10 ms·

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

by 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.
- cryptonector 7y ago
  Reminds me of that Red Dwarf episode where Rimmer wants to go to red alert and Kryten asks "are you SURE sir? it does mean changing the bulb!".
  - MaxBarraclough 7y ago
    Reminds me of a different Red Dwarf moment. Any damage? I don't know, the damage-report machine's been damaged. Apparently they played the same gag twice: https://youtu.be/1KEHSOPSvhc https://youtu.be/1KEHSOPSvhc https://youtu.be/R49IKBWznOM?t=19 https://youtu.be/R49IKBWznOM?t=19
    - cryptonector 7y ago
      Good one!
- blackflame7000 7y ago
  If you see two AoA sensors that aren't in agreement then you can safely assume either one sensor has failed or physics itself has.
  - phire 7y ago
    The 737 has AoA sensors by default, the autopilot uses them and the flight computer corrects the flight speed based on the AoA and issues stalling warnings based on the values. But the display which displays raw AoA readings to the pilots is an optional extra, only 20% of 737 maxes ship with it enabled. Normally pilots (or at least commercial pilots) are trained to fly without referencing the AoA by staying well within the safety margins. So, if the AoA isn't shown anywhere in the default configuration, there is no way for the pilots to crosscheck them and see the fault. Which is why you need the AoA disagree warning message. Unfortunately, Boeing messed up and the AoA disagree warning was only enabled on the planes with the AoA display option enabled.
azhenley 7y ago
Does a pilot know whether the particular plane has it installed or not?
- inferiorhuman 7y ago
  No, that's the point. All 737 MAX planes were supposed to have an angle of attack disagree annunciator. Boeing thought all 737 MAX planes were sold with a working angle of attack annunciator. Turns out only some of them had working warnings. Boeing discovered that the annunciator would only work under certain configurations but decided that this wasn't serious enough to notify airlines or the FAA. And then Lion Air crashed one of these managerial marvels.
  - PedroBatista 7y ago
    Indeed, the 737 MAX is a dangerous bastardized old design but a managerial marvel.
    - FabHK 7y ago
      - "We thought the 'AoA disagree' warning was functional in all jets we delivered, but turns out it works only if this other paid upgrade has been installed." - "We planned for, and certified, an MCAS operating within certain boundaries, but then delivered a plane that exceeds these limitations multiple times." - "To save money, we built a plane whose handling characteristics are so crappy that we could not certify it, unless we put in an extra system interfering with primary flight controls, but let's not tell anyone about it." - "We've added this powerful system interfering with primary flight controls, and it depends crucially on AoA data, which we receive from two sensors. Well, let's just pick one of them and ignore the other one. It'll be fine." Managerial marvel? I assume you're not sarcastic, so what do you mean?
      - PedroBatista 7y ago
        You assumed wrong, or at least half-wrong. It's a managerial "marvel" because they managed to certify and deliver that mutant flying turd adding billions to their bottom-line, earning their bonus while spending Boeing's good name and capitalize their decades-long "investment" on FAA. That's top-notch management right there...
ErikVandeWater 7y ago
I see. It is still the same problem where the pilot does not have an indication as to whether the safety feature is telling them that there is not a problem or if the safety feature is not telling them anything about the existence of a problem.

by AnssiH 7y ago

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.

cryptonector 7y ago
Reminds me of that Red Dwarf episode where Rimmer wants to go to red alert and Kryten asks "are you SURE sir? it does mean changing the bulb!".
- MaxBarraclough 7y ago
  Reminds me of a different Red Dwarf moment. Any damage? I don't know, the damage-report machine's been damaged. Apparently they played the same gag twice: https://youtu.be/1KEHSOPSvhc https://youtu.be/1KEHSOPSvhc https://youtu.be/R49IKBWznOM?t=19 https://youtu.be/R49IKBWznOM?t=19
  - cryptonector 7y ago
    Good one!
blackflame7000 7y ago
If you see two AoA sensors that aren't in agreement then you can safely assume either one sensor has failed or physics itself has.
- phire 7y ago
  The 737 has AoA sensors by default, the autopilot uses them and the flight computer corrects the flight speed based on the AoA and issues stalling warnings based on the values. But the display which displays raw AoA readings to the pilots is an optional extra, only 20% of 737 maxes ship with it enabled. Normally pilots (or at least commercial pilots) are trained to fly without referencing the AoA by staying well within the safety margins. So, if the AoA isn't shown anywhere in the default configuration, there is no way for the pilots to crosscheck them and see the fault. Which is why you need the AoA disagree warning message. Unfortunately, Boeing messed up and the AoA disagree warning was only enabled on the planes with the AoA display option enabled.

azhenley 7y ago

Does a pilot know whether the particular plane has it installed or not?

inferiorhuman 7y ago
No, that's the point. All 737 MAX planes were supposed to have an angle of attack disagree annunciator. Boeing thought all 737 MAX planes were sold with a working angle of attack annunciator. Turns out only some of them had working warnings. Boeing discovered that the annunciator would only work under certain configurations but decided that this wasn't serious enough to notify airlines or the FAA. And then Lion Air crashed one of these managerial marvels.
- PedroBatista 7y ago
  Indeed, the 737 MAX is a dangerous bastardized old design but a managerial marvel.
  - FabHK 7y ago
    - "We thought the 'AoA disagree' warning was functional in all jets we delivered, but turns out it works only if this other paid upgrade has been installed." - "We planned for, and certified, an MCAS operating within certain boundaries, but then delivered a plane that exceeds these limitations multiple times." - "To save money, we built a plane whose handling characteristics are so crappy that we could not certify it, unless we put in an extra system interfering with primary flight controls, but let's not tell anyone about it." - "We've added this powerful system interfering with primary flight controls, and it depends crucially on AoA data, which we receive from two sensors. Well, let's just pick one of them and ignore the other one. It'll be fine." Managerial marvel? I assume you're not sarcastic, so what do you mean?
    - PedroBatista 7y ago
      You assumed wrong, or at least half-wrong. It's a managerial "marvel" because they managed to certify and deliver that mutant flying turd adding billions to their bottom-line, earning their bonus while spending Boeing's good name and capitalize their decades-long "investment" on FAA. That's top-notch management right there...

ErikVandeWater 7y ago

I see. It is still the same problem where the pilot does not have an indication as to whether the safety feature is telling them that there is not a problem or if the safety feature is not telling them anything about the existence of a problem.