Jens Flottau Frankfurt and Graham Warwick Washington

Bombardier has always claimed it does not want to compete directly with Airbus and Boeing. But the recent stretch of the CS300 to allow for 160 seats does exactly that.

Late in development, Bombardier has extended the fuselage of the larger CS300 by 2 ft., adding a seat row—five passengers—to the baseline version. The addition of an optional second pair of over-wing exits, reduction of the seat pitch to 28 in. from 32 and use of slimline seats boosts maximum capacity to 160 passengers. The first announced customer is Air Baltic, with 10 CS300s on order and options for 10 more.

Growth from the CS300's previous capacity limit of 149 seats takes the larger version of the CSeries into Airbus and Boeing territory above 150 seats. Low-cost carriers such as EasyJet operate the Airbus A319 in a 156-seat configuration already, and the A320 is typically equipped with up to 180 seats in that segment. While Bombardier seems to hope that the extra capacity will be more attractive to a broader base of potential customers, others remain unconvinced.

One open question is whether the move up means Bombardier is indirectly conceding that the 100-149-seat niche is not big enough. Historically, all manufacturers have had difficulties building efficient aircraft in the small narrowbody segment. But Bombardier has argued that was because, unlike the CSeries, previous aircraft were shortened derivatives not optimized for the niche.

Influential voices continue to express skepticism about the prospects of the CSeries. “It's an aircraft that is attractive from a design point of view, and in terms of its operating economics, but there are a couple of factors that have hindered sales,” says Air Lease Corp. CEO Steven Udvar-Hazy.

At the Istat Americas 2013 conference in Orlando, Fla., Udvar-Hazy told Aviation Week, “it is not a family of aircraft,” and its better fuel burn will be offset by the infrastructure costs of supporting new avionics, engines and other systems. Moreover, lease rates for existing aircraft have dropped since the program's launch. “Today, you can get 6-7-year-old A319s at less than half the monthly rate of a new CSeries,” he said. “So we have an aircraft that overall is not probably where it needs to be.”

And when it comes to campaigns for new aircraft, Airbus and Boeing have made it clear that they are willing to use pricing as a tool to keep Bombardier away from their customer base. Some airlines are prepared to purchase older technology if the pricing is right, as evidenced by the likely announcement next week of a Ryanair order for 200 Boeing 737NGs for which the carrier is believed to have secured discounts well in excess of 50% over list prices. At such rates, the economic case even for the latest-generation 737 MAX is difficult to make, let alone for a much smaller aircraft. Delta Air Lines recently agreed to lease AirTran Airways' entire fleet of 117-seat Boeing 717s from parent Southwest Airlines in a deal that Delta CEO Richard Anderson described as too good to walk away from. Bombardier has hoped to sell the CSeries to Delta.