WestJet pilots could walk off the job as early as May 19 after voting 91 per cent in favour of striking.

The pilots and airline are still at the negotiating table, but the union now has a strike mandate after voting ended Thursday morning with 95 per cent of members casting a ballot.

The union said it still hopes to sign a contract before taking any job action, although it said large gaps exist in negotiating compensation, working conditions and job security. Negotiations resume next week in Halifax.

As a gesture of goodwill, the union said it has told the airline it will not strike during the busy May Long Weekend.

"It's clear WestJet pilots are ready to stand up for the fair contract we deserve — one that puts us in line with our peers across the industry," said Rob McFadyen, chair of WestJet's Air Line Pilots Association (ALPA) master executive council, in a statement.

"Our pilots have built this airline, and now it is time for our efforts to be properly recognized in terms of industry-standard compensation and working conditions, and real job security that prevents management from outsourcing our jobs," he said.

WestJet pilots lined up in front of the airline's head office on Tuesday. (Kyle Bakx/CBC) Negotiations for a new contract began in the fall and the lack of progress toward a contract resulted in a strike vote two weeks ago.

WestJet is working on contingency plans in case of job action, although executives won't provide any details.

"We respect the outcome of this vote and recognize the mandate WestJet pilots have given ALPA," said Ed Sims, WestJet chief executive, in a statement. "We are certain our guests will appreciate that this update confirms their travel will be unaffected over the Victoria Day long weekend."

The threat of a strike is already hurting ticket sales at the airline, as Sims told journalists earlier this week "we're seeing a degree of anxiety from our potential guests."

WestJet CEO Ed Sims says the airline is making contingency plans in case of a pilot strike. (Kyle Bakx/CBC) "I have almost a visceral reaction to the concept of 70,000 WestJet guests potentially being stranded, 740 flights being disrupted," he added.

Nearly 150 pilots from WestJet and other airlines demonstrated outside the company's annual meeting with shareholders outside its Calgary headquarters on Tuesday.

"What we're doing, just to be on the safe side, is making alternate suggestions if people are travelling in the next 10 days or so," said Sandra Tompkins, a travel agent with TierOne Travel in Calgary. "With WestJet, I have faith that they will pull it together before a strike happens. That's what we're hoping, anyway."

Federal Transport Minister Marc Garneau said he is watching the negotiations closely.

"We will wait and see what happens," said Garneau in Ottawa on Thursday. "Obviously we would like, hopefully, for both sides to come to an agreement, but we must give that process a chance to occur."

The biggest sticking point in negotiations is whether pilots for WestJet's new discount airline Swoop, will be part of the union or not. Swoop begins flying on June 20 and is designed to be an ultra low-cost carrier. WestJet has been looking outside of Canada for Swoop pilots.

WestJet's pilots want to fly Swoop flights, however that will cause increased costs for the new airline. WestJet has said Swoop must have low operating costs for it to compete with upstart discount airlines such as Flair Airlines.

"There has to be an agreement between us and the [WestJet] executive about who is going to be flying those airplanes," David Colquhoun, with the union's negotiating team, said in an interview. "Right now there is nothing written down that says it is going to be WestJet pilots, but our pilots have overwhelmingly told us they expect to be flying those airplanes."