A transatlantic flight became a chaotic scene of cursing and assault after the plane was forced to land in St. John's, N.L., because of a medical emergency, a court hearing the case of a Toronto broadcaster accused of air rage was told Monday.

Colleen Walsh, 49, has pleaded not guilty to charges of assault, obstructing the operation of an aircraft and causing a disturbance.

The former host of the Rogers TV architecture show Structures sat in provincial court in St. John's Monday as her trial began, at times shaking her head at the testimony.

Air Canada service director Guy Marion described how the seven-hour flight from London to Toronto on March 31, 2009, was diverted to St. John's. The Boeing 767 changed course after a female passenger lost then regained consciousness, he said, describing it as "a serious medical emergency."

Marion pointed to Walsh in court, identifying her as the passenger who came forward to offer first aid to the ill woman, who had been seated near her.

"She was told that her help wasn't needed," Marion said, noting that a physician on board had already responded to his request for a doctor over the PA system.

"We had to inform her a few times to return to her seat."

Walsh slurring words, smelled of alcohol: employee

Marion said Walsh initially seemed like a happy, pleasant traveller who introduced herself to staff and described her trip to visit family in Ireland. He recalled serving her lunch and two individual-sized bottles of wine, an amount of alcohol he described as "typical" for a flight of that length.

He did not remember serving her any other alcohol.

It was when the plane landed in Newfoundland that Walsh became more unruly, Marion testified.

"You sensed that she wasn't happy with the fact that we had landed in St. John's," he told the court. "She was agitated and didn't comply with our demand that she go back and sit down."

Marion described Walsh at that point as "intoxicated" and said she slurred her words and smelled of alcohol in his direct conversations with her.

While on the tarmac during a 50-minute delay, Walsh "got into it with another passenger and started cursing," Marion told provincial court Judge Greg Brown.

"The atmosphere had changed. There were a lot of passengers involved at that point," Marion said.

"Things got out of hand."

Defence lawyer Lori Marshall asked Marion whether he ever heard Walsh directly express to him a refusal to comply with his request that she sit down.

"I think I did," Marion said.

"Well ... you didn't testify to it," Marshall replied.

Marion conceded that he was busy tending to the ill passenger and other demands as his workload became "heavy."

Accused dealt 'substantial' blow to fellow passenger, court hears

Stan Harrington, 67, was seated to the left of Walsh a few rows back.

He testified that she was the only passenger standing when a flight attendant asked her to be seated.

She did not comply, Harrington said.

"At one point, she asked the stewardess, 'Do you know what's going on? You should tell us what's going on'," Harrington told the court.

Walsh then turned to the passengers behind her to ask whether anyone had more information about how long the delay would last.

Harrington said he and at least one other passenger told Walsh to "just take your seat."

Walsh then strode toward Harrington, he testified.

"She came down the aisle rapidly toward me and hit me on the right side of the head."

Harrington said it felt like the back of her hand had struck him behind the ear.

"It was quite substantial," he said of the blow. "My head went over [to the left], and I felt a sharp pain."

Harrington said he was quiet as Walsh walked toward the back of the plane.

"I didn't say anything. I just sat there," Harrington told the court.

Marion testified that he heard about the assault from upset passengers and asked Harrington if he'd like to press charges.

"He said that he did not. He just wanted to get out [of St. John's] and keep on going at this point," Marion told the court.

Marion spoke with the captain about the incident, and Walsh was removed from the aircraft, he said. Harrington later filed a complaint with police.

Walsh's online resume says she has also worked for CBC Radio and Global TV. She is described as a communications consultant and media trainer.

Her trial is scheduled to continue Tuesday.