Air traffic congestion causes unnecessary and excess fuel usage and associated air pollution, and noise pollution, especially near airports.
In Europe the poorly organized airspace system costs governments $500 million annually, airlines $980 million a year for delays, and the economy $400 million indirectly a year. On top of that, the extra mileage, inefficient routings and altitudes and other problems resulting from complex airspace cost $1.8 billion annually. Total annual cost of inefficiencies are $4.2 billion and it is estimated to reach $31.5 billion by the year 2000.
The peak period in air transport, which used to last only a couple of weeks, lasted from three to four months in European Union in 1999. Aircraft movements totalled 26,000 per day in the EU that year. The corresponding figure for the more sparsely populated USA was 48,000.
In 1999, much of the European Union airspace was controlled by the military authorities of the various member states, who limited or even banned its use by civil aircraft. Civil aircraft were obliged, therefore, to follow more or less the same routes. Given the increase in traffic, this led to congested skies.