For this ranking, “passenger traffic” refers primarily to the number of passengers, customers, or enplaned passengers carried by an airline group in 2024, using the latest publicly available company disclosures. This is important because airline traffic can be reported in different ways. Some companies use passenger count, while others emphasize revenue passenger kilometers, or RPKs, which measure passengers carried multiplied by distance flown. Air China’s annual report, for example, notes that passenger traffic is measured in RPKs unless otherwise specified, showing why the definition must be made clear.

This article ranks airline groups by passenger volume, not by revenue, market capitalization, fleet size, or distance-weighted traffic. Where airlines report “customers,” “guests,” or “enplaned passengers,” the closest comparable passenger-volume figure is used. In a few cases, figures are rounded or based on different fiscal reporting periods, which is noted where relevant.

The ranking is heavily shaped by the size of domestic air travel markets. In 2024, the United States remained the world’s largest passenger market with 876 million passengers, followed by China with 741 million. The next-largest markets were far smaller: the United Kingdom at 261 million, Spain at 241 million, India at 211 million, and Japan at 205 million.

That explains why seven of the ten largest airline groups by passenger traffic are based in either the United States or China. Large domestic markets allow airlines to operate high-frequency routes, connect smaller cities through major hubs, and fill aircraft even before international demand is included. The result is a powerful scale advantage: airlines in large domestic markets can carry massive passenger volumes without relying entirely on long-haul international traffic.

American Airlines leads the ranking because of its vast U.S. domestic footprint, regional partner network, and major hubs such as Dallas-Fort Worth, Charlotte, Miami, Chicago, Philadelphia, Phoenix, and Los Angeles. The company reported 226.4 million revenue passengers in 2024, its highest figure since the US Airways merger.

The largest airlines do not all operate the same way. Some are full-service network carriers built around hubs, alliances, loyalty programs, and long-haul connectivity. Others are low-cost carriers that generate volume through high aircraft utilization, short-haul frequency, and simplified operations.

American, Delta, United, China Southern, Air China, China Eastern, Lufthansa Group, and IAG are primarily network airline groups. Their scale comes from connecting domestic, regional, and international routes through hub systems. Ryanair and Southwest, by contrast, are high-volume short-haul carriers whose traffic strength comes from frequent point-to-point operations and large domestic or regional networks.

This difference matters because passenger traffic is not the same as revenue quality. A short-haul airline may carry more passengers than a long-haul carrier, while a long-haul carrier may generate more revenue per passenger because each trip covers greater distance and often includes premium cabins.

Network carriers dominate the top tier because they combine domestic passenger flow with connecting traffic. Delta served more than 200 million customers in 2024 while operating up to 5,000 flights per day to more than 290 destinations. United carried nearly 174 million customers and operated more than 4,300 daily flights, supported by a large domestic system and one of the strongest international networks among U.S. carriers.

The Chinese carriers show the same principle at national scale. China Southern carried 164.73 million passengers in 2024, while Air China carried 155.32 million and China Eastern served 141 million. These airlines benefit from China’s enormous domestic travel base, but their international recovery and profitability depend heavily on route reopening, outbound travel demand, and competitive pricing.

European network groups are large, but they operate in a more fragmented market. Lufthansa Group carried 131.3 million passengers in 2024, while IAG carried about 122 million. Both groups operate major brands across multiple countries, but Europe’s market is divided across national carriers, low-cost airlines, rail competition, and slot-constrained airports.

Ryanair’s position near the top of the global ranking shows the power of the low-cost model. The group carried about 197.1 million passengers in calendar 2024 based on its monthly traffic disclosures, and it later reported 200.2 million passengers for its fiscal year ending March 2025.

Ryanair’s scale comes from short-haul European routes, dense scheduling, high aircraft utilization, and a point-to-point network that avoids many of the complexity costs associated with full-service hub operations. It may not match the global network reach of American, Delta, or United, but it competes aggressively on passenger volume.

Southwest is the U.S. version of that volume-driven model. The airline reported 175.5 million enplaned passengers in 2024, making it one of the largest carriers in the world by passenger boardings. Its strength is rooted in domestic U.S. demand, high-frequency routes, and a historically simplified operating model focused on narrowbody aircraft.

Passenger count is only one way to measure airline size. It tells us how many people an airline moves, but it does not fully capture distance, fare levels, premium cabin mix, cargo revenue, loyalty economics, or profitability.

OAG’s 2024 airline analysis shows how different scale metrics can produce different leaders. Among the world’s 20 largest scheduled airlines, American Airlines had the highest scheduled seat capacity at 275.5 million seats and operated 2.2 million flights, while United Airlines led on available seat kilometers, a distance-weighted measure of capacity.

This distinction is critical. A carrier with many short-haul passengers can rank highly by passenger traffic, while a carrier with fewer long-haul passengers may rank higher by available seat kilometers or revenue. That is why airlines such as Emirates or Qatar Airways can be strategically powerful global carriers even if they do not rank among the top passenger-volume airlines.

The ranking reflects a broader recovery and expansion in global aviation. IATA reported that total air passenger demand rose 10.4% in 2024, with industry load factor reaching 83.5%. International traffic also surpassed 2019 levels for the first time, while domestic traffic continued to set new records.

In absolute terms, IATA’s industry data show 4.774 billion segment passengers in 2024, with the figure expected to rise to 4.982 billion in 2025 and 5.202 billion in 2026. Airline passenger revenue reached $687 billion in 2024, out of total industry revenue of $969 billion.

That means the world’s largest airlines are competing in a market that is not only recovering but expanding. Passenger growth is being driven by domestic resilience, international reopening, leisure demand, and the rising importance of fast-growing markets such as India, Southeast Asia, and parts of the Middle East.

Several forces could change the ranking over the next few years.

First, India is becoming a major aviation growth market. IATA ranked India as the fifth-largest passenger market in 2024, with 211 million passengers. As Indian carriers expand fleets and international routes, the country could produce more top-ranking airline groups by passenger traffic.

Second, China’s international travel recovery still has room to influence the ranking. The major Chinese carriers already rank among the world’s largest by passenger volume, but their future position will depend on outbound tourism, international capacity restoration, and domestic pricing strength.

Third, aircraft delivery constraints could limit growth. Ryanair, for example, said Boeing delivery delays affected its growth plans and guided for slower passenger growth to 206 million in fiscal 2026. For high-volume airlines, fleet availability directly affects how many passengers they can carry.

Fourth, mature U.S. airlines may focus less on raw passenger growth and more on revenue quality. American, Delta, United, and Southwest already operate at enormous scale. Their next phase of competition is likely to depend on premium revenue, loyalty programs, international expansion, operational reliability, and cost discipline.

The largest airline groups by passenger traffic are the companies best positioned to combine large home markets, dense route networks, high aircraft utilization, and strong connecting systems. American Airlines leads the ranking, followed by Delta, Ryanair, Southwest, and United, while China’s three major airline groups highlight the scale of Asia’s largest aviation market.

The central lesson is clear: passenger traffic is not simply a measure of airline popularity. It is a measure of network power. The airlines that move the most people are those that sit at the intersection of population scale, airport access, fleet capacity, route density, and operating efficiency. As global passenger demand continues to rise, the next shift in the ranking will likely come from fast-growing aviation markets, especially India and China, as well as from low-cost carriers that can turn frequency and affordability into massive passenger volume.