By Rachelle Reinhart with contributions from Myron Kassaraba Airplane noise over Belmont increased after major changes were made to air traffic control at Logan Airport  in 2001, when the United States Congress authorized the Federal Aviation Administration (FAA) to modernize air traffic control under a program called NextGen. NextGen moved air traffic control from a radar-based system to a GPS-based area navigation system (RNAV).  RNAV allows aircraft to travel using a computer programmed with precise waypoints—designated flight path transitions—and GPS coordinates to control the plane’s flight path. Before RNAV, air traffic control instructed pilots to make turns and altitude adjustments [READ MORE]