Estimate the number of aircrafts in air across the globe at this moment in time



Am trying whether test my approach to this question is correct.

  1. There are 4,416 cities in the world, of which 125 are major cities.
  2. Assume 100 top airline companies operate in 125 major cities and each with have 2 airplanes (1 boeing + 1 airbus)= 25,000
  3. Assume 80% of the remaining 4,291 cities have access to terminal and only one airline is operating in each city = 3,432
  4. Total airplane flying in the sky tight now is 25,000 + 3,432= 28,432.

Could someone help me to verify this?