Airbus got a boost for its largest twin-engined jet on Tuesday when Qatar Airways said it was considering upgrading some of its A350 orders to the largest model as it took delivery of the first such plane.

The A350-1000 is designed to seat 366 people and competes head-to-head with Boeing's profitable 777. The first A350-1000 was handed over to the Gulf carrier on Tuesday, joining the smaller A350-900, which has been in service for three years.

Airbus says the lightweight A350-1000 is 25 percent more efficient than the most popular current version of the 777, the 777-300ER.

But sales of the 777-300ER have picked up, and Boeing is working on plans to leapfrog the A350-1000 with an upgraded 777X boasting over 400 seats.

Boeing last year sold 32 777-300ERs against just one order for the A350-1000. Some airlines have begun downgrading some A350-1000 orders to the 325-seat A350-900.