United Airlines has taken delivery of its first Boeing 737 Max 9, marking the stretched Max variant's debut at a US carrier.

The aircraft (MSN 43430) was handed over to the Chicago-based airline at Boeing's Seattle delivery centre today, United says.

The 737-9 is adorned with the special swoosh livery it has on its Boeing 787 fleet, a decision it says was driven by the aircraft's fuel efficiency.

United 737 Max 9 640

Doug Alder/Boeing

"In honour of this more eco-friendly aircraft, United has given the Max a new livery… so that employees and customers can easily recognise the plane and its superior fuel efficiency," the airline says.

The 737 Max 8, which is the baseline variant for the Max family, is 14% more fuel efficient than the 737-800, according to Boeing.

United will debut the 737-9 from its Houston Intercontinental and Los Angeles bases in June. Service is scheduled to begin from to Anchorage, Austin, Fort Laudedale, Orlando and San Diego from the former on 7 June.

The carrier configures its 737-9s with 179 seats, the same as on its 737-900ERs.

United has firm orders for 60 more 737-9s and 100 737 Max 10s, its fleet plan shows. American Airlines and Southwest Airlines introduced the 737 Max 8 in 2017.

Source: Cirium Dashboard