A bombshell was dropped Monday in Canada’s aviation industry, with Westjet announcing it would be sold to private equity firm Onex Corporation.

“Since our first flight in 1996, WestJet has been singularly focused on providing better options for the Canadian travelling public and this transaction retains that commitment,” said Clive Beddoe, WestJet’s Founder and Chairman in a statement. “I am particularly pleased that WestJet will remain headquartered in Calgary and will continue to build on the success that our 14,000 WestJetters have created.”

Onex will pay $31 per share for Westjet, making the deal worth $5 billion. It will then take Westjet off the stock exchange to operated as a private company, meaning it will not have to report information it now routinely shares on the health of its routes and overall services. At the moment, Flair is Canada’s only other private airline.

Westjet is in the midst of a transformation from a folksy, point-to-point low-cost carrier to a globally competitive carrier that caters to the premium market. It recently launched 787 Dreamliner services from its Calgary hub to London, England, to be followed by Dublin and Paris.

Its subsidiary, Swoop, was created as a backstop on the lower end of the market. Details on Swoop’s future were not released.

This is not the first time Onex has tried to enter Canada’s aviation market. In 1999, Onex made a controversial – and ultimately unsuccessful – bid to buy Air Canada and merge it with Canadian Airlines International. Though the deal was blocked, Canadian would eventually merge with its larger rival as it withered under staggering debt loads.

“WestJet is one of Canada’s strongest brands,” said Tawfiq Popatia, a Managing Director at Onex. “WestJet is renowned internationally for its unparalleled guest experience and employee culture. We’re thrilled to be partnering with WestJetters and continuing this remarkable Canadian success story.”

Westjet recently signed a joint venture agreement with U.S. carrier Delta Air Lines, inaugurating Calgary-Atlanta service to deepen the partnership. The deal is awaiting regulatory and government approvals. It plans to launch similar discussions with trans-Atlantic partners Air France-KLM in the coming months.

Onex is paying a 67% premium over Westjet’s closing share price on Friday to complete the all-cash deal.

Westjet said it was approached in March about the deal. Montreal-based Air Transat has also been approached by potential buyers and is reviewing its options.

“We are delighted to continue the journey of building an airline based on a growing network,” said Westjet President and CEO Ed Sims, “providing competitive airfares and more choice to, from and within Canada, for communities large and small. Integral to this relationship is a commitment to our employees, and our unique ownership-driven culture.”

The sale is contingent on shareholder, court and government approvals.