Delta Air Lines Inc. expects deliveries of its Boeing Co. 737 Max 10 aircraft could be pushed out to as late as 2027 as the troubled planemaker undergoes federal safety and criminal reviews.

Delta has orders for 100 Max 10 planes and options to purchase 30 more, and had expected to begin receiving the planes next year.

“We were already anticipating if it came in ’25, it’d be late in the year,” Chief Executive Officer Ed Bastian said of the Max 10 in an interview Sunday in Austin. “My guess is it will be another year or two beyond that.”

Delta planned to use the largest Max model — ordered in July 2022 — within its domestic network. The airline has been taking Airbus SE A321neo single-aisle planes, and “we’re very pleased with that aircraft,” Bastian said. 

Boeing is facing a rigorous review from federal aviation regulators after a series of incidents, including the blowout of a fuselage section during an Alaska Airlines flight in January. The Alaska incident has also triggered a criminal investigation by the Justice Department. Amid those issues, federal certification of the Max 7 and Max 10 models has been delayed.

United Airlines Holdings Inc. earlier this year pulled the Max 10 from its fleet plan because of the extended delays and has been in talks to switch to another Max variant or try to secure production slots for planes from Airbus. Since Delta hasn’t taken the Max yet, “it’s not an integral part of our fleet,” Bastian said. “It’s a nice part of our strategy but it’s not an integral part.”

Delta is “comfortable” with protections it negotiated against possible delays in its contract to buy the Max 10, Bastian said, declining to be more specific. There are “several issues with the Boeing 737 Max “that need to be addressed,” and the carrier is in ongoing discussions with Boeing, he said.

Demand for travel during spring school breaks and summer remains robust, both in the US and international markets, with Delta having some of the strongest sales days in its history over the past 10 weeks, Bastian said.