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Maybe this is a naive question, but why can't the automated controls on plane be designed such that: 1. They can be independently disabled? 2. For MCAS in parti

by prmph 8y ago

Maybe this is a naive question, but why can't the automated controls on plane be designed such that: 1. They can be independently disabled? 2. For MCAS in particular, disabling it will automatically revert to the previous trim level before it shuts off? 3. They can rely on sensors that are kept in enclosed storage (thus much less likely to fail due to freezing, etc) and immediately deployed when there is a problem with the usual sensors? Like the RAM air turbine? Most auto-pilot malfunctions seem to be due to sensors going bad. Edit: Sorry I wasn't clearer the first time, but I meant the enclosed redundant sensors would be brought outside when needed, and retracted when not in use. Even the pitot tube could benefit from such a scheme

Neil44 8y ago
I guess it would be the complexity of the troubleshooting procedures involved if every feature had it's own disabler. You only have a short time under high pressure to resolve these issues so I can see that fewer, broader stroke options would be better.
crocal 8y ago
Implementor of similar systems here. 1. It's possible, but you have to understand that a pilot, however bright he may be, cannot be overloaded with too many modes of operations. You can't always have Neil Armstrong driving... 2. We have to wait for the conclusions of the investigation. There is obviously still a lot of question marks about what /should/ occur and what /did/ occur, so it's difficult to speculate (at least for me) on what a correct implementation of the system should have been. 3. Each sensor has pros and cons. For an AOA, I am not an expert, but well, it's supposed to measure the lift under the wing, so I don't see how you can avoid being outdoor to get a direct measure of this quantity. I believe someone on HN more expert could give more insight here, but my experience when you try to use indirect sensors is that it générâtes the need for /more/ computational complexity to deduce the intended measure from indirect sources. For your last comment, I would complement that auto pilots malfunction due to sensors going bad /unnoticed/. We should take "going bad" very broadly: either the sensor is broken, or it is not picking up something that it should because, well, the designer just did not think about it.

by prmph 8y ago

Neil44 8y ago

I guess it would be the complexity of the troubleshooting procedures involved if every feature had it's own disabler. You only have a short time under high pressure to resolve these issues so I can see that fewer, broader stroke options would be better.

crocal 8y ago

Implementor of similar systems here. 1. It's possible, but you have to understand that a pilot, however bright he may be, cannot be overloaded with too many modes of operations. You can't always have Neil Armstrong driving... 2. We have to wait for the conclusions of the investigation. There is obviously still a lot of question marks about what /should/ occur and what /did/ occur, so it's difficult to speculate (at least for me) on what a correct implementation of the system should have been. 3. Each sensor has pros and cons. For an AOA, I am not an expert, but well, it's supposed to measure the lift under the wing, so I don't see how you can avoid being outdoor to get a direct measure of this quantity. I believe someone on HN more expert could give more insight here, but my experience when you try to use indirect sensors is that it générâtes the need for /more/ computational complexity to deduce the intended measure from indirect sources. For your last comment, I would complement that auto pilots malfunction due to sensors going bad /unnoticed/. We should take "going bad" very broadly: either the sensor is broken, or it is not picking up something that it should because, well, the designer just did not think about it.