There may or may not exist in a place far off, an airline company with planes that are small and susceptible to storms...
In such an airline, where they endeavor to keep flying costs low, they decide against computers and instead hire a single mathemetician to calculate their flight patterns to a working path - a distance, and some angles to turn.
Such a mathemetician needs only a calculator and a basic knowledge of the Law of Sines - and perhaps the Law of Cosines. To understand how this process works, and to earn a rather required grade for the class at hand, I invite you to see how he does his work.
The links on the right will guide you to problems...
Definition of Trig - training problem
Law of Cosines - the Line of Sight
Law of Sines - When you gotta go
Law of Both - Observer's day off