Originally Posted by
DesertNomad
A quick Google shows about 9000 Boeing commercial aircraft in service and 5100 from Airbus. So 14,100 airplanes, and I am going to guess that 75% of them are in the air at any given time and that each holds an average of 150 people.
75% is way too high. Airlines try to have longhaul a/c utilised for passenger service more than 12 hours a day on average (some airlines don't even manage that due to curfews, timezones, a/c mothballed or parked up for many hours at hub due to downturn). Shorthaul a/c generally have even lower utilisation - there are only so many short overnight flights that can be done in most parts of the world.
Not all a/c are boeing/airbus. Plenty of regional jets and prop a/c.