Air traffic control continuously lags behind the increasing volumes of military and civilian planes using air space. All major international airports and heavily used national airports are exposed to constant dangers of mid-air and ground collisions. In addition, major inter-city and inter-continental air-lanes are heavily congested. Aggravating factors are military plane manoeuvres which interfere with civil aviation, and airline economics which may result in less than optimal maintenance and equipment. The increased use of private airlines also poses a threat as inexperienced pilots inadvertently enter commercial air lanes. Justification for an expensive satellite-based plane tracking system over the Atlantic included the possibility of still greater air traffic density.
Air traffic congestion causes unnecessary and excess fuel usage and associated air pollution, and noise pollution, especially near airports.
Every year hundreds of near-miss collisions are reported, many at the more than 25 major world airports which each serves between 5 and 30 million passengers annually. Congestion-caused waiting times often extend to hours at major airports, and fuel is wasted by airplanes maintaining circular patterns, stacked above the runways. British Airways estimates that it burns some 63,000 tonnes of fuel a year because of air traffic delays over Heathrow and Gatwick airports alone.
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.