Atlanta-based Delta Air Lines Inc has cancelled an order for 18 Boeing wide-body 787-8 Dreamliner jets (valued at $4 billion at list prices) — a commitment that it inherited through its 2008 merger with Northwest Airlines.

Delta reached an agreement with Boeing on the cancellation, according to a statement from the carrier. It is continuing with orders already in progress for 120 narrow-body Boeing 737-900ERs.

John Dern, a spokesman for Chicago-based Boeing, said: “We’ve been working closely with Delta, as their needs have evolved since inheriting the order from Northwest. Customer interest in the 787 continues to be strong, with almost 1,200 orders to date.”

Bob Mann, head of aviation consultancy RW Mann & Co in New York, said: “I wasn’t surprised to hear about the cancellation by Delta, but I was surprised that they took almost 10 years to do it.”

Delta last year deferred taking four Airbus A350s until 2019 and 2020, instead of 2018 as originally scheduled. It still has wide-body orders for 25 A350s and 25 smaller A330neo planes on its books.