If you've never heard of systems engineering, you probably have some questions. If you have been a systems engineer for years, chances are you still have some questions, which you have put to one side while you get on with work. Trickier than you might think.
Aircraft have avionic systems, engine systems, airframe systems.
In fact, it seems to be one of the most over-used words in the English language. Because of the interactions, a system is complex, systems may be able to do things, to exhibit behaviour, to have system capabilities that none of their parts has. But let's not get carried away - meanwhile, back at the definition. It may appear complicated, but then it has to cover a lot of cases. Some systems, it seems, comprise a variety of different parts which fit together - a watch is a system for telling the time.