Delta Air Lines on Thursday confirmed it has placed a large order for the Bombardier C Series, a major boost for the program.

The announcement follows a meeting of Delta’s board of directors on Wednesday. The commitment includes firm orders for 75 aircraft and options for a further 50. It is the largest ever order placed for the C Series. 

Delta's order is for the CS100, but the airline has “certain flexibility rights” to change to the larger CS300 if needed. Delta no longer plans to introduce 20 used Embraer 190s into its mainline fleet. CS100 deliveries to Delta are to begin in the spring of 2018.

For Bombardier, the Delta order could mark the much-sought after market breakthrough for the C Series among major legacy airlines. It is the first firm order from one of the major carriers in North America – a large Air Canada commitment announced earlier this year has not yet been converted into a firm contract. "Given Delta's position as one of the world's largest and most respected airlines, this deal is a strong endorsement of the C Series as the best performing aircraft in the 100-150 passenger class,” Bombardier President and CEO Alain Bellemare said. “The addition of Delta to our marquee C Series customer list gives us tremendous momentum as we approach entry-into-service this summer.”

"Welcoming Delta Air Lines to the C Series family of operators is a watershed moment for our game-changing aircraft,” Fred Cromer, President of Bombardier Commercial Aircraft, said. “As an industry leader, Delta consistently ranks first with customers, business leaders and its peers - a benchmark for operational performance. This order is a resounding endorsement of the CS100 aircraft performance and its exceptionally low operating costs.”

"As we reshape our fleet for the future, the innovative onboard experience of the C Series is a perfect complement for the top-notch service provided every day by Delta people," Ed Bastian, Delta's incoming chief executive said. "These new aircraft are a solid investment, allowing us to take advantage of superior operating economics, network flexibility and best-in-class fuel performance."

The Delta deal follows big sales campaign losses over the past few years, including most recently at United Airlines. The airline opted for end-of-the-line Boeing 737-700s instead, which were allegedly heavily discounted. In Europe, International Airlines Group (IAG) subsidiary Vueling and low-cost carrier Easyjet chose the Airbus A320neo after also having intensively studied the C Series.

While Bombardier likes to point out that the C Series does not directly compete with Airbus and Boeing models, recent airline competitions have proven otherwise. And if the Delta order stands at the beginning of a broader trend, the civil aircraft market in the 120-150 seat category may soon no longer be the duopoly that Airbus and Boeing have become accustomed since the end of McDonnell Douglas civil aircraft production. Analysts have pointed that while Bombardier is likely to control only a small portion of the market, the two incumbents will still feel more pricing pressure for the smallest versions of their narrowbody families A320neo and 737 MAX.

The Delta order raises the C Series firm order backlog beyond the mark of 300 aircraft, which Bombardier has long described as its sales target at market entry. Swiss International Air Lines plans to take delivery of the first CS100 at the end of June and will fly the first commercial service on July 15. Lufthansa became the launch customer of the C Series in 2008 and later allocated the aircraft to its subsidiary Swiss.

The Delta decision not only adds volume to the backlog, but also much needed quality. The 250 firm purchase agreements recorded so far include close to 90 from customers such as Republic Airways (40), Odyssey Airlines (10), Iraqi Airways (five), Ilyushin Finance Corporation (32) that investors have seen as unconvincing or that have themselves raised questions about their plans to actually take delivery of the aircraft as business models like Republic’s evolved.

The added credibility of the program may help Bombardier in securing more funding from Canada’s federal government that has been negotiated for several months.