Closest guess without going over wins.
Have you ever wondered, looking up at the sky, how many planes are in the sky at any given moment? We certainly have.
Aviation data companies like FlightAware keep track of all (or at least most) of the aircraft in our skies. And according to them, in the past year there were an average of 9,728 planes — carrying 1,270,406 people — in the sky at any given time.
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The lightest day for air traffic was the start of the new year, Jan. 1, 2017, when — at the day's peak — there were 3,354 planes in the sky at the same time.
And the heaviest air traffic day was Aug. 5, 2016, when 12,856 planes carrying 1,590,929 people were sky-bound at the same moment.
FlightAware uses navigation data from countries around the world, both through military and government agencies, in addition to using radar data through a global network of antennas that track airplanes overhead. The company calculated how many planes and passengers were in the sky at any given moment by looking at scheduled flights from June 1, 2016 through May 31, 2017.
Scheduled flights don’t account for cancelations or delays, however they potentially provide more accurate information, as radar tracking is not possible above large bodies of water or on polar routes, according to FlightAware senior aviation data analyst Ryan Jorgenson.