US aviation market briefing
Latest flight data insights and analysis from America
September 2026
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US seat capacity, 2025 and 2026
US domestic & international capacity: 2025 vs 2026
Top 10 US airlines, September 2026
American Airlines remains the biggest carrier in the US this month with 21% of the market, operating 21.1m seats. Delta Air Lines and SouthWest Airlines represent 19% and 18% share of the market respectively, with 19m and 18m seats in Sept 26.
Breeze Airways has increased capacity by 46%, 293,700 additional seats, and is 9th largest airline in Sept 26.
Alaska Airlines and Frontier Airlines, fifth and sixth biggest airlines, also increased capacity by 30% and 23% respectively vs last year.
Seat capacity by airline
| Airline | Seats | YoY | |
|---|---|---|---|
| 1. | American Airlines | 21.07m | +5.0% |
| 2. | Delta Air Lines | 18.99m | +1.0% |
| 3. | Southwest Airlines | 17.95m | +0.0% |
| 4. | United Airlines | 17.55m | +5.0% |
| 5. | Alaska Airlines | 6.18m | +30.0% |
| 6. | Frontier Airlines | 3.82m | +23.0% |
| 7. | JetBlue Airways | 3.23m | +14.0% |
| 8. | Allegiant Air | 1.24m | 0.0% |
| 9. | Breeze Airways | 0.93m | +46.0% |
| 10. | Air Canada | 0.67m | +10.0% |
Source: OAG · September 2026 scheduled capacity
Alaska Airlines added the most seats again this month, increasing seats by 1.4m vs Sept 25 - an increase of 30% year on year.
American Airlines added 1m seats to 21.1m and United Airlines added 901,300 seats to 17.6m seats in Sept 26.
Top 10 US airports by seat capacity
The Top 10 busiest airports continue to account for 36.2% of capacity. Atlanta remains the biggest airport in capacity terms, with 5.1m seats. Capacity increased by 5% year on year.
Chicago O'Hare saw the largest increase in capacity again this month, adding 471,100 more seats vs Sept 25 to 4.9m seats.
Charlotte Douglas International and Las Vegas saw capacity fall most within the Top 10 this month, both down by 5% vs last year.
| No | Code | Airport | Seats |
|---|---|---|---|
| 1. | ATL | Atlanta | 5.09m |
| 2. | ORD | Chicago O'Hare | 4.89m |
| 3. | DEN | Denver | 4.21m |
| 4. | DFW | Dallas Fort Worth | 4.19m |
| 5. | LAX | Los Angeles | 3.61m |
| 6. | JFK | New York JFK | 3.07m |
| 7. | SFO | San Francisco | 2.84m |
| 8. | SEA | Seattle-Tacoma | 2.81m |
| 9. | LAS | Las Vegas | 2.58m |
| 10. | CLT | Charlotte Douglas | 2.43m |
Source: OAG September 2026 · hover chart or click a table row to cross-highlight
Top 10 busiest US domestic routes
The busiest route again this month is Los Angeles to San Francisco with 348,100 seats, an increase in capacity of 29% vs Sept 25, 79,000 additional seats
New York La Guardia to Chicago is the second busiest route with 321,400 seats, a 8% increase in capacity year on year.
Boston to Chicago saw growth of over 20% again this month vs Sept 25, with 53,100 additional seats.
Capacity decreased by 18% on the Las Vegas to Los Angeles route, taking it out of the Top 10 domestic routes in Sept 26.
Source: OAG · September 2026 scheduled capacity
States adding and removing most capacity
The state of Illinois continued to see most seat growth this month, with 483,350 additional seats vs Sept 25. Oregon increased capacity at the fastest rate, up 10.8%, followed by Illinois which was up 8.6% vs last year.
Capacity decreased most in the state of New York this month, by 235,300 seats. This was followed by North Carolina with 148,800 fewer seats in Sept 26.
Capacity change by US state — hover for details
- Illinois+483,347 seats (+8.6%)
- California+321,293 seats (+2.8%)
- Oregon+128,546 seats (+10.8%)
- Colorado+107,855 seats (+2.4%)
- Pennsylvania+102,989 seats (+4.5%)
- New York−235,305 seats (−2.8%)
- North Carolina−148,783 seats (−3.9%)
- Michigan−123,192 seats (−5.9%)
- Nevada−120,981 seats (−4.1%)
- Maryland−113,111 seats (−8.2%)
US aviation market: common questions
Data is sourced from OAG's Schedules Analyser.
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Total US scheduled seat capacity in September 2026 is 111.6 million seats, up 0.5% vs September 2025. Domestic capacity increased by 1.0% to 85.9 million seats, while international capacity contracted by 1.0% to 25.6 million seats.