The National Air Traffic Controllers Association (NATCA) says a computer software failure at the Boston Air Route Traffic Control Center on Jan. 23 knocked out both the primary and the principal backup radar system – called DARC – used by controllers to monitor hundreds of flights over seven U.S. states and thousands of square miles of airspace over the Atlantic Ocean. The outage began at approximately 5:45 p.m. EST and lasted just over one hour. Flight delays rippled across the country as aircraft headed to Boston had to be held on the ground at their originating airports until the Boston Center airspace was back up and running normally. Flights in the air headed toward Boston Center’s airspace were barred from entering and were put into holding patterns. An additional problem was that many of the newly hired controllers and trainees at Boston Center lack the experience and training to operate the backup systems, NATCA added.