Air Canada has been plagued with labour troubles over the last year.
The airline and its pilots and mechanics have been in a bitter contract feud that prompted the federal government to step in earlier this month. Ottawa has also had to intervene in contract disputes involving the airline's flight attendants and its customer service agents.
"Whether or not he's in Canada, I don't think he'd be here anyway, but it's symbolic. This is the man who controls the country and this is the man who needs to hear our message, so hopefully things will start to change," said Ryan Wick, a union executive with the International Association of Aerospace Workers and Machinists.
Wick, holding a sign that read "Lisa Raitt shouldn't work for Air Canada," was one of about 25 protesters who gathered despite the wet snow that fell around them.
"We've had our rights taken away to collectively bargain and I believe we have a government who is trying to union bust in this country," added Wick. "I don't think it's fair and I don't think it's right. We're here for everyone in Canada."
One of the protesters went to Harper's second-floor office and knocked on the door. No one answered.
Wick admitted he is concerned that public support for Air Canada's unions may be dropping because of the number of contract disputes and a disruption in air service.
"I guess the public just sees it as every six months Air Canada's going on strike," Wick said.
"What I don't think the Canadian public understands is that there's five bargaining units within Air Canada and I think it was slyly timed by the company so that it all happens in these increments."