MINNEAPOLIS (AP) — Delta Air Lines is ordering up to 70 regional jets from Bombardier as part of a major shift in the planes it uses for hauling passengers around the U.S.

Delta announced a firm order for 40 of the CRJ900 planes on Thursday, and options for 30 more. The deal would be worth $3.29 billion at list prices if Delta exercises the options, although discounts on such a big order are common.