The union representing striking airport workers says a temporary structure near the runway that was damaged in a storm last summer poses a risk to passenger safety.

A storm on July 20, 2016 ripped pieces of fabric off the tent-like building used as a screening facility for vehicles moving into the restricted area.

The storm blew pieces of fabric onto the runway, said Marianne Hladun, regional executive vice-president for the Prairies with the Public Service Alliance of Canada.

"Anyone who's aware of airport safety knows that you don't want that stuff on the runway," she said.

The union also says the Winnipeg Airport Authority doesn't have an occupancy permit from the City of Winnipeg. "So in my mind there should be no one in there," said Hladun.

A spokesperson for the Winnipeg Airport Authority dismissed the union's claims, saying a structural engineer inspected the structure the day after the storm and declared it safe.

"I think the union is trying to use fear tactics like this to leverage more financial windfall for their members in the negotiation process," said Tyler MacAfee, spokesperson for the WAA.

Since the federal government has jurisdiction over the land at the airport, MacAfee said the authority doesn't need to get an occupancy permit in order to have the building there. Still, the WAA is voluntarily going through the city's permit process, MacAfee said.

The authority gave the city notice in February that it wanted to keep the structure there for another 32 months. That process is ongoing, MacAfee said.

He also said the union is not responsible for ensuring the safe operation of the airport. That responsibility rests with the authority and Transport Canada, he said.

"I understand the tactic that's being used by the union in this case, but the union is not the expert in this. The airport authority, and the management of the airport authority, is the expert on this. And the oversight on this is Transport Canada. So the expert and the oversight is both saying this facility is fine."

About 150 airport employees, including duty managers, administrative workers, tradespeople, IT workers, airfield maintenance personnel and labourers, went on strike on July 24, after negotiations with a federally appointed mediator broke down.

Both the WAA and the union accuse the other of walking away from the negotiating table.

MacAfee said Saturday that the two sides remain far apart in negotiations. He said the union has requested 5.5 per cent increases in two years of a two-year contract, in addition to pension, vacation and other concessions. 

The workers, who are also represented by the Union of Canadian Transportation Employees, have been in negotiations since last October and without a contract since June 30, 2016.

With files from Kelly Malone