I don't fly aircraft but I do design systems and care a lot about the "human interface" part. Things I design won't kill anyone but will cost an awful lot of money in a split second if used incorrectly - and as such I spend a lot of my time watching and listening to people using what I design in real world situations, and forensically taking apart what happened when something goes wrong. There are a number of things that have become clear over time.
Human ability to misunderstand your design intentions or to think that the system does more than it really does - is almost unlimited.
Human ability to think that they know: that because this does X then if I use it this way it must do Y - is almost unlimited.
A designer's ability to comprehend all possible permutations of X and Y is limited. Sometimes users view of X and Y are simply illogical, but often they have a point. Sometimes what you design may be perfect in theory but just simply not the way that the world works in practice.
Human ability to quickly read a message or react to something unexpected when they are preconditioned to react in a different way is very poor.
Particularly so when they have done the same process 100 times before, seen the same error and ignored the same error 100 times , then on the 101st go you display a different error that is important. The critical stuff gets lost in the noise.
Once things start to go off-piste and the pressure is on, some individuals stop, think and analyse. For others, everything goes to rats, logical thinking goes out of the window.
Language barrier is a problem. Everything that I do is in English but a fair proportion of my users are European so not in their mother tongue. Not only do they have to mentally translate back and forth, there are cultural differences too.
Out of curiosity, are the memory items always in English? Is there any possibility of a misinterpretation between the native English and the mother tongue of whoever is actioning it - either through language or cultural issues? Could some of the subtlety that is important and "obvious" to a native speaker be lost?