United Airlines (UA, Chicago O'Hare) has placed its largest-ever single order for narrowbody aircraft, signing up for a total of 200 B737 MAX from Boeing and seventy A321-200neo from Airbus.

The carrier said this B737 MAX order would comprise 150 B737-10s and fifty B737-8s and comes on top of a previously ordered forty B737-8s and ninety-two -10s. The airline also has seventy-nine B737-9s on firm order from the manufacturer, including 30 that have already been delivered.

Concerning Airbus, United Airlines has ordered fifty A321-200NX(XLR)s despite not having had any standard variant A321-200Ns on order thus far.

The airline said the newly ordered aircraft should start delivering in 2023 with the MAX 10s and A321neo to enter service in early 2023. United Airlines plans to take 138 new aircraft in that year alone, including 68 from the newly ordered B737 MAX and sixteen A321neo (the remaining 54 deliveries will be from earlier orders).

United Airlines said it would use the newly ordered aircraft to upgrade its existing narrowbody fleet and replace some 200 regional jets. Although it did not outline the planned rollover's details, Chief Commercial Officer Andrew Nocella confirmed that as a part of the replacement, United would retire all of its fifty-one B757-200s.

The carrier's earlier-generation narrowbody fleet currently comprises eighty-eight A319-100s, ninety-six A320-200s, fifty-three B737-700s, 141 B737-800s, twelve B737-900s, and 136 B737-900(ER)s. It also operates twenty-one B757-300s, the ch-aviation fleets advanced module shows. Its large regional jet fleet comprises twenty CRJ700s operated by SkyWest Airlines (excluding units of the type due for conversion into CRJ550s), and thirty-eight E170s and 196 E175s operated by SkyWest, Republic Airways, and Mesa Airlines.

In an investor presentation, United stressed that it currently lags behind its mainline rivals American Airlines and Delta Air Lines in terms of the average aircraft size operated out of its hubs. This has led to lower yields and suboptimal capacity allocation. However, the planned upgauge to new-generation narrowbodies will reduce the share of single-class regional jet departures at United's hubs from the current 33% to around 10%. The share of large narrowbodies (i.e. A321neo and B737-10) in the carrier's narrowbody fleet will rise from around 4% in 2019 to around 33% once deliveries are completed.

United's average seat count on its North American network is set to grow from 104 seats per departure in 2019 to around 134 in 2026. Most of the growth will be through the expansion of premium cabins. The increase in gauge will cover around a half of United's planned 4-6% annual growth in capacity through 2026, with the remainder contributed through more frequencies and new routes.