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> The issue involves how software on the plane checks itself to ensure it’s receiving valid data [...] when the system is initially starting up. > software rev

> The issue involves how software on the plane checks itself to ensure it’s receiving valid data [...] when the system is initially starting up. > software reviews have occurred in a special simulator used by engineers on the ground. > The problem came to light when the latest version of the software was loaded onto an actual aircraft My stomach hurts reading this! I get no confidence at all and I am scared more problems will be found or more accidents occur. Just guessing... Someone at Boeing testing the new shiny software on a real airplane decided to mess with a sensor (AoA?) to simulate it being stuck or something and to make sure this would be properly handled. It did not work. How on earth can problems like this be found this late?

rbanffy 7y ago
I would imagine the simulators will be updated to better reflect the conditions that trigger the error on actual hardware, but it's hard to build and iterate a perfect simulation of complicated stacks like a modern jetliner.
- osivertsson 7y ago
  In a system like this the software organization should be super-confident that no matter what failures occur they will handle them gracefully. They should be this confident before even entering the sim. Getting there is hard and you should be using both models you can prove correct and hands-on "vulnerability" testing. And to make it feasible you should keep your "stack" as simple as possible. To me your comment reads like developing a system like this in a trial-and-error way until you get a pass from the sim would be OK. It is most definitely not OK.
  - rbanffy 7y ago
    Of course you don't start from a crude simulation, but when the sim diverges from real hardware behavior, you need to find the reason and update the sim to reflect real world.
- bdavis__ 7y ago
  the avionics software process has a lot of iteration in it, because of the nature of software. it all starts with a very detailed requirements phase, where what the software is going to do is written down, modeled, and reviewed. design, code, unit test. some iteration here to remove the defects. then it goes into a software test environment that replicates part (or a lot) of the system. There would be a 'software' AOA vane that would be set to replicate different conditions. (running actual A/C hardware for processor and OS) written test procedures and written results from the tests. the it would go on an airplane for specific tests. safe and simple first, becoming more complex. my experience is every problem seen in the air can be replicated in the on ground development simulator (SIL- Systems Integration Lab). Every one once the conditions are determined.
kayfox 7y ago
I think the issue is that they have now changed this risk classification of a number of systems and now have to think of stuff like "well, if the variable tag gets bit flipped, what should happen?" Its not really a sign that they are finding things that were uncertifiable before, its that they are uncertifiable post-grounding. I would honestly expect more of this to happen throughout the industry, since the FAA doesn't want to be blamed for anything, they are going to expect lots more to be spent on making even safer aircraft.

rbanffy 7y ago

I would imagine the simulators will be updated to better reflect the conditions that trigger the error on actual hardware, but it's hard to build and iterate a perfect simulation of complicated stacks like a modern jetliner.

osivertsson 7y ago
In a system like this the software organization should be super-confident that no matter what failures occur they will handle them gracefully. They should be this confident before even entering the sim. Getting there is hard and you should be using both models you can prove correct and hands-on "vulnerability" testing. And to make it feasible you should keep your "stack" as simple as possible. To me your comment reads like developing a system like this in a trial-and-error way until you get a pass from the sim would be OK. It is most definitely not OK.
- rbanffy 7y ago
  Of course you don't start from a crude simulation, but when the sim diverges from real hardware behavior, you need to find the reason and update the sim to reflect real world.
bdavis__ 7y ago
the avionics software process has a lot of iteration in it, because of the nature of software. it all starts with a very detailed requirements phase, where what the software is going to do is written down, modeled, and reviewed. design, code, unit test. some iteration here to remove the defects. then it goes into a software test environment that replicates part (or a lot) of the system. There would be a 'software' AOA vane that would be set to replicate different conditions. (running actual A/C hardware for processor and OS) written test procedures and written results from the tests. the it would go on an airplane for specific tests. safe and simple first, becoming more complex. my experience is every problem seen in the air can be replicated in the on ground development simulator (SIL- Systems Integration Lab). Every one once the conditions are determined.

kayfox 7y ago

I think the issue is that they have now changed this risk classification of a number of systems and now have to think of stuff like "well, if the variable tag gets bit flipped, what should happen?" Its not really a sign that they are finding things that were uncertifiable before, its that they are uncertifiable post-grounding. I would honestly expect more of this to happen throughout the industry, since the FAA doesn't want to be blamed for anything, they are going to expect lots more to be spent on making even safer aircraft.