The Federal Aviation Administration says it will upgrade the technology used to get radar data to air traffic controllers directing planes to the troubled Newark, New Jersey, airport and improve staffing to alleviate the problems there. At the same time, the agency is working on a broader multibillion-dollar plan that will be announced Thursday for long-overdue upgrades to the nation's air traffic control system. A January midair collision between a passenger jet and army helicopter over Washington, D.C. ,that killed 67 people, followed by a string of other crashes and mishaps, raised alarms about aviation safety and prompted officials to reexamine the system.