The final NTSB report on the Dec. 23, 2003, crash of a Learjet 24B near Helendale, Calif., released late last month, concluded that the probable cause was loss of control for undetermined reasons. Twenty minutes after Pavair’s Learjet N600XJ left San Bernardino County Airport in Chino, Calif., bound for Hailey, Idaho, the crew requested a return without declaring an emergency. But when the jet was descending through 23,000 feet at 10,000 fpm, they declared an emergency. It was their last transmission. Both the pilot and copilot were killed in the crash. The NTSB said that a cockpit voice recorder and a flight data recorder would have helped the investigators. “An opportunity to improve aviation safety was lost here,” said NTSB acting chairman Mark Rosenker.