Hi QF5,
It's not a subject in particular (indeed my recollection of the Australian ATPL syllabus does not even look at spherical trig at a mathematical level).
I happen to have an interest in the concept, and at the latitudes I fly it is extremely relevant. The logistics of flying in my part of the world are huge - and quite often we fly in drums of fuel to midway points to be able to get to our desitination and return. Luckily we can land almost anywhere, hence my thought of trying to find a point central to two destinations.
Good luck with your studies.
CS