A Frontier flight headed to Orlando had to make an emergency landing, after things got absolutely crazy in the air.
The flight had taken off Wednesday night from NYC ... at some point, a male passenger started flipping out. An eyewitness tells TMZ ... the man accused the lady behind him of sticking him with a needle and trying to steal his DNA. He then threatened to smack everybody on the plane ... as he kept spinning conspiracy theories.
As the man yelled threats, some of the other passengers jumped him and tried restraining him. That was clearly enough for the pilot, who headed for the nearest runway, landing at the airport in Raleigh, North Carolina.
It seems the man may have been in the throes of a mental health crisis. An FBI spokesperson tells TMZ an investigation is underway. The passenger was taken off the plane. We do not know where he went or where he was taken.