NextGen is not in the field at the current time. ERAM is the current system and it still uses radar to track airplanes. I wouldn’t expect GPS control of planes for 5-10 years.
The biggest problem in our air traffic is the lack of runways and/or new airports. Nobody (understandably) wants a new airport or runway in their backyard. You can only move planes so fast through an airport infrastructure regardless of technology. There’s only so may runways and bays available to handle planes once they’re on the ground.
In addition, air traffic looks pretty much like automobile traffic. Nobody (outside of freight) flies at night and as we approach 7-8am in each time zone the planes start taking off and the skies resemble any major city’s beltway. This is repeated again at the end of the day.
