The average age of United’s fleet is estimated to be more than 15 years: a number dragged down by some of the older aircraft the airline currently operates, such as the Boeing 757s and 767s, with certain models of these jetliners having crossed the average age of 20 years.

Aside of the three Dreamliner family members, United also operates another Boeing trio, the 737. Out of a total of 325 Boeing 737 NG (Next Generation) aircraft, the carrier flies 36 of the -700 variant, 141 of the -800 and 148 of the -900. The youngest of the three models is United’s 737-900 fleet with the average age of seven years. The airline has also taken delivery of 10 new 737 MAX 9s with another 126 orders for these jets unfilled.

And then there is the Boeing 777 duo: United operates 98 of these planes. According to the manufacturer, the carrier has 80 aircraft of the -200 variant and another 18 of the -300, the latter aircraft being the youngest in the mix, having taken delivery of the first 777-300 in December 2016.

United does not shy from flying Airbus jets as well. According to the manufacturer’s orders and deliveries book, as of November 2018, the carrier had 167 Airbus jets in its fleet, out of which 68 were A319s and 99 were A320s. United also had placed an order of 45 A350-900 aircraft from Airbus.

United Airlines updated and expanded its previously existing order for 35 Airbus A350-1000 to 45 A350-900 widebody aircraft.

Why the Dreamliner trio?

United has big plans for its newest Dreamliner, expecting to begin international service with the 787-10 in March 2019. The jetliner will serve six trans-Atlantic routes from United’s New York/Newark hub, mainly flying to European destinations, including Frankfurt (Germany), Paris (France), Barcelona (Spain), Brussels (Belgium), and Dublin (Ireland), but also to Tel Aviv (Israel).

Given the emphasis that United puts on passenger comfort, the Boeing 787-10 seems to be a reasonable addition to be deployed on trans-Atlantic routes: it is 18 feet (5.5 meters) longer than the 787-9 model and can carry more passengers and more cargo.

"United is proud to offer more seats between New York and Europe than any other carrier and our Boeing 787-10 aircraft based in New York/Newark will enable us to connect even more New York City customers to Europe and beyond," said Patrick Quayle, United's VP of International Network in an official press release.

In a two-class configuration, the -10 can seat 330, which is 40 more the -9 variant. The -10 has a maximum range of 6,430 nautical miles (11,910 kilometers) and can fly using 20% less fuel than older generation airplanes. However, both smaller Dreamliner family members can fly farther: the -8 has a maximum range of 7,355 nmi (13,620 km), while the -9 can cover 7,635 nmi (14,140 km).

"The 787-10 is an excellent addition to United's fleet. It offers superior fuel efficiency while providing a more comfortable customer experience onboard that allows passengers to arrive at their destinations feeling more refreshed," said Gerry Laderman, chief financial officer at United, in an official press release announcing the welcoming of the airline’s first 787-10.