Components of the future mainstay of the U.S. air traffic control system — the Standard Terminal Automation Replacement System (STARS) from Raytheon Co. in Lexington, Mass., has gone through successful testing for potential Year 2000 — or Y2K — problems. Early display configuration hardware and software of STARS went through testing at Raytheon`s facility in Marlborough, Mass. Initial operating sites for STARS are to be in El Paso, Texas, and Syracuse, N.Y., later this year. Much of the STARS Y2K work consisted of testing the equipment before, during, and after the year 2000 rollover date, officials say. Leaders of the Federal Aviation Administration watched as Raytheon technicians performed more than 1,300 tests and 30 discrete rollovers of Y2K date testing. FAA officials said the system passed all test steps. — J.K.