Calgary-based WestJet has struck an agreement with Boeing to purchase 10 737-800s, and defer five 737-700s scheduled for delivery between 2014 and 2015 to 2016 and 2017.

Through a separate agreement with a third-party, WestJet will sell 10 of its oldest 737-700s to a third party in 2014 and 2015. Removing these older aircraft will lower the age of WestJet's fleet by a year, it says.

WestJet operates more than 100 Boeing 737 aircraft, with the oldest 737-700s aircraft built in 2001, shows Flightglobal's Ascend Online database.

"These agreements are part of our strategy to optimise and modernise our fleet mix, which will improve CASM [cost per available seat mile], while maintaining fleet flexibility going forward," says Gregg Saretsky, WestJet's chief executive.

WestJet reported CASM of 13.84 Canadian cents (13.8 cents) in the first quarter of 2013.

Source: Air Transport Intelligence news