The commissionaires at the airport protested Tuesday, saying their employer is trying to take away federal overtime benefits. (CBC)

The Halifax Stanfield International Airport was the site of another Nova Scotia contract dispute as commissionaires gathered to send the message to their employer that they want to be back at the bargaining table.

The Public Service Alliance of Canada (PSAC) local 85100 has been without a collective agreement since January 2011, according to officials, and haven't been at the table with the employer since the Commissionaires Nova Scotia made its last offer in January.

The union voted 90 per cent in favour of a strike.

A key issue is whether Public Service Alliance of Canada (PSAC) unionized members are entitled to overtime the Federal Court of Canada ordered last year.

David Crouse worked at the airport as a commissionaire from 2007 to 2010, and argued that since the Halifax airport is a federal workplace, he was entitled to the benefits of the Canada Labour Code, which offers more statutory holidays.

Until he fought it, commissionaires had been paid under less generous provincial labour standards.

While the corporation has complied, it is still trying to overturn the decision.

The union alleges in addition to challenging that court decision, Commissionaires Nova Scotia (CNS) is also trying to bargain away at the negotiation table.

"This employer [is] doing an end-run around a federal court decision by trying to force a settlement at the bargaining table that is significantly less than required by labour standards," said Jeannie Baldwin, PSAC regional vice president, in a news release.

"Today we're sending the message to the employer that we want to be back at the table. Enough is enough," Baldwin told CBC News.

"We started getting paid for those holidays last year, but the back pay they still owe us — there's been nothing. It's still in the courts. They keep appealing," said Miles States, president of local 85100.

"They are now going to take this to the Supreme Court — that's what the issue is," Baldwin said.

CNS said even if there is a strike, it will try to maintain staffing at the airport.

"We'll continue the services as the contract with HIAA is, and we'll do everything possible to make sure we meet those obligations, whether or not there is job action," said Mike Brownlow, CEO of CNS.

CNS said it's prepared to pay its commissionaires fairly and the union said it's been offered seven per cent wage increase over three years.

Both sides are awaiting a federal decision that will clear the way for a 72-hour strike countdown.