, that hurt. Really hurt.

The agony: https://www.youtube.com/watch?v=U7rPIg7ZNQ8
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