The National Transportation Safety Board has released its preliminary report on the helicopter crash that killed seven people earlier this month, including billionaire and North Palm Beach resident Chris Cline.The copter crashed into the Atlantic Ocean on July 4 near Big Grand Cay, Abaco, Bahamas, just one minute after takeoff. Cline’s daughter, Kameron, and her friend, Brittney Layne Searson, also died in the crash. They graduated from the Benjamin School in 2015 and were attending college together at Louisiana State University.According to the NTSB, the helicopter was flying from Walker’s Cay Airport to Fort Lauderdale/Hollywood International Airport to obtain medical treatment for two passengers. It originally departed from Palm Beach International Airport and landed at Big Grand Cay sometime between 1:30 and 1:45 a.m.After passengers boarded at Big Grand Cay, the aircraft lifted again. A witness reports seeing it climb out about 30 to 40 feet and accelerate “while in a nose-down attitude.”A second witness, who was located about 1.6 nautical miles southwest of where the accident occurred, says he saw the helicopter lift to about 40 to 50 feet high, and then noticed blue and white lights spinning to the left between rotations, while the copter descended. He believes it rotated to the left three or four times. That witness then heard a “whoosh whoosh whoosh” sound, lost sight of the aircraft, and heard it crash into the ocean, the NTSB report says.After reporting the incident to the island’s “caregiver,” the witness went on his boat around 2:05 a.m. and used spotlights to begin searching the area where he thought the helicopter had crashed, but did not find anything.The NTSB says the Federal Aviation Administration issued an alert notice for the overdue flight on July 4 at about 3:21 p.m. Within 90 minutes, residents spotted the helicopter in 16 feet of water about 1.2 nautical miles north-northeast of where it had departed.The flight and data recorders are still being analyzed.