Within the US, Airbus has made significant inroads with airlines of all sizes. It has sold hundreds of Airbus A321s to Delta Air Lines, while American Airlines is the world’s largest operator of the A320 family. In the process, however, United Airlines got left behind, and its 2010 merger with Continental Airlines gave it a massive Boeing 737 fleet, a type that it’s continued to order in large quantities over the past 16 years.

It ordered the 737 MAX 8 and 737 MAX 9, while also being one of the launch customers for the 737 MAX 10, initially agreeing to buy 100 in 2017. Nine years later, however, United still doesn’t have a single 737 MAX 10 in its fleet. No airline does, as the type has been delayed by several years and remains uncertified.

Because of these circumstances, United turned away from Boeing and has begun ordering the Airbus A321neo instead. At first, these orders came gradually while United remained firmly committed to the 737 MAX 10, but as time went on, orders for the 737 MAX 10 were converted to the MAX 9, while its orders for the A321neo have increased.

The Dynamics Of The Narrowbody Market

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Airbus and Boeing are known for designing their widebody airliners to be extremely different from one another. In part, this is necessary because the widebody market is relatively small, leading the manufacturers to create planes that fill their own niche rather than compete directly against one another.

The Airbus A330neo is quite similar in size to the Boeing 787, but is optimized for short routes, while the Airbus A350 slots between the 787 and 777X and has more range in all variants. By comparison, the narrowbody space is largely a commodity market. An Airbus A320neo is basically the same plane as the Boeing 737 MAX 8 in terms of how it operates and how much money it makes.

However, Boeing hasn’t made an equivalent aircraft to the A321 ever since the 757 went out of production in 2004. The 737-900 and 737 MAX 9 are much smaller than the A321, resulting in significantly worse per-seat economics, but the 737 MAX 10 is meant to solve this issue. The Boeing 737 MAX 10 is longer and can seat almost as many passengers as the A321neo.

It doesn’t have as much range as a fully-optioned-out A321neo, but it’s still sufficient for almost every airline’s needs, while its economics appear promising. With this, neither aircraft will possess a true advantage over the other in most contests, which means that orders then have to be won mainly on price, terms, and delivery timeline. From an airline’s perspective, there isn’t much difference in operating one versus the other.

United Airlines’ A321neo Orders

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United’s first order for the A321neo had nothing to do with the 737 MAX. In December 2019, United placed an order for 50 examples of the newly launched Airbus A321XLR, the long-range subvariant of the A321neo. United was specifically seeking a new aircraft for thin transatlantic routes, and in the absence of Boeing’s then-expected NMA aircraft (which ultimately never launched), the airline went with the A321XLR to replace its 757-200 fleet.

Notably, this order did not include the standard A321neo. United wouldn’t order that aircraft until 2021, when it ordered 70 A321neos. This came as part of a larger order for 270 narrowbodies, including 50 737 MAX 8s and 150 737 MAX 10s. The carrier would later order another 60 A321neos in 2023, bringing its A321neo order count to 130 examples (180 if counting the A321XLR).

By then, the carrier had accumulated 277 orders for the 737 MAX 10 (although it has since converted some of these to the smaller MAX 9). The 737 MAX 10 was always intended to be the primary domestic workhorse, with the A321neo being more specialized. United installs 200 seats on its A321neos, whereas the 737 MAX 10s will feature 189 seats.

Considering that some of the carrier’s hubs are capacity-constrained and that the airline has generally been increasing capacity, the A321neo’s higher capacity is extremely important. In United’s specifications, these planes are not equipped with any auxiliary fuel tanks, meaning that they actually have less range than the 737 MAX 10. In essence, it serves as a super-efficient, high-capacity shuttle aircraft for United.

Delays With The 737 MAX 10

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When launched, the 737 MAX 10 was meant to enter service in 2020. But with the 737 MAX grounding, subsequent production disruptions from the pandemic, and increased FAA scrutiny, the 737 MAX 10 still has not entered service. It’s now expected that the 737 MAX 10 won’t be certified until late 2026, with initial deliveries delayed until 2027. This represents a major problem for United, a carrier that has been rapidly growing the size of its narrowbody fleet and upgauging flights.

In January 2024, a door plug blew out of an Alaska Airlines 737 MAX 9, resulting in the MAX 9 being temporarily grounded. This was a severe blow to United Airlines, the world’s largest MAX 9 operator, and CEO Scott Kirby called the accident ‘the straw that broke the camel’s back’. Combined with the MAX 10 delays, it became clear to United that relying only on Boeing was risky. Shortly afterward, Kirby personally flew to Toulouse to discuss options with Airbus on more A321neos.

Since the meeting, United has removed the 737 MAX 10 from its internal planning. This doesn’t mean that the orders were canceled, but rather that the airline would plan its fleet and network without the MAX 10 in mind. On the Airbus side, this has resulted in more orders for the A321neo to increasingly take the 737 MAX 10’s role. Meanwhile, United has also converted 110 orders for the MAX 10 to the MAX 9 variant, since these planes can be delivered now.

The New Role Of The A321neo

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Previously, the A321XLR was purchased to replace the 757, and then a small order of A321neos was placed later to essentially serve the same role as the 737 MAX 10, but with slightly more seats and less range. Before 2024, United ordered 180 A321neos (including the XLR), making it a small fleet in comparison to the nearly 300 MAX 10s ordered and the 514 737 MAXs ordered in total.

However, since United’s shift away from the MAX 10, the carrier has been increasing its orders for the A321neo. It signed a lease agreement with multiple lessors for a total of 40 A321neos in 2024, to be delivered starting in 2026. Powered by the CFM LEAP (United’s own A321neos have Pratt & Whitney engines), these aircraft are confirmed to be coming with a new three-class layout for transcontinental routes, and have been dubbed the ‘Coastliner’.

United plans to operate 50 Coastliners in total (likely meaning that there will be ten PW-powered A321neos in this layout), and this notably replaces United’s previous plan to operate 50 737 MAX 10s with lie-flat seats. In 2025, United was revealed to have placed a previously undisclosed order for 40 A321neos, to be delivered after 2030.

In total, the carrier has now ordered 260 A321neos (including 40 leased A321neos and 50 A321XLRs), creating a larger fleet than the 737 MAX 10. The latter was originally meant to be the future of United’s narrowbody fleet, but the A321neo is available and compelling in its own right. Meanwhile, United has also been taking 737 MAX 9s rapidly, and it’s these two aircraft that will be the backbone of United’s fleet rather than the 737 MAX 10.

United’s A321neo Subfleets

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As previously mentioned, United will be operating 260 A321neos as per its current orderbook. 160 of these will be in a standard domestic configuration with 200 seats (split between 20 United First seats and 180 economy seats), and essentially equivalent to how United will use its 167 737 MAX 10s (which have 11 fewer economy seats).

While United has run ETOPS-proving flights with the A321neo, its lack of auxiliary fuel tanks means that it’s range-limited as is. As such, the A321neo will likely remain confined to the continental US while the MAX 10 will run to Hawaii and the Caribbean. The 40 leased A321neos are equipped with CFM LEAP-1A engines, and they will be configured with 20 Polaris lie-flat seats (based on the Elevate Altitude), as well as 12 Premium Plus seats and 129 economy seats.

Dubbed the ‘Coastliner’, United is planning a total of 50 planes with this configuration, which likely means that ten Pratt & Whitney-powered A321neos will be configured in the Coastliner layout. Meanwhile, United has recently taken delivery of its first of 50 A321XLRs, the variant that it first ordered back in 2019.

These aircraft are slated to replace the 757-200 on transatlantic routes, and will feature the same amount of Polaris/Premium Plus seats as the Coastliner, but with 11 fewer economy seats. Notably, United only flies 40 757-200s, which operate transatlantic and transcontinental routes, but they will be replaced by 100 lie-flat-equipped Coastliners/A321XLRs, representing significant growth in both markets.