3 ms·

The checkbox isn’t the “smoking gun” but rather part of a broader range of system issues in design and usability that likely contributed the USS John McCain acc

• iforgotpassword 2y ago
  I think this is the actual wtf, along with the transfer ui: > The transfer of thrust comes with an additional level of complexity because the propellors must be transferred one at a time. Half way through a transfer the boat is in a situation where one propellor is controlled by one station and the other is controlled by someone else. At this moment the checkbox labeled “Gang” is automatically unchecked. Absolutely no surprise that in a moment of panic, the thrust controls end up spread across multiple stations. Why is this even a feature? Not a sailor so just armchair commenting, but in what situation would that be beneficial?
  • firesteelrain 2y ago
    From what I was able to infer this is the use case of “Splitting Thrust Control During Station Transfer” (btw I made that up just based on my reading of it. I don’t design Navy ship subsystems for a living - I work on specialized subsystems like these) The temporarily assigning control of each propeller to different stations would require the automatic deselection of a synchronization (or "Gang") function during the transfer. Why weren’t they properly trained on this? How did they get into this situation unknowingly? I would assume a provided manual by the manufacturer would have trained the Sailors on how to properly perform this function. This sounds like a more exceptional than routine use case.
    • willyt 2y ago
      I've experience of steering a twin prop 50 tonne SAR vessel so quite a bit smaller than this but still same principles. We also have strict procedures for transferring command of the helm between different stations. There is never a situation where you would want the throttles for each prop split between command stations. There is almost never a situation where you would want the throttle controls at a different station than the helm (the person steering). The throttles and the rudder interact a lot and in any close quarters manoeuvring situation you want helm and throttles all under the control of one person.
      • bbarn 2y ago
        "Never" is a strong word. I could definitely see value in war-time, if perhaps one was degraded or damaged, and required special attention that might justify having a person focused on it and communicating with the helm.
        • ARandumGuy 2y ago
          That's a good argument for independent throttle control being possible, but it's not a good argument for that being the default. When working with safety critical systems (which throttle control absolutely is), it's important to have sensible, easy to understand defaults. The more steps you have to take to do the "correct" thing, the more likely it is that someone screws up one of those steps.
          • bbarn 2y ago
            Seems to me a technically advanced enough system like this should probably combine the independent throttles with the steering to some extent? I'm talking out of my rear possibly, but like if a severe enough turn radius was used, maybe then automatically adjust the throttles to make it possible in combination with the rudder? (as a default)
            • ARandumGuy 2y ago
• jki275 2y ago
  This design dates to the 90s at least. I went to school on this system in 1997 and it wasn't new then, it was new to our class of ships but had been in service for a number of years prior. If it went through an HMI review it wasn't by anyone qualified to do it.
• Havoc 2y ago
  That just suggests the review process isn’t fit for purpose either