A fellow passenger thought the math equations he was writing might be a sign he was a terrorist.

SF Gate reports.

Professor’s airplane math didn’t equal airplane threat

PHILADELPHIA (AP) — An Ivy League professor said his flight was delayed because a fellow passenger thought the math equations he was writing might be a sign he was a terrorist.

American Airlines confirms that the woman expressed suspicions about University of Pennsylvania economics professor Guido Menzio. She said she was too ill to take the Air Wisconsin-operated flight.

Menzio said he was flying from Philadelphia to Syracuse on Thursday night and was solving a differential equation related to a speech he was set to give at Queen’s University in Ontario, Canada. He said the woman sitting next to him passed a note to a flight attendant and the plane headed back to the gate. Menzio, who is Italian and has curly, dark hair, said the pilot then asked for a word and he was questioned by an official.