U.S. National Transportation Safety Board investigators are saying that an air medical helicopter that crashed in South Carolina on Sept. 25 did not have safety features recommended by experts. Three people—pilot Patrick Walters, 45, flight nurse Diana Conner, 42, and paramedic Randolph Claxton Dove, 39—died in the crash, which occurred at around 11:30 p.m. near Georgetown, S.C. While NTSB’s investigation is ongoing, weather has been identified as a factor. Board Member Robert Sumwalt noted that the Eurocopter AS350-B2, which had just dropped off a patient at a Charleston hospital, was flying through two severe thunderstorms when it went down. “There is nothing we have found so far to indicate there was anything wrong with the aircraft prior to the accident,” said Peter Knudson, NTSB spokesman, adding that the helicopter did not have a flight voice recorder. The crash happened one day after the NTSB published a series of recommendations designed to improve air EMS safety.