At Canada's largest airport, travellers were greeted by striking workers amid modest line-ups and flight delays.
Passengers arriving at Pearson International Airport's terminal one departure area encountered picketing airline employees, many wearing their uniform blue dress shirts and red scarves and ties.
The workers paced in front of Air Canada's entrance to the terminal, waving blue CAW TCA flags in the air, but did not block access to the building.
"We love our jobs, we want to stay, but things just never go our way," they chanted.
The employees also chanted: "Rovinescu, shame on you," a reference to Calin Rovinescu, Air Canada's president.
Inside the terminal, Air Canada supervisors and outside workers brought in by the airline helped travelers.
Some 3,800 Air Canada customer service agents went on strike just after midnight EDT Tuesday after talks between their union and the airline failed to reach an agreement.
The situation was largely calm inside terminal one, with modest line-ups at counters. Many travellers had already checked in online from home and brought only carry-on luggage, as the airline had recommended.
An Air Canada message over the intercom asked passengers to use self-service check-in kiosks and said all available staff were working. The airline apologized for any inconvenience and reduced service.
Air Canada retained Garda World Security to provide staff, said Joe Gavaghan, a Garda spokesman.
Garda employees also work as airport security screeners, but Mr. Gavaghan said the staff the company is supplying different personnel to Air Canada. He declined to provide further details.
Peter Fitzpatrick, an Air Canada spokesman, said the airline had "engaged an airport service company to provide security and assist customers at self-service kiosks."
At Pearson, workers wearing white dress shirts and dark pants identified themselves as Garda employees. Some were stationed near check-in kiosks.
Several flights - both departing and arriving - were delayed, a trend that seemed to intensify during the morning rush.
Mr. Fitzpatrick characterized the waits as minor, saying there were "a very limited number of short delays".
However, he acknowledged that managers who are filling in for customer service agents "are having some teething pains."
"Obviously, this is their first day on the job as check-in agents and boarding aircraft, so I think it's totally natural and expected that they're not going to be quite as quick as somebody that's done it for all their life. But they're quickly ramping up," he said.
Union members predict that travellers will face longer lineups and wait times as the walkout goes on.
"It looks good right now," said Dawn Moreau, an Air Canada customer service agent for 34 years. "Is it going to stay this way? No."
"We're on Tuesday morning, it's probably the slowest morning of the week. You get into your afternoon shifts, you get into your evening shifts, you get into snowball effects down the line."
Many passengers said they noticed service at the counter was slower than usual, but most remained hopeful that the strike wouldn't significantly affect their travel plans.
Anna Shier, 35, of Ingersoll, Ont., said she arrived three hours early for her flight to Edmonton in case of delays.
The lineup "is more than usual from when I've been flying before, but I'm third in line, so it's moving pretty quickly," she said.
"But this is just the beginning, I think maybe as it gets longer into it, it might [cause delays]"
Olga Hassan, of Mississauga, Ont., said she checked in online to avoid any lines at Pearson.
"I won't be stuck here, I'll just walk into the gate," she said.
Jin Hu arrived late at terminal one, without knowing where to check in. It was his first time at the country's largest airport and he only found out about the strike yesterday, when his friend told him.
"But he also told me everything's going to be all right," said Mr. Hu, who was hurrying to make his 1 p.m. flight.
As working Air Canada staff walked around the airport, some in white shirts with colored arm bands, one stopped to help Mr. Hu, who was flying back for a vacation to his native Beijing. The airline worker helped the 28-year-old check in using a self-service machine.
Michele Montresor, an Italian who is in the midst of a three-week Canadian vacation, was a bit puzzled as he waited for a flight to Montreal.
"I'm a foreigner so I don't really understand why people are on strike," he said. "I hope it will be okay."
Mr. Montresor said the strike didn't seem that out of place to him, adding that strikes are an "everyday" occurrence in Italy.
Genny Osmond had been waiting at the airport since before 8 a.m. even though her flight to get her home to Gander, Newfoundland, wasn't scheduled to leave until 2:45 p.m. But arriving early was less about the strike than coming to the airport with her daughter, who had an early morning flight to Cuba.
"Hopefully I can get home," the 62-year-old said, taking a break from her knitting.
For the most part, she's keeping her flight routine the same. She'll be checking luggage despite a suggestion from the airline not to.
"I'm knitting so later on I'll put that in my suitcase and I'll check my bags," she said.
"I got my boarding pass online, but I always do," she added.
Ms. Osmond's daughter's flight was delayed by about 45 minutes and, around 11:30 a.m., she had yet to hear if her flight would be on time.
There was a visible police presence inside the terminal. One officer, who did not give his name, said Peel Regional Police had increased the number of officers on Tuesday.
With a report from Canadian Press
Jill Mahoney