CHICAGO (CBS) — A Chicago woman who was among the passengers who spent a night at an airport in Northern Ireland, after their flight was diverted due to a disruptive passenger, was still scratching her head two days later.

Mary Nachman flies almost every week for business, so she’s used to delays, but this weekend’s ordeal might test even the most seasoned travelers.

United Airlines flight 971 from Rome to Chicago was diverted to Belfast on Saturday, when a male passenger began intimidating others on board. Nachman said about five police officers took him off the plane after it landed.

“There was nothing noteworthy about him. He collected his bags. He was smiling, which we all thought was a little bit odd, and they escorted him off the plane. He went cooperatively,” she said.

Nachman said the man – who was arrested after the flight landed in Northern Ireland – never yelled or said anything when he was removed from the flight. The 42-year-old man with American and Italian citizenship was charged with endangering the safety of an aircraft.

“If there had been something noticeable, people would have been ‘Oh, wow, we need to get off. Get this guy off the plane. He doesn’t’ belong here.’ We would have understood. You know, people would have figured out much earlier what was going on, but it was really relatively subdued,” she said.

Nachman said the man didn’t appear to be drunk, but did upset the passenger next to him, and was staring at others.

Authorities said, because the flight crew already had exceeded the number of hours they were allowed to work, the 269 passengers and 14 crew had to wait until Sunday to continue the flight.

Nachman, her family, and other passengers spent the night at the airport, sleeping on the floor. Nachman couldn’t sleep.

The flight to Chicago resumed a full day later, but Nachman didn’t get to Chicago, because she had to reroute to New York for another business trip.