Shortly after he began interviewing retired Air Force personnel in the early 1980s, his phone started ringing - but no one would speak. Just heavy breathing.
The veteran UFO researcher began interviewing military veterans who had witnessed similar phenomena. 'They were all telling me the same thing,' he said.
It's something that any nervous traveller dreads during a long-haul flight. But severe turbulence is set to get even worse - with climate change to blame.
In the face of a catastrophic event, like a war with Iran, the US government has a playbook to keep itself running called the Continuity of Operations Plan.