The federal government is finally beginning to take over the job of comparing U.S. airline passengers against its terrorist watchlist, more than six years after it announced its post-9/11 plans to relieve airlines of that duty. Now four unnamed small airlines are uploading passenger lists to the Transportation Security Administration for comparison against the approximately 16,000 names on the TSA’s two watchlists, the agency announced this week. The rest of the nation’s airlines will continue to compare passenger names themselves using the lists provided to them by the feds, until they too switch to the new method in the coming months and years. The program, known as Secure Flight , will require all passengers to provide more information when booking a flight, including their date of birth and gender. Seventy-two hours before a flight, airlines begin sending that information to the TSA, which compares the data against lists of people suspected of being threats to aviation. The TSA then notes each person as a match, no-match or unsure. Those that match either cannot fly or get extra screening, the no-matches are allowed to print boarding passes at home and via kiosks, while the unsures must clear their names at the airline counter. The TSA is withholding the name of the test airlines for murky “security reasons” — likely a code word for bad publicity ,