However, Air Canada, which hatched its own plan to buy Canadian Airlines, made several moves to complicate the Onex bid, including adopting a poison pill created to drive up the price.
The WestJet deal isn't its first tilt at the aerospace industry: it unsuccessfully attempted to buy Air Canada in 1999 and merge it with Canadian Airlines.
According to a statement released by WestJet, the purchase price represents a 67% premium to Friday's closing share price and a 63% premium to WestJet's 20-day volume-weighted average trading price.
"WestJet frontline workers across Canada have been signing Unifor cards, showing that they want to have a voice in the company", said Unifor National President Jerry Dias.
Even before the global grounding of Boeing's 737 MAX jets in March, WestJet's earnings had slipped as it worked to contain costs as its workforce unionized and was spending money on bold growth plans to expand worldwide travel, introduce first class cabins and launch a budget carrier called Swoop.
The deal is expected to close in the latter part of this year or early next year, the company said.
Unifor will continue to stand up for frontline WestJet workers as the airline is sold to Onex Corporation, a takeover specialist with a long history of cost cutting and restructuring at the companies it buys.
But WestJet founder and chairman Clive Beddoe said the deal retained WestJet's commitment to provide better options for the Canadian traveling public. The airline has reported declining net profit for each of the last three years, hurt by rising fuel costs, pressure on ticket prices and other issues.
Analyst Benoit Poirier of Desjardins Securities said Onex might also look to acquire Transat A.T. The tour operator, which owns Air Transat, competes with WestJet for sun destinations and launched in 2017 a $750-million plan to develop a hotel chain in Mexico and the Caribbean.
Popatia said the new foreign ownership threshold - raised to 49 per cent from 25 per cent after amendments to the Canada Transportation Act - "had nothing to do with" its decision, stating that Onex Partners - the company's flagship private equity fund - is the sole equity provider.
The committee subsequently recommended the transaction to the WestJet board, who are recommending shareholders vote to accept the offer.
Completion of the transaction is subject to a number of conditions, including court, regulatory and shareholder approvals.
Taylor, the Canaccord Genuity analyst, said the Onex acquisition would not dramatically alter the competitive landscape. "In our view, a private equity owner of an airline is likely to remain rational with respect to its approach to yields and profitability vs. market share", he said in a note to clients.