A journey in search of applied knowledge.
I think that this definition makes some sense, at least it's generic enough.
The canonical field trip is where you get a bunch of school children together, herd them onto a bus, and take them to the local museum of natural history. More generally, field trips are intended to provide some additional context for information gathered from mere textbooks or mentors.
Thinking back, field trips were something I really looked forward to in elementary school. It would be super cool if my employer would sponsor one. We could pack into a bus and head off to the local aquarium, or something. It would be tough to make a business case, I suppose. Feh.