NEW YORK — Canadian airline WestJet plans to buy 65 of the new fuel-efficient 737 MAX aircraft from Boeing as it looks to modernize its fleet.

Boeing said Thursday that the pending order is valued at $6.3 billion at current list prices, although after typical discounts estimated by aircraft-valuation firm Avitas the actual value is about $3.2 billion.

The deal includes 40 737 MAX 8 planes and 25 737 MAX 7 aircraft. Deliveries are expected to start in September 2017.

The 737 MAX will have CFM International LEAP-1B engines, and is expected to reduce fuel burn and CO2 emissions by 13 percent as compared with the most fuel-efficient single-aisle aircraft currently available.

WestJet Airlines’ current fleet includes 103 Boeing next-generation 737 and four Bombardier Q400 next-generation aircraft.

Boeing currently has 737 MAX orders from five other North American airlines.