Latvia’s Air Baltic has agreed to become the launch customer for a high-density version of the Bombardier CSeries CS300 capable of carrying 160 seats, Bombardier announced Thursday during an official unveiling of the airplane’s first flight test vehicle (FTV1) at its factory in Mirabel, Quebec. Air Baltic has chosen a 148-seat version of the larger of the pair of CSeries narrowbodies, stretched two feet beyond its original specified length of 125 feet to accommodate the extra capacity. Air Baltic holds a firm order for 10 CS300s and purchase rights on another 10.

In an interview with AIN following the announcement, CSeries program head Rob Dewar explained that Bombardier added the extra length to the center fuselage section, the only part of the CS300’s aluminum-lithium barrel that doesn’t use part numbers common to the CS100. However, said Dewar, Bombardier also needed to apply some of the modifications needed for the CS300 to the CS100, thereby contributing to its six-month delay. Other changes include the addition of a pair of over-wing emergency exit doors to satisfy certification requirements associated with the capacity addition. Previously expected to fly the CS100 by the end of last year, Bombardier consequently moved the target to the end of June, therefore delaying certification until mid-2014.