The delivery of two more Airbus A380s takes Emirates superjumbo fleet total to 44.

The delivery of two more Airbus A380s takes Emirates superjumbo fleet total to 44.

Dubai's Emirates Airline announced it has boosted its fleet of Airbus A380s to 44 planes, taking delivery of another two of the superjumbos which went straight into service on Saturday.

"Emirates has received delivery of its 43rd and 44th A380 aircraft with a double delivery from Airbus' Finkenwerder facility in Hamburg, Germany," the company said in a statement.

"From an operator standpoint, the A380 is still one of the most fuel-efficient aircraft per seat," said the airline's president, Tim Clark.

A flight attendant poses behind the bar in the rear of the business class section of Emirates' Airbus A380. Click for more photos

Inside Emirates' A380

A flight attendant poses behind the bar in the rear of the business class section of Emirates' Airbus A380. Photo: Reuters

The fast-growing airline announced during the Dubai Air Show last month that it has ordered 50 Airbus A380s for $US23 billion ($A26 billion).

The order cemented its status as the single largest operator of the double-deckers. One third of all superjumbos current flying belong to the airline.

Meanwhile, Boeing has won an order from Cathay Pacific for 21 Boeing 777X jets, valued at more than $US7 billion at current list prices, the US company said on Friday.

The deal provides Boeing with a coveted Asian customer for the latest version of its most profitable long-distance passenger jet.

The 777X, due for launch in 2020, will be a derivative of Boeing's top-selling wide-body plane with new wings and engines.

Cathay Pacific expects to take delivery between 2021 and 2024, the airline said.

Industry sources said Cathay Pacific would also increase its fleet of Boeing's existing model, the 777-300ER, by three or four aircraft to meet its medium-term needs. Boeing declined to comment and Cathay Pacific was not available to comment.

Boeing launched the 777X at the Dubai Airshow last month, where it garnered a record 259 orders and commitments worth $US95 billion at list prices from five Gulf and European airlines.

The company is yet to decide where to build the 777X, which is expected to be its only new jetliner programme for the next 15 years along with the narrow-body 737 MAX jet due in 2017.

Union workers in Washington, where Boeing currently builds 777 planes, rejected a contract offer last month, leading the company to consider other places.

The deal is worth $US7.9 billion based on Boeing's published list price for the 406-seat passenger jet but Cathay Pacific said in a filing that the basic price was $US7.464 billion.

Airlines however typically pay much less for aircraft after discounts which are particularly attractive for early customers.

Boeing and Airbus are competing for potential orders of large twin-engined passenger jets designed to seat 350-400 people, which have put pressure on larger four-engined planes.

Emirates has so far dominated the launch with 150 provisional orders which Boeing is trying hard to finalise before the end of the year, according to industry sources.

Qatar also tentatively agreed to buy 50 of the aircraft. Abu Dhabi's Etihad Airways has placed a firm order for 25.

There were conflicting indications over the size of the first European order for the new aircraft.

Lufthansa has said it ordered 34 of the 777X family of aircraft but Boeing's latest order tally shows only 20 of these as firm orders on its backlog.

AFP/Reuters