While American, Delta, and United have many types and variants, it's not always clear which is the most used. We reveal the top-10 aircraft for each operator this winter and where's best to see and fly them. The see the B737-800 is American's most-used aircraft, while it's the A321ceo for Delta and B737-900 for United.

The B737-800 remains king for American

The B737-800 is the most-used aircraft for American this winter, based on analyzing schedules information available via Cirium. One in four flights (25%) are by this aircraft, showing how dominant it is. Notice the MAX 8 in ninth position. Having resumed service 11 months ago, it enters the top-10 table for the first winter.

1. B737-800: 25.6 million round-trip seats in winter 2021
2. A321ceo: 19.6 million
3. A319: 10.7 million
4. Embraer 175: 10.2 million
5. CRJ-700: 7.0 million
6. CRJ-900: 6.8 million
7. Embraer 145: 4.5 million
8. A320: 4.3 million
9. B737 MAX 8: 3.3 million
10. B777-200ER: 3.0 million

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The rise of the Embraer 175

The 76-seat Embraer 175 ranks fourth, close behind the A319. Introduced to American Eagle in 2013, use of the larger regional jet (RJ) has grown significantly in recent years. Why? To benefit from lower seat-mile costs, higher revenue opportunities, and stronger route performance. The E175 has been keenly used to start new routes from Austin.

Summary: American's use of its top-10 aircraft

The table below shows American's most-used aircraft, the airports that see them the most, the number of airports and routes served, and the top route per type. As you'll appreciate, it may change. Notice the A319's top route:  Boston to LaGuardia. While some routes within the Northwest corridor will be withdrawn, in favor of JetBlue, it seems that this won't be.

The carrier's two largest hubs, Dallas and Charlotte, naturally feature heavily. American's North Carolina hub is vital for the A320 and CRJ-900, with the smaller CRJ-700 coming close. The A320, like the A330, was inherited from US Airways, so it is key at two ex-US hubs, Charlotte and Phoenix. In contrast, the B737-800, Embraer 175, and MAX 8 are far less used at Charlotte.

The A220-100 joins Delta's core list this winter

The 191-seat A321ceo is Delta's most-used equipment this year. Introduced in April 2016, available capacity has grown very strongly versus winter 2019, up by 30%. Interestingly, the number-two aircraft, the 180-seat B737-900ER, has reduced in use, with almost one in ten fewer seats this winter. Delta has more B737-900ERs than A321s, although far more of the Airbus type is active.

A notable addition to the table is the A220-100. The carrier has 41 of the 109-seat aircraft, which joined its fleet in October 2018. They have a three-class layout: 12 in first (37" pitch), 15 in comfort plus (34"), and 82 in economy (up to 32"). Delta is by far the largest user of the variant.

1. A321ceo: 14.6 million round-trip seats in winter 2021
2. B737-900ER: 12.4 million
3. CRJ-900: 7.8 million
4. B757-200: 6.9 million
5. Embraer 175: 6.2 million
6. B737-800: 5.9 million
7. A320: 4.9 million
8. B717: 4.3 million
9. A319: 3.6 million
10. A220-100: 2.5 million

The B717 remains reasonably strong

While Delta's seats by the rear-mounted B717 have fallen by a significant 42% versus winter 2019, the aircraft nevertheless ranks eighth and remains reasonably important. Following the withdrawal of Volotea's 717s, Delta is one of only three remaining users of the aircraft worldwide.

Delta opportunistically acquired the B717 from Southwest following its acquisition of AirTran. The type was superfluous to Southwest's one fleet approach, but they were important to Delta partly because they contributed to the big reduction in less economically strong 50-seaters.

Where are Delta's top-10 aircraft most used?

While Atlanta obviously features highly, it does so especially for larger-capacity aircraft. Indeed, earlier this year, we examined seats per flight at Delta, American, and United's hubs. We found that Delta had 149 seats per flight at Atlanta, only one seat below JFK. That JFK was higher was because of a larger share of widebodies and long-haul service at the New York airport.

Not only is Atlanta the best place to see the A321, B737-900ER, and B757-200, but the airport is also very much dominant for them. For example, six in ten of A321 seats are from the Georgia hub, four times more than from second-ranked Minneapolis. It's even starker for the B757, with almost eight in ten seats (77%) to/from Atlanta.

The B737-900 is number-one for United

By glancing at the table below, it's immediately apparent just how much United's fleet revolves around Boeing equipment. Indeed, if United's entire fleet is examined, almost six in ten seats (58%) are by the manufacturer, against 42% for Delta and 35% for American.

Heavy use of the 50-seat CRJ-200 stands out in the top-10 table. In the latest round of cuts, United will remove nine smaller cities from its route map in the early new year. One reason seems to be that the cities, which mainly see 50-seaters, may not sustain the higher capacity, three-class offering of larger RJs to which the carrier is progressively moving.

1. B737-900/900ER: 12.0 million round-trip seats this winter
2. B737-800: 11.1 million
3. Embraer 175: 8.4 million
4. A319: 5.4 million
5. CRJ-200: 5.3 million
6. A320: 5.1 million
7. B737-700: 2.6 million
8. B737 MAX 9: 2.3 million
9. B787-9: 1.9 million
10. B757-300: 1.8 million

Summary: United's use of its top-10 aircraft

The B757-300 makes it into the table for the first time this winter – but the B757-200 doesn't. United has 21 of the large, 234-seat narrowbody -300 variant. They are used on a concentrated basis, with just 15 airports down to see it this winter.

Of these 15 airports, a handful will see it only once or twice, including Fort Lauderdale (from Chicago on December 11th, available for just $48), Tampa (from Chicago on December 25th and January 2nd), and San Jose (from Denver on January 4th and Las Vegas on January 9th).

Of all the aircraft mentioned in this article, what's the most surprising thing for you? Let us know in the comments.