After unsuccessful drives in 2015, pilots and flight attendants at WestJet are working again to form unions at the fast-growing airline. There's one key difference this time around, though.

Last year, they were racing against the calendar as labour laws changed in June 2015 to make certification more difficult. Now the opposite is true.

The Liberal government is getting close to repealing the law that changed the way unions are formed in federally regulated industries. Soon, it will most likely be easier to form a union in Canada.

Easier, but not exactly easy.

Calgary airport refuses to run ads for flight attendants

WestJet's flight attendants group has been working for three years to form a union at the airline. After a push in the summer of 2015, it relaunched its drive this past August and is hoping to have enough cards signed by Halloween to call a vote.

The Calgary Airport Authority has declined to run this ad by the WestJet Professional Flight Attendants Association. (WPFAA)

In that effort, the WestJet Professional Flight Attendants Association raised enough money to buy ads at Calgary International Airport. They were hoping to run them at the airport, but the airport authority declined the ads.

"No reason has been given to us, to our advertising agency, to our law firm, said Daniel Kufuor, the interim treasurer for the flight attendants association. "The advertising is friendly, it is positive, it is to be paid for, just like any other client. To refuse our advertising is unfair."

In a statement to CBC News, the airport authority said it only accepts ads that showcase products and services and that advocacy ads are not permitted.

In the past, the Calgary airport has run banner ads for the Association of Professional Engineers and Geoscientists, a Calgary-based group that regulates the practice of engineering and geoscience in Alberta.

Whether airports are able to deny ads in a public building is a legal question. Canada's airports are owned by the federal government and leased to non-profit airport authorities, which operate them.

A court ruling associated with protesters at the Calgary airport resulted in the judge ruling that airports are indeed government property and subject to the Charter of Rights and Freedoms. Whether that would also apply for issues related to the relationship between employees and an employer is unclear.

Pilots turn to international union

WestJet's pilots came within five per cent of forming a union in the summer of 2015. A secret ballot vote ended with 45 per cent of pilots voting in favour of certification and 55 per cent against. However, the union drive was divisive and expensive, with the pilot's group facing multiple legal challenges from WestJet.

A year ago, the pilots who were working for a union decided to throw their support behind the Air Line Pilots Association International, an international union that represents pilots at Jazz and Air Transat, as well as many other airlines in the U.S., like United and Delta.

The association has been holding information sessions at WestJet's base cities over the past several months. It did not respond to a request for an interview.

Labour laws could be changing again

The union drive in 2015 was a race against a deadline. On June 16, 2015, labour laws changed with the passing of Bill C-525, to require a secret vote to certify a federally regulated union. Previously, auto-certification was possible, once a union had collected 50 per cent plus one employee to sign a card.

The Liberal government is in the process of repealing that law and allowing the system to revert to previous rule, meaning no secret ballot for federal employees.

Minister of Employment, Workforce Development and Labour MaryAnn Mihychuk said that the Liberals campaigned on repealing Bill C-525. She introduced Bill C-4 to that effect, which is currently on its third reading. If passed, it will head to the Senate, where the Conservative majority has suggested that it will stop the bill.

In a statement to CBC News, Mihychuk said, "Bill C-4 is fundamentally about restoring fairness, balance and stability to Canada's federal labour relations system, a critical component of our plan to strengthen the middle class and help those working hard to join it."