Question: has any software malfunctioned?

Steve Williams answered on 12 Mar 2018:

Yes software failures are common. You will probably have noticed your own computer or phone doing unexpected things, that will be as a result of a software “bug”. Where software is critical to human safety such as on airliners there will 3 completely different sets of software produced by three different companies. The idea is that whenever the pilot or autopilot changes the controls all three systems take the input and decide how to respond. These 3 responses are compared and if there are differences between the systems then the two decisions that are the same are used. Its a kind of voting system. It doesn’t seem to matter how much you test a software system you can never be 100% certain it doesn’t contain any bugs.