Tense and adrenalin-filled passengers moved children away from an American man accused of endangering an aircraft, witnesses told his trial in the North today.
An agitated Jeremiah Mathis Thede alarmed parents during a transatlantic flight which had to be aborted, cabin crew alleged.
The United Airlines aircraft diverted to Belfast after flight attendants became worried by the "odd" behaviour of the accused after he demanded crackers.
Cabin steward Carlos Pagan told Antrim Crown Court: "There was tension, people were nervous, I felt people being nervous and kind of looking around, what was going on, and also I would say adrenalin was high as there were families with kids, the fathers were protective."
The Boeing 777, carrying 264 passengers, was en route from Rome to Chicago on June 20 last year when the captain made the decision to touch down at Belfast International Airport after concerns were raised about Thede's behaviour.
The Californian, 42, denies a charge of endangering an aircraft or persons in the aircraft.
Mr Pagan said the accused approached crew while they were preparing for take off to demand crackers.
"We felt that it was odd, the way he asked us for the crackers."
He went on to stand in the aisle, looking for something in his bags and went into the lavatory repeatedly.
Mr Pagan added: "I heard a guy told him to cut it off and he said 'I am not afraid of you', meaning I will do whatever I want, I am not afraid of you."
Thede, dressed in a light grey suit and white shirt, sat in the dock listening as United staff gave evidence to the jury. He has been on bail in Northern Ireland awaiting trial since last June.
Sheila Wire, the purser in charge of the flight crew, said she had received a series of complaints from passengers before advising the pilot to ground the aircraft.
"I was concerned that they were so concerned."
Passengers had approached her discreetly. No evidence was given from them about what had prompted their concerns.
Ms Wire put male stewards in the aisle serving the accused after she said he pursued a stewardess who had to almost sprint away.
"The mothers moved their kids from that side. The lady behind him who had the two children, she put her children by the window."
It has been claimed the plane had to dump thousands of litres of fuel before making the unscheduled stop.
As the crew would have exceeded their legal flying hours if the aircraft had resumed the journey straight away, the passengers were forced to wait almost 24 hours before the plane could take off again, with many having to sleep on the terminal floor.
The trial continues.