Mining patterns

What is meant when it is said that patterns are mined? For the software community, that means actually looking at code, and finding the essence across multiple implementations. But what does it mean to mine a pattern for a system level pattern? At the hightest level, the pattern may be so abstract it is meaningless. Aircraft systems, for the most part, have a fuselage, wings, tail, and landing gears (hopefully). Not very useful. But what other system level patterns can be found? What are the common missions; or sub-missions? What does it mean to document the "transport passengers" operational pattern as opposed to "perform high altitude observation" operational pattern? The differences between those two patterns will affect the decomposition of the system as it is architected. What about the "perform maintenance" operational pattern that captures that mission for the two different types of aircraft? Something to consider.