Investigators from the National Transportation Safety Board say a “mayday” call was radioed from the aircraft moments before it plummeted to the ground and crashed in Warren County last month, killing both passengers.The owner of the plane, Tommy Stiles of McMinnville, and flight instructor Larry Banks of Spencer, both died in the crash. The reason for the crash remains under investigation and a final report on what caused the accident will not be available for about 18 months. However, in a preliminary report filed by the NTSB, investigator in charge Heidi Kemner revealed a mayday call was made to the tracking station in Memphis, meaning the occupants knew they were in desperate straits moments before the crash.“The radar target reached 5,000 feet and turned,” Kemner said in her report.