In 2024, Delta Air Lines and United Airlines were the leading airlines in the U.S., with a domestic market share of 21 percent. That year, American Airlines had the second-largest market share of 20 percent. U.S. airlines' domestic market share The passenger air transportation market is a thriving industry, taking individuals to locations around the globe. American Airlines was the third largest airline in the North America based on operating revenue, reaching nearly 40.5 billion U.S. dollars in 2023. Passenger airlines can face much scrutiny for their passenger satisfaction and comfort. A 2025 North American Airline Satisfaction Study by J.D. Power & Associates listed Southwest Airlines as the best long-haul, closely followed by low-cost carrier JetBlue Airways. United Airlines, Delta Air Lines, American Airlines and Southwest Airlines are the top-ranked airlines based on 2024 domestic market share. Delta operates out of Atlanta, and Hartsfield-Jackson Atlanta International Airport, Delta’s hub, sees the most passenger traffic in the United States. Chicago-headquartered United Airlines is a subsidiary of United Continental Holdings. United has flights to 210 domestic destinations and 120 destinations internationally.
IndiGo held around **** percent of the international airlines market during financial year 2024, out of the 87 scheduled international operators across India. Emirates held almost *** percent of the international market in the south Asian country, whereas the airline was ranked as the fourth leading airline worldwide based on brand value.
The global airline industry's revenue distribution showcased the dominance of established markets, with the United States and Canada leading at **** percent market share. This North American stronghold was closely followed by Europe at **** percent, while emerging markets in Latin America contributed a modest * percent to the industry's revenue landscape. North American carriers maintain leadership American carriers continued to set the pace in the global airline sector. American Airlines stood out as a front-runner, operating ******* flights in North America in 2024, surpassing Delta Air Lines' ******* flights. This operational prowess was similar in passenger traffic, with American Airlines carrying nearly *** million passengers in 2023, while Delta Air Lines followed with *** million. The financial implications of the company were significant. In the fiscal year 2023, American Airlines Group's operating revenue was **** billion U.S. dollars, representing an eight percent increase from the previous year. Ancillary revenue and Middle Eastern growth While North American carriers led in overall market share, other regions and revenue streams were gaining importance. In 2023, Middle Eastern carriers were making significant strides in passenger traffic. Emirates Airline transported nearly ** million passengers in 2023, with Qatar Airways Group following at ** million, highlighting the growing influence of Middle Eastern airlines in the global aviation landscape.
https://www.cognitivemarketresearch.com/privacy-policyhttps://www.cognitivemarketresearch.com/privacy-policy
According to Cognitive Market Research, the global Airline Industry market size will be USD 548415.2 million in 2024. It will expand at a compound annual growth rate (CAGR) of 4.00% from 2024 to 2031.
North America held the major market share for more than 40% of the global revenue with a market size of USD 219366.08 million in 2024 and will grow at a compound annual growth rate (CAGR) of 2.2% from 2024 to 2031.
Europe accounted for a market share of over 30% of the global revenue with a market size of USD 164524.56 million in 2024 and will grow at a compound annual growth rate (CAGR) of 2.5% from 2024 to 2031.
Asia Pacific held a market share of around 23% of the global revenue with a market size of USD 126135.50 million in 2024 and will grow at a compound annual growth rate (CAGR) of 6.0% from 2024 to 2031.
Latin America had a market share of more than 5% of the global revenue with a market size of USD 27420.76 million in 2024 and will grow at a compound annual growth rate (CAGR) of 3.4% from 2024 to 2031.
Middle East and Africa had a market share of around 2% of the global revenue and was estimated at a market size of USD 10968.30 million in 2024 and will grow at a compound annual growth rate (CAGR) of 3.7% from 2024 to 2031.
The Passenger Aircraft held the highest Airline Industry market revenue share in 2024.
Market Dynamics of Airline Industry Market
Key Drivers for Airline Industry Market
Increased demand for air cargo to propel market growth
Increased demand for air cargo is a key driver of growth in the airline sector market. The advent of e-commerce, combined with global supply chain integration, has increased the demand for rapid and dependable delivery services. Airlines are profiting from this trend by increasing cargo capacity, investing in specialist freighter aircraft, and improving logistics. Furthermore, the increased importance of carrying high-value, time-sensitive items like medications and electronics drives up demand. By focusing on air cargo, airlines may diversify income streams, increase profitability, and reduce the volatility of passenger travel demand, ensuring long-term market growth.
Growing technological advancements to propel market growth
Technological advances are expected to drive significant expansion in the airline sector market. Aircraft design innovations, such as more fuel-efficient engines and lightweight materials, help to minimize operational costs and environmental effects. Advanced avionics and navigation systems increase safety and efficiency, while digital technologies such as artificial intelligence and big data analytics improve route planning, maintenance, and customer service. The use of automation in ticketing, check-in, and baggage processing enhances both the passenger experience and operational efficiency. Furthermore, the use of in-flight connections and individualized entertainment selections improves client happiness. Airlines that embrace these technological innovations can raise competitiveness, save costs, and satisfy changing consumer expectations, resulting in long-term market growth and profitability.
Restraint Factor for the Airline Industry Market
Volatility in Fuel Prices
Jet fuel costs account for a significant portion of an airline's operating expenses. Since global oil prices are highly unpredictable and influenced by geopolitical events, inflation, and supply chain disruptions, even small fluctuations can heavily impact profitability. Airlines operating on thin margins often struggle to absorb sudden price increases, especially low-cost carriers.
Regulatory and Environmental Compliance Pressure
Airlines face increasingly stringent regulations related to emissions, noise pollution, and operational safety—especially in regions like the EU and North America. Compliance with these regulations often requires substantial investment in new technology, fleet upgrades, and reporting infrastructure, which increases operational costs and delays profitability.
Key Trends of the Airline Industry Market
Focus on Sustainable Aviation and Green Technologies
Sustainability is becoming a critical priority for both airlines and consumers. Airlines are increasingly investing in sustainable aviation fuels (SAFs), carbon offset programs, and next-generation aircraft with improved fuel efficiency. This trend is driven by consumer demand, investor pre...
https://www.polarismarketresearch.com/privacy-policyhttps://www.polarismarketresearch.com/privacy-policy
Global airlines market size and share are estimated to attain USD 473.91 billion by 2032, with a forecasted CAGR of 3.53% during the period. The domestic segment accounted for the largest market share in 2022, which is mainly driven by its low air fares and increasing standard of living.
India’s aviation sector has increasingly emerged as a fast-growing industry. The sector had established itself as an affordable and credible alternative to the tedious and long journeys via road or rail. With a visible growth trend, it was estimated that by 2034, India would become one of the largest aviation markets in the world. As of financial year 2024, the passenger carrier IndiGo was the leader in the segment with around 62 percent of the market. IndiGo - the market leader The Indian aviation sector handled over 376 million passengers at Indian airports the same year. Jet Airways held the largest market share after IndiGo as of 2018. But the former passenger carrier had suspended operations in April 2019 following financial difficulties, leaving the field open for the latter, with little competition from other players in the market. A flight for the budget airline market Indigo airline’s low-cost and no-frills approach to domestic flying has been cited as one of the factors leading to its relative success in India. According to the Directorate-General of Civil Aviation, IndiGo airline carried over 106 million passengers during the fiscal year 2024. It ranked the first among the country’s most punctual airlines with above 88 percent on-time arrivals. As a carrier that also had the least complaints from the customers, IndiGo’s popularity with the domestic base was high, soaring towards growth in the years to come.
https://www.ibisworld.com/about/termsofuse/https://www.ibisworld.com/about/termsofuse/
Market Size statistics on the Global Airlines industry in Global
https://www.cognitivemarketresearch.com/privacy-policyhttps://www.cognitivemarketresearch.com/privacy-policy
Global AirLine market size 2025 was XX Million. AirLine Industry compound annual growth rate (CAGR) will be XX% from 2025 till 2033.
https://www.thebusinessresearchcompany.com/privacy-policyhttps://www.thebusinessresearchcompany.com/privacy-policy
Global Airlines market size is expected to reach $827.27 billion by 2028.6 at 8.6%, rising air passenger numbers propel airline market growth
https://www.imarcgroup.com/privacy-policyhttps://www.imarcgroup.com/privacy-policy
The global low cost airlines market size reached USD 221.3 Billion in 2024. Looking forward, IMARC Group expects the market to reach USD 430.5 Billion by 2033, exhibiting growth rate (CAGR) of 7.29% during 2025-2033. The rising domestic travel and tourism, widespread adoption of ticketless travel, the growing internet penetration, and inflating consumer disposable income in developing nations are some of the major factors propelling the market.
https://www.datainsightsmarket.com/privacy-policyhttps://www.datainsightsmarket.com/privacy-policy
The global domestic aviation market is experiencing robust growth, driven by increasing disposable incomes, expanding middle classes in developing economies, and a surge in demand for convenient and efficient travel. The market, estimated at $500 billion in 2025, is projected to witness a Compound Annual Growth Rate (CAGR) of 6% from 2025 to 2033, reaching approximately $800 billion by 2033. This growth is fueled by several key factors including the continuous expansion of low-cost carriers offering affordable fares, advancements in aircraft technology leading to improved fuel efficiency and passenger comfort, and the development of sophisticated airport infrastructure. Government initiatives aimed at boosting tourism and improving air connectivity in various regions also contribute significantly. While fuel price volatility and economic downturns pose challenges, the market's inherent resilience and the long-term growth prospects of air travel are expected to outweigh these short-term restraints. The market is segmented by aircraft type (fixed-wing and spiral wing—with fixed-wing dominating) and application (government, commercial, and private—with commercial commanding the largest share). Key players like Singapore Airlines, Air New Zealand, Qantas, and others are strategically investing in fleet modernization and expanding their route networks to capitalize on this growth. Regional variations exist, with North America and Asia Pacific expected to retain strong market leadership due to robust economies and high travel demand, though growth in emerging markets in South America and Africa is gaining momentum. The Asia-Pacific region, particularly China and India, is anticipated to display the most significant growth due to rapid economic expansion and increasing urbanization. North America also holds a substantial market share owing to the established aviation industry and high consumer spending on travel. Europe, while mature, continues to experience steady growth spurred by increased tourism and intra-regional travel. The Middle East and Africa are projected to see moderate growth, driven by infrastructure development and increased investment in the airline sector. However, the success of these regions will be contingent on addressing infrastructural limitations and the adoption of sustainable aviation practices. Overall, the domestic aviation market presents significant investment opportunities, particularly in emerging markets and sectors focusing on sustainable technologies.
https://www.ibisworld.com/about/termsofuse/https://www.ibisworld.com/about/termsofuse/
Demand for international airlines has been very volatile over the past five years. Much of the industry benefited from a constant need for travel, both for seasonal vacations and business trips. The ongoing economic recovery from the pandemic and pent-up consumer demand led to revenue spikes. But lately, much of the industry has been dealing with high costs and debt, lowering profit levels. Overall, revenue has expanded at a CAGR of 15.8% to $96.8 billion over the past five years, including a gain of 1.2% in 2025 alone. Industry profit has climbed to 3.0% of revenue in 2025, up from -21.3% in 2020. International tourism from US and non-US residents has rebounded lately, boosting this industry. Charging ancillary fees such as checked baggage fees and seat selection fees have helped airlines generate more revenue in the period, even though the government views these practices with concern. A potential shortage of pilots is a cause for concern for this industry as more pilots are about to reach retirement age. Airlines are countering this problem by hiring more new pilots. Revenue is expected to stagnate in the coming years as geopolitical conflicts restrict where airlines can operate, harming revenue streams. At the same time, regulations regarding charging junk fees are anticipated to continue being scrutinized by the government, which will keep their operations in check. However, climbing international travel activity will help airlines limit revenue declines during the outlook period. A need for labor will maintain high wage costs, and the reality of labor unions representing pilots and mechanics also poses an issue to airlines due to higher wage expenses. Overall, industry revenue is expected to decline at a CAGR of 0.1% to $96.5 billion over the five years to 2030.
https://www.mordorintelligence.com/privacy-policyhttps://www.mordorintelligence.com/privacy-policy
The Europe Aviation Market Report is Segmented by Type (Commercial Aviation, Military Aviation, and General Aviation) and Geography (United Kingdom, Germany, France, Italy, Spain, Russia, and the Rest of Europe). The Report Offers Market Size and Forecast for all the Above Segments in Value (USD).
https://www.polarismarketresearch.com/privacy-policyhttps://www.polarismarketresearch.com/privacy-policy
Worldwide airlines market szie and share is expected to generate revenue of USD 473.91 billion, with an impressive CAGR of 3.53% anticipated between 2023 to 2032.
https://www.ibisworld.com/about/termsofuse/https://www.ibisworld.com/about/termsofuse/
The industry has navigated a significant recovery, driven by strong rebounds in passenger demand as travel habits returned to pre-pandemic norms. These surges in travel increased operational pressure, mainly because of persistent delays in aircraft deliveries. As a result, airlines extended aircraft leases to maintain sufficient fleet capacity. This approach offered stable cost management and enabled continued operations, yet it also slowed the growth of airfares as access to additional aircraft softened pricing power across the sector. Balancing regulated airfare growth, airlines shifted their focus toward ancillary revenue streams. Embracing an unbundled pricing model, mirroring the strategy of low-cost carriers (LCCs), allowed traditional airlines to generate extra revenue by charging separately for services like checked baggage and seat selection, in response to intense competition luring travelers toward more affordable LCC options. The industry also grappled with a persistent pilot shortage, affecting the speed of recovery and challenging workforce stability. Training gaps and constraints in bringing new pilots onboard prompted airlines to invest in enhanced in-house training facilities to expedite recruitment and keep up with demand. Technological changes shifted the focus from traditional Global Distribution Systems (GDS) to New Distribution Capabilities (NDC), enabling carriers to offer real-time, dynamically priced fares through more adaptable sales channels. This transition prompted updated fee structures and facilitated commission-based incentives for partners using the NDC platform, providing new profitability streams even as challenges continued. Overall, the industry’s total revenue grew at a CAGR of 23.0% from 2020 to 2025, reaching an estimated $837.0 billion. However, recent yearly growth slowed significantly to just 0.1% forecasted in 2025. The industry will need to adapt to emerging travel trends. There’s expected growth in leisure and business travel to historically less-popular destinations, which could add new market opportunities. Yet passengers from these regions exhibit more conservative spending habits, tempering the expected revenue impact. Fulfilling overdue aircraft orders should strengthen operational capacity, allowing airlines to better meet demand on profitable routes and lift premiums when justified by high demand. The ongoing roll-out of NDC systems will help streamline booking, although rising IT costs, driven by system upgrades and integration, will likely impact the industry’s expense structure soon. Combined with efforts to bring back corporate travel, new revenue channels and tighter cost controls are expected to sustain moderate performance. Projections estimate industry revenue will rise at a CAGR of 1.6% to $906.7 billion by 2030, indicating a slower but steady expansion as operational efficiency and diversification shape future growth.
Commercial Airlines Market Size 2025-2029
The commercial airlines market size is forecast to increase by USD 430.2 billion, at a CAGR of 8.7% between 2024 and 2029.
The market is experiencing significant growth, driven primarily by the increasing air passenger traffic. This trend is expected to continue as the global population grows and disposable income increases, leading to an expansion in the number of people traveling for business and leisure purposes. Another key driver is the rising preference for smart airports, which offer enhanced passenger experiences through advanced technology and improved infrastructure. However, this market is not without challenges. Operating expenses are on the rise due to factors such as fuel costs, labor expenses, and maintenance fees. These costs can put pressure on airlines' profitability and require strategic planning to mitigate their impact.
Additionally, the industry faces regulatory challenges, including safety regulations and environmental concerns, which can impact operational efficiency and require significant investments in compliance. To capitalize on market opportunities and navigate challenges effectively, airlines must focus on optimizing their operations, investing in technology, and building strong partnerships with industry stakeholders.
What will be the Size of the Commercial Airlines Market during the forecast period?
Explore in-depth regional segment analysis with market size data - historical 2019-2023 and forecasts 2025-2029 - in the full report.
Request Free Sample
The commercial aviation market continues to evolve, with dynamic market activities shaping various sectors. Aviation security remains a top priority, with continuous advancements in technology and regulations. Freight forwarding is experiencing growth, driven by the increasing demand for efficient supply chain management. Customer service is a key differentiator, with full-service carriers investing in personalized travel experiences and loyalty programs. Fuel efficiency is a major focus, with the adoption of smart airports, cloud computing, and in-flight entertainment systems. Hybrid aircraft and electric aircraft are emerging technologies, offering potential for reduced carbon emissions and cost savings. Route planning and hub airports are essential components of fleet management, with real-time data analysis and optimization techniques improving operational efficiency.
Autonomous aircraft and artificial intelligence are transforming aircraft leasing and maintenance, enabling predictive maintenance and fleet optimization. Cargo flights and air cargo are integral to business travel and e-commerce, with the integration of biometric authentication streamlining the passenger experience. Flight cancellations and delays are ongoing challenges, with digital transformation and real-time communication tools improving response times and reducing disruptions. Safety regulations and air traffic control remain critical, with ongoing collaboration between stakeholders ensuring a safe and efficient aviation industry. Airline alliances and low-cost carriers are shaping the competitive landscape, with online ticketing and baggage handling services enhancing the passenger experience.
The aviation industry is a complex and ever-changing ecosystem, with ongoing innovation and adaptation essential for success.
How is this Commercial Airlines Industry segmented?
The commercial airlines industry research report provides comprehensive data (region-wise segment analysis), with forecasts and estimates in 'USD billion' for the period 2025-2029, as well as historical data from 2019-2023 for the following segments.
Revenue Stream
Passenger
Cargo
Type
International
Domestic
Range Outlook
Short-haul
Medium-haul
Long-haul
Ultra-long haul
Fuel Efficiency
Conventional Jet Fuel
Biofuels
Electric Propulsion
Hydrogen-powered
Operation Model
Scheduled Flights
Charter Flights
Wet Leasing
Business Model
Network Carriers
Point-to-Point Carriers
Ultra-Low-Cost Carriers (ULCCs)
Geography
North America
US
Canada
Europe
France
Germany
Italy
UK
Middle East and Africa
Egypt
KSA
Oman
UAE
APAC
China
India
Japan
South America
Argentina
Brazil
Rest of World (ROW)
.
By Revenue Stream Insights
The passenger segment is estimated to witness significant growth during the forecast period.
The market experienced significant activity in 2024, with the passenger segment leading the growth. The surge in air travel, particularly in the APAC region, drove this trend, resulting in approximately 4.6 billion passenger footfalls in airports, marking a 28.3% increase. In response, major aircraft Original Equipment Manufacturers (OEMs) are upgrading their production facilities to meet
https://www.mordorintelligence.com/privacy-policyhttps://www.mordorintelligence.com/privacy-policy
The Aviation Market Report is Segmented by Type (Commercial Aviation, Military Aviation, General Aviation, Unmanned Aerial Systems, and Advanced Air Mobility), Propulsion Technology (Turboprop, Turbofan, Piston Engine, and More), Power Source (Conventional Fuel, Fuel Cell, and More), Fit (Line Fit, and Retrofit), and Geography (North America, Europe, and More). The Market Forecasts are Provided in Terms of Value (USD).
https://www.archivemarketresearch.com/privacy-policyhttps://www.archivemarketresearch.com/privacy-policy
The global airline industry, valued at $614.3 billion in 2025, is projected to experience steady growth, with a Compound Annual Growth Rate (CAGR) of 2.8% from 2025 to 2033. This growth is driven by several factors, including the increasing affordability of air travel, particularly on regional routes, a rise in disposable incomes globally fueling leisure travel, and the expansion of low-cost carriers. The industry is segmented by route type (long-range and regional) and travel type (domestic and international). International travel, particularly between major hubs in North America, Europe, and Asia-Pacific, contributes significantly to the market's overall value. Technological advancements, such as improved aircraft efficiency and enhanced booking platforms, also contribute positively to the sector's expansion. However, the industry faces challenges including fluctuating fuel prices, geopolitical instability impacting travel demand, and increased competition amongst established and emerging players. While North America and Europe currently hold the largest market shares, the Asia-Pacific region is expected to experience significant growth driven by rapid economic development and rising middle classes in countries like China and India. This growth will likely lead to increased competition for market share among major airlines globally. Continued focus on sustainability initiatives, enhancing passenger experience, and adapting to evolving consumer preferences will be crucial for airlines to maintain profitability and market competitiveness in the coming years. The projected market size in 2033 can be estimated based on the provided CAGR of 2.8% and 2025 market size. Applying this growth rate year-over-year, we project substantial growth across all segments. The long-range route segment is anticipated to maintain significant market share due to the increasing demand for international travel, while the regional route segment will likely see substantial growth fueled by the rise of low-cost carriers and increased domestic travel. Similarly, within the application segment, both domestic and international travel sectors are predicted to expand, although the proportion of international travel is expected to be relatively higher considering global travel trends. Key players, including those mentioned, will leverage strategic alliances, fleet modernization, and expansion into new markets to strengthen their competitive positions within this dynamic and growing landscape.
https://www.promarketreports.com/privacy-policyhttps://www.promarketreports.com/privacy-policy
Passenger Aircraft: Passenger aircraft are designed to transport passengers. They range from small turboprops to large wide-body jets.Freighter Aircraft: Freighter aircraft are designed to transport cargo. They are typically converted from passenger aircraft or designed specifically for cargo transportation.Combat Aircraft: Combat aircraft are designed for military operations, including air-to-air combat, ground attack, and reconnaissance.Non-Combat Aircraft: Non-combat aircraft are designed for military support roles, such as aerial refueling, surveillance, and transportation.Helicopters: Helicopters are used for a wide range of applications, including transportation, emergency services, and military operations.Piston Fixed-Wing Aircraft: Piston fixed-wing aircraft are small, single-engine aircraft used for recreational and training purposes.Turboprop Aircraft: Turboprop aircraft are propeller-driven aircraft powered by turbine engines. They offer a combination of speed and efficiency.Business Jets: Business jets are designed for private or corporate transportation. They offer speed, comfort, and privacy. Key drivers for this market are: Increasing Passenger Demand Rising Disposable Income. Potential restraints include: A Competitive Market with Low Margins Fluctuating Fuel Prices. Notable trends are: Artificial Intelligence and Automation Data Analytics and Personalization.
https://www.datainsightsmarket.com/privacy-policyhttps://www.datainsightsmarket.com/privacy-policy
The global airline industry, valued at $633.03 billion in 2025, is projected to experience steady growth, with a compound annual growth rate (CAGR) of 2.9% from 2025 to 2033. This growth is driven by several factors, including the increasing affordability of air travel, particularly in emerging economies with expanding middle classes. Furthermore, advancements in aircraft technology leading to greater fuel efficiency and reduced operating costs contribute to the industry's positive outlook. The rise of low-cost carriers (LCCs) continues to reshape the competitive landscape, offering budget-friendly options and stimulating demand, particularly on regional routes. However, the industry faces challenges such as fluctuating fuel prices, geopolitical instability impacting travel patterns, and the ongoing need to adapt to evolving consumer preferences and sustainable practices. The industry's segmentation reveals a significant reliance on both domestic and international travel, with long-range routes commanding premium pricing and contributing substantially to overall revenue. Regional routes, often served by LCCs, provide higher volume but lower profit margins. The competitive landscape includes major global players like Air France KLM, American Airlines, and Delta, alongside prominent regional carriers catering to specific market needs. Geographical distribution indicates a significant market share for North America and Europe, fueled by established infrastructure and high levels of disposable income. However, the Asia-Pacific region is expected to witness the most significant growth over the forecast period, driven by rapid economic development and increasing air travel demand in countries like China and India. The Middle East and Africa also present notable opportunities, particularly with investment in airport infrastructure and expanding tourism. The industry's future success hinges on effective management of operational costs, strategic route planning, adaptation to evolving technological advancements, and a focus on sustainability to mitigate environmental concerns and meet evolving regulatory demands. Successful players will be those that effectively balance profitability with accessibility, catering to diverse passenger segments and utilizing data analytics to optimize operations and enhance the customer experience.
In 2024, Delta Air Lines and United Airlines were the leading airlines in the U.S., with a domestic market share of 21 percent. That year, American Airlines had the second-largest market share of 20 percent. U.S. airlines' domestic market share The passenger air transportation market is a thriving industry, taking individuals to locations around the globe. American Airlines was the third largest airline in the North America based on operating revenue, reaching nearly 40.5 billion U.S. dollars in 2023. Passenger airlines can face much scrutiny for their passenger satisfaction and comfort. A 2025 North American Airline Satisfaction Study by J.D. Power & Associates listed Southwest Airlines as the best long-haul, closely followed by low-cost carrier JetBlue Airways. United Airlines, Delta Air Lines, American Airlines and Southwest Airlines are the top-ranked airlines based on 2024 domestic market share. Delta operates out of Atlanta, and Hartsfield-Jackson Atlanta International Airport, Delta’s hub, sees the most passenger traffic in the United States. Chicago-headquartered United Airlines is a subsidiary of United Continental Holdings. United has flights to 210 domestic destinations and 120 destinations internationally.