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> But months after the planes were flying, company engineers realized that the warning light worked only on planes whose customers had bought a different, optio

> But months after the planes were flying, company engineers realized that the warning light worked only on planes whose customers had bought a different, optional indicator. If I am to read this correctly, the angle-of-attack disagree light is installed on all Boeing 737-MAX aircraft. For customers who did not buy on optional additional indicator, the angle-of-attack disagree light was always off, even if there is a disagreement between to sensors of the angle of attack of the aircraft. Doesn't this seem dangerous in-and-of itself? If a pilot assumes that the light is off because there is not a disagreement, instead of because there is no information available, she is acting on incorrect information, and might try to address problems unrelated to the actual problem. Also, pilot may switch aircraft and expect the same functionality of safety features and may make incorrect assumptions about the functioning of this light.

peteretep 7y ago
> Doesn't this seem dangerous in-and-of itself? To me, more dangerous, is that some safety systems are considered optional. Surely the plane either needs a safety feature or not, and it shouldn't be down to someone at an airline to make a decision on?
- firethief 7y ago
  Different countries have different standards of safety, and different budgets. Boeing got more $$$ from airlines in the US by making planes in Ethiopia and Indonesia less safe. Yay capitalism.
  - ddalex 7y ago
    Not less safe. Perhaps not as safe at others. Such as of those where the front doesn't fell off.
    - FabHK 7y ago
      Well, it's not built of cardboard and rubber... Does everyone know this delicious skit? "Clarke and Dawe - The Front Fell Off" https://www.youtube.com/watch?v=3m5qxZm_JqM https://www.youtube.com/watch?v=3m5qxZm_JqM
    - firethief 7y ago
      I mean less safe relative to shipping the same hardware with the warning feature enabled, which they could have done at no cost except the loss of loss of price discrimination (which I'm sure was substantial, but probably not enough that they don't now regret it)
  - fit2rule 7y ago
    Since the 737 MAX also has military customers, it may be more likely that Boeing's design of the modular components was compromised by the need to accommodate military specs, which often leave off 'unnecessary consumer safety options' ..
  - Haga 7y ago
    Maybe should have run adds in the cockpit
  - briandear 7y ago
    That’s weird to say. Lion Air is a sloppy, cheapskate airline — look at their horrible maintenance and crash history for evidence of that. That they didn’t want to pay slightly extra for additional options on the plane was their choice. And Ethiopian is a flag carrier: they could have easily gotten the extra option, but likely some accountant thought it wasn’t necessary. Who spends over $100 million on an airplane and then declines a $1 million safety option?
    - marksweston 7y ago
      Who ships safety-critical features as an optional extra?
      - bumby 7y ago
        There's levels to safety-criticality so these aren't binary decisions. Often they are based on severity/probability/detectability measures. For example, airbags on your car may be mandatory but automatic emergency braking not so much.
        marksweston 7y ago
        I agree, but was responding to a post that was heavily criticising Lion Air for not paying for the option and implicitly laying the blame for the crash at their door. Either the option was safety critical, in which case Boeing had no business making it optional, or it wasn’t, in which case blaming Lion Air is unreasonable. Given that thanks to Boeing, the Lion Air crew didn’t even know the MCAS subsystem existed, and that MCAS would continue to rely on the single faulty sensor however many extra redundancies were installed, the decision not to buy seems kind of irrelevant.
        bumby 7y ago
        > Either the option was safety critical, in which case Boeing had no business making it optional This is the part I was trying to clarify. I don't know Boeing's internal processes, but there certainly could be options that are safety-critical but still optional because they are ranked low enough on the severity/probability/detectability scale. I agree that it's wrong to blame Lion Air as the consumer. The fault seems to be in Boeing misapplying the risk categorization.
  - Arnt 7y ago
    You appear to assume that the 20% of aircraft with the optional feature are in the US. That's possible, but... Citation needed.
    - deleted 7y ago
      [deleted]
    - firethief 7y ago
      It's not a random assumption. I read in some recent article that the airlines in the US have the feature--sorry I don't remember which, but you can look it up as easily as I.
      - Arnt 7y ago
        How can I look that up? You're the one who made the factual statement. I'm not the one that's obliged to back that up. Wikipedia lists the customers, and the number of aircraft delivered to US airlines is a good match for the 20% of aircraft that are said to have that feature. However, that assumption implies that 0% of leasing companies ordered it, that 0% of Canadian customers did, that the American airlines bought all their aircraft and didn't lease any, etc. Might all be true but you can see why I asked for a citation. https://en.wikipedia.org/wiki/List_of_Boeing_737_MAX_orders_and_deliveries https://en.wikipedia.org/wiki/List_of_Boeing_737_MAX_orders_...
- Nasrudith 7y ago
  The really sociopathic part is the upselling of it as a separate feature when the actual marginal costs are nill. It is one thing if they have to retrofit it but the 737 is newer - just doing it the most expensive option seems like it should give the most logistical savings and be the best for long term profit. I mean people look at the safety record and a crash makes them look bad even if it was pilot error.
  - FabHK 7y ago
    Yeah, that's jarring - it's not even that Boeing has to put in extra parts or even extra software. It's just flipping a switch in the software.
- mikekchar 7y ago
  There is usually no such thing as "safe" or "not safe". It's more like "X% chance to happen". X might be really, really small, but not zero. Usually you can make X arbitrarily small, but the amount of money needed grows non-linearly. Do you pay 10x the price of an aircraft to reduce the chances a problem so that it goes from happening once every 100 years to once every 1000 years? Who should make the decision whether an airplane is "safe enough"? Should it be the buyer who wants the safest plane? If you did that then rich airlines could keep out new competition by specifying safety features that make airplanes more expensive than they need to be. Should it be the country where the airline is based? But different airlines are based in different countries. Should there be options so that one country can specify higher standards than others? Basically, that's how you get where we are I think. I'm not sure how you avoid that.
  - deleted 7y ago
    [deleted]
  - onion2k 7y ago
    Who should make the decision whether an airplane is "safe enough"? How about these guys? https://en.wikipedia.org/wiki/International_Aviation_Safety_Assessment_Program https://en.wikipedia.org/wiki/International_Aviation_Safety_...
  - jrochkind1 7y ago
    it's worth pointing out, however, that it was a software-only feature that they turned on or off depending on whether the customer had paid. If I understand right? I think that changes the calculus of "Do you pay 10x the price of an aircraft to reduce the chances a problem so that it goes from happening once every 100 years to once every 1000 years" They had already invested the money to develop the feature. Delivering a plane with or without it to a customer had the same cost. If the customer paid more, they got the safety feature turned on, the end.
    - grkvlt 7y ago
      > Delivering a plane with or without it to a customer had the same cost Not exactly, surely. The ongoing/recurring costs to Boeing would be increased with the feature enabled - it's another thing that can go wrong and must be monitored, it changes support requirements and the overall software runtime complexity. I assume that would get factored in, somehow...
- edelans 7y ago
  Did you buy all the optional safety features of your car model ?
  - pcl 7y ago
    Last time I bought a new car, this was actually a pretty important factor for me -- one car was nominally cheaper, but had a number of optional safety features (like rear passenger pillar airbags, IIRC), and they brought the price to parity with the other car I was considering. I figured I'd hate myself if I declined to buy some optional safety features and ended up with an injured passenger as a result, so ended up including all of them in the purchase price, and eventually went with the higher-base-price car.
- lwhi 7y ago
  It's a tool. Without the warning you can add up the approximate weight of passengers and luggage, and check it's below the maximum. I'd like to think this is done as a matter of course.
  - chaboud 7y ago
    I'm not sure what you're responding to, but AoA indicators have very little to do with weight and balance. Fuel loads, critical airspeeds, and maneuvering characteristics are indeed governed by weight and balance. That has nothing to do with AoA reading mismatch indicators. Was there a separate question about automatic weight and balance measurement as a feature?
- _pmf_ 7y ago
  > Surely the plane either needs a safety feature or not, and it shouldn't be down to someone at an airline to make a decision on? To you own the safest car that is available?
  - magduf 7y ago
    Actually, when I bought my last car, I did get the trim level that had all the extra safety features. However, I'm not transporting passengers for money and accepting liability for passengers' lives; airlines do, so their financial calculation should be very different from Joe Blow private car buyer. Finally, if I understand correctly, these extra safety features were software only, meaning they don't cost the manufacturer anything to add on, so there's no excuse to not make them standard. On cars, the extra safety features require expensive sensors, so they really do add to the BOM cost of the car, and putting them on an economy car really could push the price too high for buyers to afford, so carmakers put them in higher-cost models to help make them more commonplace and then move them into lower-cost models as the volumes increase and economies of scale make costs lower.
- bumby 7y ago
  It has to do with the classification during the system safety analysis (SSA). IIRC, the MCAS was classified as 'hazardous' if failed but not 'catastrophic'. If it were classified as a higher hazard level, it presumably would levy additional requirements. It's a risk-based approach, which sounds like they failed to appropriately classify the risk. https://www.seattletimes.com/business/boeing-aerospace/failed-certification-faa-missed-safety-issues-in-the-737-max-system-implicated-in-the-lion-air-crash/ https://www.seattletimes.com/business/boeing-aerospace/faile...
gordon_freeman 7y ago
My question is if this ON-OFF switch was really a safety feature (and I believe it was and is) then why FAA turned the blind eye during the aircraft certification process and did not ask Boeing to make it Standard on every MAX plane they ship? Shouldn't the blame for those 2 air disasters be equally then shared by FAA along with Boeing because every air regulation agency in the world looks at FAA as a leading org among them all. Edit (as seeing downvote due to the possible tone of the comment): What I am saying is basically this should have been flagged by the FAA during the certification process. Maybe that was not part of the process but making sure to check which optional features offered are safety related could be absolutely critical for air safety. Edit 2: I meant ON-OFF Light here
- deleted 7y ago
  [deleted]
- cjbprime 7y ago
  I have no idea what you mean. Which ON-OFF switch? No-one was talking about an ON-OFF switch. There is no optional ON-OFF switch. The article is about an optional warning. Not an optional switch.
  - gordon_freeman 7y ago
    I meant the ON-OFF Light -- the AoA disagree light that turns on when both sensors have different readings (during a possible malfunction of the sensor with bad data) and keeps off when both sensors have same reading on the angle of attack.
    - cjbprime 7y ago
      Oh. Then the answer appears to be that Boeing misled the FAA into thinking that MCAS didn't have the capability to cause a catastrophic failure, by understating the degree of control authority it was capable of, and therefore AoA sensor failure (and the disagree light) wasn't tied to any airworthiness issue. I don't think a light (rather than annunciator) can be a very serious safety feature in any case, simply because in an emergency pilots aren't going to be looking at random places throughout the cockpit to see which small lights are on. They're going to be looking at the central EICAS display, which is what they're trained to do.
coba33 7y ago
Just one correction: instead of "she is acting on incorrect information" it is preferred to use "xir is acting on incorrect information". It will get you better free cookies at Google
droithomme 7y ago
> Doesn't this seem dangerous in-and-of itself? I would describe it as extreme criminal negligence with wanton disregard for human life.
- sgt101 7y ago
  I'll see that, and raise with "I would describe it as extreme criminal negligence with wanton disregard for human life that has resulted in more than 300 deaths."
sonnyblarney 7y ago
The bigger issue is that there should be no price discrimination on safety gear unless it's complex and expensive.
- sokoloff 7y ago
  Set the rules that way and you're likely to get a lot of safety gear that meets the "is complex and expensive" test.
AnssiH 7y ago
The "light" is just a warning text that appears on the flight display, so the "no light installed" and "light installed but off" states are not distinguishable (as far as I have understood it). http://www.boeing.com/resources/boeingdotcom/commercial/737max/updates/AOA_VaneIndicator_AoA_Disagree_lg.jpg http://www.boeing.com/resources/boeingdotcom/commercial/737m...
- sgustard 7y ago
  Thank you for sharing that image. Now the UX question is: would that small bit of yellow text in a cockpit with hundreds of visible UI elements make any difference?
  - radiorental 7y ago
    It would imho. If the plane is in a failure mode, the user would search the UI specifically for error messages. As a UXer I would _assume_ error messages would be in a consistent section of UI real estate. However, even if this is not the case I would expect both experience and training to mitigate the "can't find the error message among all das blinkenlights"
  - deleted 7y ago
    [deleted]
  - t0mas88 7y ago
    Yes absolutely, all failures are announced in that same place on the PFD. The pilot flying has eyes on the PFD continuously, only looking away for a few seconds at a time if handling other systems. Essentially when flying instruments you "scan" the 4 primary pieces of information in the middle of that screen every few seconds. On top of that there is an audible reminder when a new failure annunciator appears, so even if they were on autopilot and not paying attention (rare so early after takeoff) they would hear it and look.
- inferiorhuman 7y ago
  The "light" is just a warning text that appears on the flight display, so the "no light installed" and "light installed but off" states are not distinguishable (as far as I have understood it). They're absolutely different. If you're a pilot and you expect to see an error message when the two alpha vanes disagree, you'll be lulled into a false sense of security when that text never appears even in the case of a failure. A pilot needs to be able to trust all of the instruments in the plane.
deleted 7y ago
[deleted]
deleted 7y ago
[deleted]
chopin 7y ago
This disagree doesn't help anything if you don't know that MCAS exists and is coupled to the sensors. Afaik only Brazil regulators insisted of telling pilots of MCAS existence (though I don't know whether the implications where clear to pilots).
raxxorrax 7y ago
I am surprised these mechanisms come in optional packages. What else do I have to order separately? Wings, engines, ruder? Is this some kind of airplane DLC and can I get the season pass for less money?
jrochkind1 7y ago
I hadn't realized planes were sold with software-only features that were only turned on if you paid more. Which is what sounds like happened, right? I guess I shouldn't be surprised, this makes sense as a money-maker, and is how software is (necessarily) sold. When you have to pay extra for certain software features, whether or not they were actually included in the binary you have as a lesser-payer, it could have been, software is intangible and has no extra per-unit cost to include the "mechanism" once developed. This makes sense as a business model for selling software, in that that's how software works. But yeah, I hadn't realized planes were sold that way. When we're talking about "features" that are pilot dashboard indicators... it really doesn't seem wise. Are there any pilot dashboard indicators that would be sold as add-ons that wouldn't increase safety were they there? I mean, what's a dashboard indicator for if not making it easier for the pilot to fly the plane? If you have to pay extra for some actual physical device, that's one thing, the physical device has to be installed. But when they're just holding back safety features with no extra per-unit cost that could simply be switched on if you paid... does not make me feel great about flying.

peteretep 7y ago

> Doesn't this seem dangerous in-and-of itself? To me, more dangerous, is that some safety systems are considered optional. Surely the plane either needs a safety feature or not, and it shouldn't be down to someone at an airline to make a decision on?

firethief 7y ago
Different countries have different standards of safety, and different budgets. Boeing got more $$$ from airlines in the US by making planes in Ethiopia and Indonesia less safe. Yay capitalism.
- ddalex 7y ago
  Not less safe. Perhaps not as safe at others. Such as of those where the front doesn't fell off.
  - FabHK 7y ago
    Well, it's not built of cardboard and rubber... Does everyone know this delicious skit? "Clarke and Dawe - The Front Fell Off" https://www.youtube.com/watch?v=3m5qxZm_JqM https://www.youtube.com/watch?v=3m5qxZm_JqM
  - firethief 7y ago
    I mean less safe relative to shipping the same hardware with the warning feature enabled, which they could have done at no cost except the loss of loss of price discrimination (which I'm sure was substantial, but probably not enough that they don't now regret it)
- fit2rule 7y ago
  Since the 737 MAX also has military customers, it may be more likely that Boeing's design of the modular components was compromised by the need to accommodate military specs, which often leave off 'unnecessary consumer safety options' ..
- Haga 7y ago
  Maybe should have run adds in the cockpit
- briandear 7y ago
  That’s weird to say. Lion Air is a sloppy, cheapskate airline — look at their horrible maintenance and crash history for evidence of that. That they didn’t want to pay slightly extra for additional options on the plane was their choice. And Ethiopian is a flag carrier: they could have easily gotten the extra option, but likely some accountant thought it wasn’t necessary. Who spends over $100 million on an airplane and then declines a $1 million safety option?
  - marksweston 7y ago
    Who ships safety-critical features as an optional extra?
    - bumby 7y ago
      There's levels to safety-criticality so these aren't binary decisions. Often they are based on severity/probability/detectability measures. For example, airbags on your car may be mandatory but automatic emergency braking not so much.
      - marksweston 7y ago
        I agree, but was responding to a post that was heavily criticising Lion Air for not paying for the option and implicitly laying the blame for the crash at their door. Either the option was safety critical, in which case Boeing had no business making it optional, or it wasn’t, in which case blaming Lion Air is unreasonable. Given that thanks to Boeing, the Lion Air crew didn’t even know the MCAS subsystem existed, and that MCAS would continue to rely on the single faulty sensor however many extra redundancies were installed, the decision not to buy seems kind of irrelevant.
        bumby 7y ago
        > Either the option was safety critical, in which case Boeing had no business making it optional This is the part I was trying to clarify. I don't know Boeing's internal processes, but there certainly could be options that are safety-critical but still optional because they are ranked low enough on the severity/probability/detectability scale. I agree that it's wrong to blame Lion Air as the consumer. The fault seems to be in Boeing misapplying the risk categorization.
- Arnt 7y ago
  You appear to assume that the 20% of aircraft with the optional feature are in the US. That's possible, but... Citation needed.
  - deleted 7y ago
    [deleted]
  - firethief 7y ago
    It's not a random assumption. I read in some recent article that the airlines in the US have the feature--sorry I don't remember which, but you can look it up as easily as I.
    - Arnt 7y ago
      How can I look that up? You're the one who made the factual statement. I'm not the one that's obliged to back that up. Wikipedia lists the customers, and the number of aircraft delivered to US airlines is a good match for the 20% of aircraft that are said to have that feature. However, that assumption implies that 0% of leasing companies ordered it, that 0% of Canadian customers did, that the American airlines bought all their aircraft and didn't lease any, etc. Might all be true but you can see why I asked for a citation. https://en.wikipedia.org/wiki/List_of_Boeing_737_MAX_orders_and_deliveries https://en.wikipedia.org/wiki/List_of_Boeing_737_MAX_orders_...
Nasrudith 7y ago
The really sociopathic part is the upselling of it as a separate feature when the actual marginal costs are nill. It is one thing if they have to retrofit it but the 737 is newer - just doing it the most expensive option seems like it should give the most logistical savings and be the best for long term profit. I mean people look at the safety record and a crash makes them look bad even if it was pilot error.
- FabHK 7y ago
  Yeah, that's jarring - it's not even that Boeing has to put in extra parts or even extra software. It's just flipping a switch in the software.
mikekchar 7y ago
There is usually no such thing as "safe" or "not safe". It's more like "X% chance to happen". X might be really, really small, but not zero. Usually you can make X arbitrarily small, but the amount of money needed grows non-linearly. Do you pay 10x the price of an aircraft to reduce the chances a problem so that it goes from happening once every 100 years to once every 1000 years? Who should make the decision whether an airplane is "safe enough"? Should it be the buyer who wants the safest plane? If you did that then rich airlines could keep out new competition by specifying safety features that make airplanes more expensive than they need to be. Should it be the country where the airline is based? But different airlines are based in different countries. Should there be options so that one country can specify higher standards than others? Basically, that's how you get where we are I think. I'm not sure how you avoid that.
- deleted 7y ago
  [deleted]
- onion2k 7y ago
  Who should make the decision whether an airplane is "safe enough"? How about these guys? https://en.wikipedia.org/wiki/International_Aviation_Safety_Assessment_Program https://en.wikipedia.org/wiki/International_Aviation_Safety_...
- jrochkind1 7y ago
  it's worth pointing out, however, that it was a software-only feature that they turned on or off depending on whether the customer had paid. If I understand right? I think that changes the calculus of "Do you pay 10x the price of an aircraft to reduce the chances a problem so that it goes from happening once every 100 years to once every 1000 years" They had already invested the money to develop the feature. Delivering a plane with or without it to a customer had the same cost. If the customer paid more, they got the safety feature turned on, the end.
  - grkvlt 7y ago
    > Delivering a plane with or without it to a customer had the same cost Not exactly, surely. The ongoing/recurring costs to Boeing would be increased with the feature enabled - it's another thing that can go wrong and must be monitored, it changes support requirements and the overall software runtime complexity. I assume that would get factored in, somehow...
edelans 7y ago
Did you buy all the optional safety features of your car model ?
- pcl 7y ago
  Last time I bought a new car, this was actually a pretty important factor for me -- one car was nominally cheaper, but had a number of optional safety features (like rear passenger pillar airbags, IIRC), and they brought the price to parity with the other car I was considering. I figured I'd hate myself if I declined to buy some optional safety features and ended up with an injured passenger as a result, so ended up including all of them in the purchase price, and eventually went with the higher-base-price car.
lwhi 7y ago
It's a tool. Without the warning you can add up the approximate weight of passengers and luggage, and check it's below the maximum. I'd like to think this is done as a matter of course.
- chaboud 7y ago
  I'm not sure what you're responding to, but AoA indicators have very little to do with weight and balance. Fuel loads, critical airspeeds, and maneuvering characteristics are indeed governed by weight and balance. That has nothing to do with AoA reading mismatch indicators. Was there a separate question about automatic weight and balance measurement as a feature?
_pmf_ 7y ago
> Surely the plane either needs a safety feature or not, and it shouldn't be down to someone at an airline to make a decision on? To you own the safest car that is available?
- magduf 7y ago
  Actually, when I bought my last car, I did get the trim level that had all the extra safety features. However, I'm not transporting passengers for money and accepting liability for passengers' lives; airlines do, so their financial calculation should be very different from Joe Blow private car buyer. Finally, if I understand correctly, these extra safety features were software only, meaning they don't cost the manufacturer anything to add on, so there's no excuse to not make them standard. On cars, the extra safety features require expensive sensors, so they really do add to the BOM cost of the car, and putting them on an economy car really could push the price too high for buyers to afford, so carmakers put them in higher-cost models to help make them more commonplace and then move them into lower-cost models as the volumes increase and economies of scale make costs lower.
bumby 7y ago
It has to do with the classification during the system safety analysis (SSA). IIRC, the MCAS was classified as 'hazardous' if failed but not 'catastrophic'. If it were classified as a higher hazard level, it presumably would levy additional requirements. It's a risk-based approach, which sounds like they failed to appropriately classify the risk. https://www.seattletimes.com/business/boeing-aerospace/failed-certification-faa-missed-safety-issues-in-the-737-max-system-implicated-in-the-lion-air-crash/ https://www.seattletimes.com/business/boeing-aerospace/faile...

gordon_freeman 7y ago

My question is if this ON-OFF switch was really a safety feature (and I believe it was and is) then why FAA turned the blind eye during the aircraft certification process and did not ask Boeing to make it Standard on every MAX plane they ship? Shouldn't the blame for those 2 air disasters be equally then shared by FAA along with Boeing because every air regulation agency in the world looks at FAA as a leading org among them all. Edit (as seeing downvote due to the possible tone of the comment): What I am saying is basically this should have been flagged by the FAA during the certification process. Maybe that was not part of the process but making sure to check which optional features offered are safety related could be absolutely critical for air safety. Edit 2: I meant ON-OFF Light here

deleted 7y ago
[deleted]
cjbprime 7y ago
I have no idea what you mean. Which ON-OFF switch? No-one was talking about an ON-OFF switch. There is no optional ON-OFF switch. The article is about an optional warning. Not an optional switch.
- gordon_freeman 7y ago
  I meant the ON-OFF Light -- the AoA disagree light that turns on when both sensors have different readings (during a possible malfunction of the sensor with bad data) and keeps off when both sensors have same reading on the angle of attack.
  - cjbprime 7y ago
    Oh. Then the answer appears to be that Boeing misled the FAA into thinking that MCAS didn't have the capability to cause a catastrophic failure, by understating the degree of control authority it was capable of, and therefore AoA sensor failure (and the disagree light) wasn't tied to any airworthiness issue. I don't think a light (rather than annunciator) can be a very serious safety feature in any case, simply because in an emergency pilots aren't going to be looking at random places throughout the cockpit to see which small lights are on. They're going to be looking at the central EICAS display, which is what they're trained to do.

coba33 7y ago

Just one correction: instead of "she is acting on incorrect information" it is preferred to use "xir is acting on incorrect information". It will get you better free cookies at Google

droithomme 7y ago

> Doesn't this seem dangerous in-and-of itself? I would describe it as extreme criminal negligence with wanton disregard for human life.

sgt101 7y ago
I'll see that, and raise with "I would describe it as extreme criminal negligence with wanton disregard for human life that has resulted in more than 300 deaths."

sonnyblarney 7y ago

The bigger issue is that there should be no price discrimination on safety gear unless it's complex and expensive.

sokoloff 7y ago
Set the rules that way and you're likely to get a lot of safety gear that meets the "is complex and expensive" test.

AnssiH 7y ago

The "light" is just a warning text that appears on the flight display, so the "no light installed" and "light installed but off" states are not distinguishable (as far as I have understood it). http://www.boeing.com/resources/boeingdotcom/commercial/737max/updates/AOA_VaneIndicator_AoA_Disagree_lg.jpg http://www.boeing.com/resources/boeingdotcom/commercial/737m...

sgustard 7y ago
Thank you for sharing that image. Now the UX question is: would that small bit of yellow text in a cockpit with hundreds of visible UI elements make any difference?
- radiorental 7y ago
  It would imho. If the plane is in a failure mode, the user would search the UI specifically for error messages. As a UXer I would _assume_ error messages would be in a consistent section of UI real estate. However, even if this is not the case I would expect both experience and training to mitigate the "can't find the error message among all das blinkenlights"
- deleted 7y ago
  [deleted]
- t0mas88 7y ago
  Yes absolutely, all failures are announced in that same place on the PFD. The pilot flying has eyes on the PFD continuously, only looking away for a few seconds at a time if handling other systems. Essentially when flying instruments you "scan" the 4 primary pieces of information in the middle of that screen every few seconds. On top of that there is an audible reminder when a new failure annunciator appears, so even if they were on autopilot and not paying attention (rare so early after takeoff) they would hear it and look.
inferiorhuman 7y ago
The "light" is just a warning text that appears on the flight display, so the "no light installed" and "light installed but off" states are not distinguishable (as far as I have understood it). They're absolutely different. If you're a pilot and you expect to see an error message when the two alpha vanes disagree, you'll be lulled into a false sense of security when that text never appears even in the case of a failure. A pilot needs to be able to trust all of the instruments in the plane.

deleted 7y ago

[deleted]

deleted 7y ago

[deleted]

chopin 7y ago

This disagree doesn't help anything if you don't know that MCAS exists and is coupled to the sensors. Afaik only Brazil regulators insisted of telling pilots of MCAS existence (though I don't know whether the implications where clear to pilots).

raxxorrax 7y ago

I am surprised these mechanisms come in optional packages. What else do I have to order separately? Wings, engines, ruder? Is this some kind of airplane DLC and can I get the season pass for less money?

jrochkind1 7y ago

I hadn't realized planes were sold with software-only features that were only turned on if you paid more. Which is what sounds like happened, right? I guess I shouldn't be surprised, this makes sense as a money-maker, and is how software is (necessarily) sold. When you have to pay extra for certain software features, whether or not they were actually included in the binary you have as a lesser-payer, it could have been, software is intangible and has no extra per-unit cost to include the "mechanism" once developed. This makes sense as a business model for selling software, in that that's how software works. But yeah, I hadn't realized planes were sold that way. When we're talking about "features" that are pilot dashboard indicators... it really doesn't seem wise. Are there any pilot dashboard indicators that would be sold as add-ons that wouldn't increase safety were they there? I mean, what's a dashboard indicator for if not making it easier for the pilot to fly the plane? If you have to pay extra for some actual physical device, that's one thing, the physical device has to be installed. But when they're just holding back safety features with no extra per-unit cost that could simply be switched on if you paid... does not make me feel great about flying.