Airline Demand Index
US airline passengers from seats flown, how full flights are and TSA checkpoints · TSA data through · how it is measured
Combined index
Airlines in the combined index:
- Combined demand index
- Combined actual (BTS T-100)
United, Delta, American, JetBlue and Southwest, each weighted by its domestic passengers in the prior full year. The dashed line is the airlines' combined official domestic traffic (BTS T-100); it stops where BTS has not yet published. Hover or tap the chart for each month's figures.
How full US flights are running: see US airline seats, passengers and load factor.
The board: eight airlines, one quarter
Each airline has a page in the Airline Portal with its demand index, capacity against its own guidance and our record. Guidance, report dates and the record are free; the figures fill in with Pro and Pro+.
| Airline | Q4 2026 guide | Tracking (Pro+) | Demand index (Pro) | Month to date (Pro+) | Record | Reports | |
|---|---|---|---|---|---|---|---|
| United Airlines7 hubs | flat to +2%ASMs · last stated | Pro+ | Pro | Pro+ | 0.5 pt misscorr 0.94 | Jan 19in 73 days | Open |
| Delta Air Lines9 hubs | less than 2%seats | Pro+ | Pro | Pro+ | 0.3 pt misscorr 0.91 | Jan 12in 66 days | Open |
| American Airlines7 hubs | +5.5% to +6.5%ASMs | Pro+ | Pro | Pro+ | 0.2 pt misscorr 0.95 | Jan 26in 80 days | Open |
| JetBlue3 hubs | +3% to +4%ASMs | Pro+ | Pro | Pro+ | 0.1 pt misscorr 0.95 | Jan 26in 80 days | Open |
| Southwest Airlines11 hubs | +3% to +4%ASMs | Pro+ | Pro | Pro+ | <0.1 pt misscorr 0.92 | Jan 27in 81 days | Open |
| Alaska Air Groupcapacity-led | +1% to +1.5%ASMs | Pro+ | Pro | Pro+ | 0.1 pt misscorr 0.85 | Jan 21in 75 days | Open |
| Frontier Airlinescapacity-led | +5% to +6%ASMs | Pro+ | Pro | Pro+ | <0.1 pt misscorr 0.89 | Feb 10in 95 days | Open |
| Allegiant and Sun Countrycapacity-led | about +0%ASMs | Pro+ | Pro | Pro+ | 0.4 pt misscorr 0.91 | Feb 3in 88 days | Open |
Q4 2026, day 38 of 92. Record = average gap between our capacity read and the reported figure; corr = Demand Index against the airline's BTS T-100 domestic passengers.
Reporting calendar, Q4 2026
- Delta · Jan 12, 2027
- United · Jan 19, 2027
- Alaska · Jan 21, 2027
- American · Jan 26, 2027
- JetBlue · Jan 26, 2027
- Southwest · Jan 27, 2027
- Allegiant · Feb 3, 2027
- Frontier · Feb 10, 2027
Expected dates follow last year's release dates. Each airline's page opens its quarter to Pro the day after that airline reports; Pro+ sees them all now.
By airline
Show: UnitedDeltaAmericanJetBlueSouthwestAlaskaFrontierAllegiant
- United index
- United actual (BTS T-100)
Each airline's own demand index against its official traffic, month by month, the latest readings side by side, and a choice of which airlines go into the combined index are in the Pro plan. See plans · Sign in
The Airline Demand Index tracks monthly domestic passengers for United, Delta, American, JetBlue and Southwest, and seat capacity for Alaska, Frontier and Allegiant (with Sun Country). The official count of airline passengers is BTS T-100: the US Department of Transportation's Bureau of Transportation Statistics compiles every US airline's monthly report of passengers carried on each route. BTS publishes it on a lag of about three months, so its latest figures are for July 2026 while the TSA data here runs to October 31, 2026. The Airline Demand Index reads the same trend from faster sources: the seats on the flights each airline actually flew, which Passenger Index counts the next morning, how full US flights are running nationally (TSA's daily checkpoint count against every airline's seats), and TSA screenings at the airline's hubs, which TSA releases weekly. So it gives a near-real-time look at where airline traffic is heading.
Combined, the five airlines' domestic passengers were roughly flat (+0.5%) year over year in September 2026 and roughly flat (+0.4%) in October 1–31, 2026. Over August 2023 to July 2026 the combined index tracked the official figure with a correlation of 0.94, missing by 1.2 points a month on average.
Combined index, month by month
| Month | Demand index | Actual (BTS T-100) |
|---|---|---|
| October 1–31, 2026 (to date, TSA only) | +0.4% | – |
| Sep 2026 (TSA only) | +0.5% | – |
| Aug 2026 | -1.8% | – |
| Jul 2026 | -0.1% | +1.3% |
| Jun 2026 | +1.0% | +2.4% |
| May 2026 | +1.4% | +2.6% |
| Apr 2026 | +0.8% | +1.6% |
| Mar 2026 | +2.2% | +2.9% |
| Feb 2026 | +3.2% | +3.6% |
| Jan 2026 | +0.8% | -0.7% |
| Dec 2025 | +0.2% | -1.9% |
| Oct 2025 | +3.4% | +2.9% |
Show earlier months (Aug 2023 to Sep 2025)
| Month | Demand index | Actual (BTS T-100) |
|---|---|---|
| Sep 2025 | +0.9% | +0.3% |
| Aug 2025 | +0.8% | -0.0% |
| Jul 2025 | +1.5% | +0.7% |
| Jun 2025 | -0.8% | -1.4% |
| May 2025 | -1.9% | -2.5% |
| Apr 2025 | -0.9% | -2.6% |
| Mar 2025 | -1.9% | -3.3% |
| Feb 2025 | -2.8% | -6.7% |
| Jan 2025 | +0.4% | -2.4% |
| Dec 2024 | +5.6% | +4.0% |
| Oct 2024 | +0.3% | -0.9% |
| Sep 2024 | +0.9% | +0.3% |
| Aug 2024 | +3.1% | +2.2% |
| Jul 2024 | +3.0% | +2.0% |
| Jun 2024 | +4.2% | +4.6% |
| May 2024 | +6.3% | +5.3% |
| Apr 2024 | +4.5% | +4.5% |
| Mar 2024 | +6.8% | +5.5% |
| Feb 2024 | +7.9% | +8.5% |
| Jan 2024 | +4.8% | +3.6% |
| Dec 2023 | +8.1% | +8.9% |
| Oct 2023 | +9.5% | +7.2% |
| Sep 2023 | +8.6% | +6.2% |
| Aug 2023 | +10.3% | +8.2% |
Download the combined index as CSV (CC BY 4.0) · Markdown version
How well each airline's index tracks
| Airline | Hubs / main airports | Correlation | Avg miss (pts) |
|---|---|---|---|
| United Airlines | DEN, ORD, IAH, EWR, SFO, IAD, LAX | 0.94 | 1.4 |
| Delta Air Lines | ATL, MSP, DTW, SLC, JFK, LGA, LAX, SEA, BOS | 0.91 | 1.6 |
| American Airlines | DFW, CLT, ORD, MIA, PHX, PHL, DCA | 0.95 | 1.3 |
| JetBlue | BOS, JFK, FLL | 0.95 | 2.2 |
| Southwest Airlines | DEN, LAS, BWI, PHX, DAL, BNA, MCO, HOU, STL, AUS, SAN | 0.92 | 2.2 |
| Alaska Air Group | SEA, HNL, PDX, OGG, ANC, KOA, LIH | 0.85 | 2.3 |
| Frontier Airlines | DEN, MCO, ATL, LAS, PHL, TPA, CLE, SJU | 0.89 | 6.1 |
| Allegiant and Sun Country | MSP, SFB, PIE, PGD | 0.91 | 2.6 |
How it is measured
Each month's figure blends two reads of the airline's domestic passengers, year over year. Six tenths is the change in seats on all the airline's domestic flights (mainline plus its own regional brands), adjusted by the change in how full US domestic flights are nationally. Seats come from BTS T-100 for the months BTS has published; before that from BTS's on-time flight records and Passenger Index flight activity data (air traffic flight messages), with seats for each aircraft type from T-100. How full flights are is TSA's national daily checkpoint count against every airline's domestic seats, compared with the same month a year earlier and corrected by half its average miss against BTS over the latest 12 published months. Four tenths is the change in passengers screened at TSA checkpoints at the airline's hubs, from TSA's checkpoint throughput files (FOIA): where an airline has its own terminal, only that terminal's checkpoints are counted, elsewhere the whole airport is, and days a checkpoint reported only partly are dropped; hubs are weighted by the airline's domestic passengers boarding there in the prior full year. The actual figure is the airline's domestic boardings on all its flights from BTS T-100, which BTS publishes about three months after the month ends. The current month compares the days so far with the same weekdays a year earlier. The backtest uses T-100 seats for every month and the national estimate of how full flights were; the seat estimates used for the newest months matched T-100 within about half a point for most airlines when checked on July 2026. Until November 2026 the index read seats and TSA at the hubs only, compared with boardings at the hubs; the change tracks what airlines report better.
The seat side assumes each airline's planes fill like the industry's, and the TSA side at its hubs is what shows an airline-specific change; TSA in turn misses connecting passengers and can't tell domestic from international departures, while the official figure is domestic only. For Alaska, Frontier and Allegiant the figure is seat growth alone: The figure is the change in seats on all the airline's domestic flights, year over year: a capacity-led read of its traffic. Seats come from BTS T-100 for the months BTS has published; before that from BTS's on-time flight records and Passenger Index flight activity data (air traffic flight messages), with seats for each aircraft type from T-100, each day against the same weekday a year earlier. TSA checkpoint counts at the airline's main airports and the national change in how full flights are were both tested and did not improve it: other airlines share those checkpoints, and this airline's planes fill on their own pattern. The actual figure is the airline's domestic boardings on all its flights from BTS T-100, which BTS publishes about three months after the month ends. Each airline's page lists its airports and what the index misses.
Months marked TSA only have no seat data yet and are read from TSA screenings alone until BTS posts its flight records, about six weeks after the month ends.
Cite as: Passenger Index, "Airline Demand Index", https://passengerindex.com/web/airlines/ (CC BY 4.0).
Frequently asked questions
What is the Airline Demand Index?
The Airline Demand Index tracks monthly domestic passengers for United, Delta, American, JetBlue and Southwest, and seat capacity for Alaska, Frontier and Allegiant (with Sun Country). The official count of airline passengers is BTS T-100: the US Department of Transportation's Bureau of Transportation Statistics compiles every US airline's monthly report of passengers carried on each route. BTS publishes it on a lag of about three months, so its latest figures are for July 2026 while the TSA data here runs to October 31, 2026. The Airline Demand Index reads the same trend from faster sources: the seats on the flights each airline actually flew, which Passenger Index counts the next morning, how full US flights are running nationally (TSA's daily checkpoint count against every airline's seats), and TSA screenings at the airline's hubs, which TSA releases weekly. So it gives a near-real-time look at where airline traffic is heading. Combined, the five airlines' domestic passengers were roughly flat (+0.5%) year over year in September 2026 and roughly flat (+0.4%) in October 1–31, 2026. Over August 2023 to July 2026 the combined index tracked the official figure with a correlation of 0.94, missing by 1.2 points a month on average.
What is BTS T-100?
The official count of airline passengers is BTS T-100: the US Department of Transportation's Bureau of Transportation Statistics compiles every US airline's monthly report of passengers carried on each route. BTS publishes it on a lag of about three months, so its latest figures are for July 2026 while the TSA data here runs to October 31, 2026. The Airline Demand Index reads the same trend from faster sources: the seats on the flights each airline actually flew, which Passenger Index counts the next morning, how full US flights are running nationally (TSA's daily checkpoint count against every airline's seats), and TSA screenings at the airline's hubs, which TSA releases weekly. So it gives a near-real-time look at where airline traffic is heading.
Can I see each airline's index on its own?
Yes, in the Passenger Index Pro plan (https://passengerindex.com/web/plans/): United, Delta, American, JetBlue, Southwest, Alaska, Frontier and Allegiant each have a monthly demand index with the official BTS T-100 figure beside it. This page's combined index is free.
How is the combined index weighted?
It combines the five airlines whose index reads passengers (United, Delta, American, JetBlue and Southwest), each counted by its domestic passengers in the prior full year (BTS T-100). The combined actual figure adds up the five airlines' domestic boardings. Alaska, Frontier and Allegiant are capacity-led reads and are left out of the combined figure.
How often is it updated?
The seat side updates daily from flight activity and monthly from BTS; the TSA side when TSA releases new checkpoint data, usually weekly; the official BTS T-100 figures are added monthly. This edition uses TSA data through October 31, 2026 and BTS T-100 through July 2026.