A petition calling for WestJet CEO Gregg Saretsky's resignation has gathered more than 13,000 signatures in less than a day.

The petition, posted Thursday morning by Sum of Us, an organization promoting corporate accountability, follows sexual assault allegations made by a former flight attendant against one of the company's pilots 

Mandalena "Mandy" Lewis is suing the Calgary-based airline, claiming she was sexually assaulted by a pilot in 2010 during a layover in Hawaii. She alleges the company protected the pilot and fired her instead.

The company says it takes the allegations "very seriously" and is "committed to maintaining a safe and healthy workplace environment." None of the allegations have been proven in court. 

Emma Pullman

Emma Pullman, lead strategist for corporate accountability advocacy organization Sum of Us, is coordinating the campaign for the WestJet CEO's resignation. (CBC)

Emma Pullman, the lead strategist for Sum of Us, says corporate responsibility starts at the top.

"Ultimately, the CEO of a company creates the corporate culture of a company — the corporate culture that decides if allegations of this magnitude of sexual assault and harassment are dealt with swiftly or are swept under the rug," Pullman said. 

The website for the petition says the goal is to gather 20,000 signatures. 

"I think the fact that it's grown this big in just a few hours shows that this is an issue that a lot of people care about," she said. 

Pullman says she met Lewis last January and was shocked to hear her story. 

"When I heard her story I was really moved and we decided to work on this campaign," she said. "My heart broke for her. because there's very few women who can say they've never experienced harassment of any kind."

The campaign is also calling on WestJet shareholders, customers, and frequent flyers to identify themselves when they sign the petition to add to the pressure on the company to take action. 

WestJet says it's aware of the petition and "will not comment on allegations contained in ongoing legal proceedings."

"[We] encourage our employees to report any behavior that may violate our policies via our confidential and anonymous whistle-blower hotline or to any member of our leadership team," said the company in a written statement.

With files from Julianne Hazlewood