London /\/\/\/\/\/\ Paris
I thought it was a good metaphor for writing: A series of adjustments and corrections on the way to a finished piece of work.
It does of course help if you know where your final destination is. For a short story I would say it is essential because there isn't the space to make long deviations from the direct line, but a novel can be written without knowing the exact final destination, so long as you know roughly where you're heading.
So, as a writer/pilot, your job is to keep an eye on the final destination as you write, always nudging the story back towards it but being quite relaxed about not actually travelling in a straight line. Sometimes the adjustments and corrections are huge (I speak as one in mourning for 20,000 words just cut), but so long as we get there in the end, who will ever know? Only the pilot.