coming or going?

We hear it all day long. From 6am to 10pm, the sound of flight in the day or night skies over Key West. Single engine props, turbo props and jets - mostly commercial and sometimes navy.

I think the reason the sound is so much more noticeable here than in London, Warsaw or New York, is that "normal" island life is much more quiet and wherever you live on this rock, the airport is less than a few miles away. So when, every hour on the half hour (or whatever the schedule is), a plane of some sort comes flying by it'll get my attention and I'll sometimes play a little head game with myself to try to figure out whether the sound is in-coming or out-going.

I imagine there are a few clues to consider. . .
The direction of the of the sound in relation to the wind, the rolling echo of the engines on the ocean or gulf (especially from the navy jets) and the length and loudness of the doppler effect.

Of course I never really know for sure but it's a little exercise for the brain and a somehow comforting reminder that, whatever else I'm doing as I live through this life, I'm at least still paying attention.