Bombardier Inc (BBDb.TO) said on Friday it delivered its first CS300 aircraft to customer Swiss International Air Lines AG, marking a significant milestone for the Canadian planemaker's CSeries passenger jet family.

Although it has won accolades for fuel savings, the CSeries has not received a substantial order since the sale of 75 CS100 jets to Delta Air Lines nearly a year ago.

The CS300's delivery also comes as planemakers are bracing for another bout of softer sales this year after a prolonged order boom peaked in 2014.

The 130-seat CS300 is larger than Bombardier's 110-seat CS100 plane.

Its maiden commercial flight will be from Geneva to London, when it enters service on June 1, Bombardier said.

Swiss International is expected to take delivery of 30 CS300 and CS100 aircraft.

Bombardier has so far delivered 12 CSeries aircraft, nine of which were to Swiss International, the planemaker said.