AeroBD | The AERO news Company…: With Delta deal, Canadian company hopes to gain ground in single-aisle jet market For nearly two decades, Boeing Co. and Airbus Group SE have enjoyed a near duopoly making the narrowbody airplanes that have become the workhorses of the global airline industry.

A key order for Bombardier Inc.’s CSeries jets last week by Delta Air Lines Inc. just cracked opened the door for a third player. Carriers have long hoped for an alternative that could inject more competition into the single-aisle jet market, dominated by Boeing’s 737 and Airbus’ A320. Bombardier’s CSeries program promises big fuel-efficiency gains, and has won smaller commitments, including from the Swiss International Air Lines subsidiary of Deutsche Lufthansa AG. It starts flying passengers with the new jet in July.

After years of cost overruns and delays, the order from Delta, the No. 2 U.S. carrier behind American Airlines Group Inc., has bestowed a measure of street credibility on the fledgling jet. That could translate into more orders. “We are seeing some significant orders” for the CSeries, said Willie Walsh, chief executive of British Airways parent International Consolidated Airlines Group SA, after the Delta deal. “I think that will make a difference and give confidence to others to look at the aircraft.”

Mr. Walsh said there is “plenty of scope in our future plans” to consider CSeries planes in IAG’s fleet. The Delta order, announced on Thursday, is a victory for Montreal-based Bombardier, which has written off $3.2 billion on the CSeries program. The Quebec government in October stepped in with a $1 billion bailout, taking a 49% stake in the CSeries program.

For Boeing and Airbus, the Delta deal suddenly makes the CSeries a more legitimate challenger in the narrowbody market. Delta purchased the smaller CS100 plane, which doesn’t compete directly with Airbus and Boeing models. But the airline said it might switch to the larger CS300, which does.

Bombardier has now secured 325 firm orders for its 100-seat CS100 and 130-seat CS300 planes. The company is also waiting for another commitment to buy 45 jets from Air Canada Inc. to be finalized. “The CSeries is a credible threat that is here to stay,” said Bank of America analyst Ron Epstein. Bombardier still faces an uphill battle. Boeing and Airbus, the world’s No. 1 and No. 2 plane makers by deliveries, respectively, are cranking out far more 737s and A320s, both of which have been in production for decades. That allows them to win big concessions from suppliers, which can translate into discounts for airlines that Bombardier may find hard to match over the long-term.

Airbus and Boeing each plan to build around 690 single-aisle planes a year by decade’s end. Bombardier plans to build around 80 planes. Airbus won its own order of 37 jets from Delta this past Friday. “Delta got a great deal on a nice little aircraft,” said John Leahy, Airbus chief operating officer for customers, referring to the CS100 order. He said he had “doubts about a business model that requires a $500 million loss provision.”

Bombardier announced the provision alongside the Delta deal last week. It said the provision took into account the sales price and the production costs. Bombardier said such provisions are typical meeting early orders for a new jet. Boeing’s chief salesman, John Wojick, said the company doesn’t compete against the CS100 with new planes and pointed to the $500 million charge that Bombardier took as raising questions about the plane’s business case as well.

After Boeing merged with McDonnell Douglas in 1997, it competed almost exclusively with Airbus for narrowbody planes. Boeing has sold thousands of its 737s. Airbus competes with its equally popular A320. The two models—flown mostly on short- and medium-haul routes—have become both the backbone of commercial aviation and the cash cows for the two plane makers.

Boeing and Airbus have long made clear they wouldn’t make it easy for new competition. Airbus promised an “aggressive response” to Bombardier when it started the CSeries program in 2008. Airbus in 2010 unveiled plans for the A320neo, for “new engine option,” a more fuel-efficient version of the model. It is currently developing the A319neo, the smallest of the A320neo family, which will compete directly with the CS300.

At first, Boeing said airlines wouldn’t embrace the smaller CSeries. But out of concern for losing ground to its European rival, Boeing followed Airbus in 2011 with the 737 Max, a more efficient family of jets. The 737 Max 7, the direct CS300 competitor, enters service in 2019, but Boeing is reconsidering that jet’s design to sharpen competition to Bombardier.

When Bombardier salespeople last year targeted Chicago-based United Continental Holdings Inc.—the No. 3 carrier in the U.S.—Boeing, also based in Chicago, countered with a big discount for its own 737 jets.