Korean Air has converted a letter of intent covering 10 CS300 airliners to a firm order, Bombardier Aerospace announced today. The transaction also includes options on 10 CS300s and purchase rights on another 10. The larger of the two CSeries models, the CS300 can hold as many as 145 passengers, assuming a seat pitch of 30 inches.

The firm order makes Korean Air the launch customer for the Pratt & Whitney PW1521G-powered CSeries in Asia. Bombardier expects to receive certification for the 110- to 125-seat CS100 in late 2013 and the CS300 roughly a year later.

The Korean Air transaction increases to 133 the number of CSeries airplanes on firm order. Other customers that have firm orders for CSeries models include Republic Airways (40 CS300s); Lufthansa Airlines (30 CS100s); Lease Corporation International Group (17 CS300s and three CS100s); Braathens Aviation (five CS100s and five CS300s); a so-called well established, unidentified airline (three CS100s); an unidentified major network carrier (10 CS100s) and an unidentified European customer (10 CS100s).