United Airlines has emerged as the airline with the largest mainline fleet in the world for 2025, boasting a total of 1,056 aircraft. According to data from ch-aviation, “mainline” refers to aircraft that the carrier operates directly, excluding those contracted to alliance partners or regional subsidiaries. This extensive fleet provides nearly 250,000 seats for passengers, solidifying United’s position at the forefront of the global aviation industry.
United Airlines Fleet Overview
United Airlines primarily relies on a mix of widebody and narrowbody jets to serve its vast network. The most prevalent widebody aircraft in its fleet is the Boeing 777-200ER, of which the airline operates 55 units. In contrast, United has a significant presence of narrowbody jets, particularly the Boeing 737 series, which includes over 100 examples across four variants, such as the 737-800 and 737-900ER.
The following table illustrates the top five widebody and narrowbody aircraft in United’s fleet:
| Variant | In Fleet | Average Age (Years) | Total Capacity |
|---|---|---|---|
| Boeing 777-200ER | 55 | 25.7 | 15,524 |
| Boeing 787-9 | 47 | 6.6 | 11,822 |
| Boeing 767-300ER | 37 | 29.7 | 6,680 |
| Boeing 787-10 | 21 | 5.4 | 6,678 |
| Boeing 777-300ER | 22 | 7.9 | 7,700 |
| Boeing 737-800 | 141 | 21.7 | 23,406 |
| Boeing 737-900ER | 136 | 12.9 | 24,344 |
| Boeing 737 MAX 8 | 123 | 2.8 | 20,418 |
| Boeing 737 MAX 9 | 113 | 3.1 | 20,277 |
| Airbus A319-100 | 81 | 24 | 10,206 |
The total capacity across the entire fleet reaches 238,225 seats. Simultaneously, United has phased out several older aircraft, including the 737-300 and 737-500, to make way for newer models such as the 737 MAX series. The airline has a notable order of 167 MAX 10s that are expected to enhance its fleet further.
Competitors: American and Delta Air Lines
Following closely behind United Airlines are American Airlines and Delta Air Lines, ranked second and third in fleet size. American Airlines operates 1,001 aircraft, with a significant portion being widebody jets from Boeing, including numerous 777 and 787 models. Its narrowbody fleet is robust, comprising 303 Boeing 737-800s and 218 Airbus A321-200s.
Delta Air Lines ranks second with a mainline fleet of 1,010 aircraft. Similar to United, Delta’s fleet is heavily weighted towards narrowbody jets, including 163 Boeing 737-900ERs and 127 Airbus A321-200s. Its widebody aircraft include 39 Airbus A330-900s and 39 Boeing 767-300ERs.
Both airlines have also been proactive in managing their fleets, with American Airlines planning to add 300 new aircraft in the coming years, while Delta has committed to a future investment with 267 firm orders.
United Airlines’ extensive order sheet, featuring 666 jets awaiting delivery, underscores its strategy to maintain and expand its leading position. With an average fleet age of 16.9 years, this order is essential for replacing older aircraft that are nearing the end of their operational lifecycle.
The order sheet includes substantial commitments to the Boeing 737 MAX 10, which United estimates will begin arriving between 2027 and 2028. The airline has strategically opted for the MAX 9 as a temporary solution to address potential capacity constraints during this transition.
United Airlines has also opted not to include the new Boeing 777X in its future fleet plans. The decision reflects a strategic pivot away from high-capacity jets, focusing instead on a multi-hub operational model that allows for efficient long-haul service without heavy reliance on larger aircraft.
United Airlines’ Global Reach
In 2024, United Airlines had approximately 1.6 million scheduled flights, serving a total of 944 routes throughout the year. The busiest domestic route was from Chicago to LaGuardia, averaging 14 flights per day with a total of 435 monthly flights.
Internationally, the airline serves 122 destinations outside the United States, with Toronto Pearson International Airport being the most frequented international destination in May 2024, featuring 697 flights from various U.S. airports. Additionally, United’s operations to London Heathrow Airport included 620 flights in May 2024, underscoring its strong presence in both domestic and international markets.
This comprehensive fleet and strategic planning position United Airlines not only as the largest mainline carrier but also as a critical player in the global aviation landscape.
