An economics professor who was flying from Pennsylvania to Canada to give a speech, was pulled off a plane after a passenger mistook his math writings for Arabic terror messages.
40-year-old Guido Menzio boarded an American Airlines to Ontario, where he planned to give a speech at the Queen's University.
The woman sitting next to him tried to engage him in conversation, and when he didn't respond, she noticed of his pad.
She watched the University of Pennsylvania professor scribbling Arabic, and subsequently handed over a note to a flight attendant, expressing her concern.
Menzio said that he was too focused on the mathematics to respond to the woman. The aircraft remained on the runway for an extended period of time, before the pilots took the plane back to the gate.
Airline personnel boarded the plane and asked the professor to step out. Menzio was questioned by an agent, who told him that he was being suspected of terrorism.
He was ultimately considered not a credible threat after showing him his note pad, which contained mathematical writings.