Flying Got Worse Outside Summer

Summary

On-time arrival across all US flights in the DOT data was 79.4% in the twelve months to July 2024, 79.3% in the twelve months to July 2025 and 77.6% in the twelve months to July 2026, and the share of flights cancelled ran from 1.26% to 1.82%. Summer ended where it began: Jun–Aug ran 74.5%, 73.1%, 74.4% in the three years. The decline is in the other seasons: winter lost 4.1 points and fall lost 3.3 points. 51 of the 64 covered airports are lower than they were two years earlier, but they mostly kept their order.

The data runs through July 2026. It is cut into three windows of 12 months that end in that month: Aug 2023–Jul 2024, Aug 2024–Jul 2025 and Aug 2025–Jul 2026. Every window holds each calendar month once, so a window is never a summer set against a winter. Months before the first window are not used. Seasons are the usual calendar quarters of the year, fall Sep–Nov, winter Dec–Feb, spring Mar–May and summer Jun–Aug. The figures come from the monthly tables FlyerIntel builds from the DOT records of every flight by scheduled origin and month. On-time arrival is the share of flights that arrived fewer than 15 minutes late among those that reached their destination, and cancelled and diverted flights are outside it, so the cancellation rate is given beside it and once as one figure with the two combined.

Every flight in the DOT data, counted at its scheduled origin airport. A row that is a share has at least 120 flights behind it in every window.

Summer (Jun–Aug) is the worst season for on-time arrival and it stayed put: 74.5%, 73.1%, 74.4%. The drop in the network is the drop in the rest of the year. Winter (Dec–Feb) lost 4.1 points and fall (Sep–Nov) lost 3.3 points, and spring (Mar–May) moved +0.2. The slide is not the same shape everywhere: fall (Sep–Nov) ran 84.1%, 85.6%, 80.8%, level or higher in the middle window and lower in the last; winter (Dec–Feb) ran 81.5%, 79.7%, 77.4%, lower in each window. Cancellations followed: fall 0.58% to 1.17%, winter 1.57% to 2.82%, spring 0.98% to 1.58% and summer 1.92% to 1.79%. The best month of each window fell from 86.4% to 83.4%, while the worst month, July, ran 70.4%, 71.1%, 71.7%.

Months pooled by season within each window. Every season holds at least 120 flights in each window.

The same calendar month in each of the three windows.

Airlines code each late flight's delay minutes to one of five causes, and the codes are the airlines' own. Per completed flight, coded minutes rose from 14.7 to 16.2. National Aviation System rose most, 2.7 to 3.4 minutes, 45% of the rise. Among the seasons that dropped, the largest rise was air carrier in winter (Dec–Feb), up 1.5 minutes per flight; national aviation system in fall (Sep–Nov), up 1.4 minutes per flight. The National Aviation System code covers a broad set of conditions the airline does not control, such as airport operations, heavy traffic, air traffic control and weather that is not extreme. The codes describe how airlines filed the delay and not who was at fault, and a cause is coded only for flights that arrived 15 or more minutes late.

Sorted by the size of the rise. A negative share means a cause that fell while the total rose.

Coded minutes are the five cause codes added together.

51 of the 64 covered airports have a lower on-time rate in the last window than in the first. Between the first window and the second 27 fell, and between the second and the last 51. The largest falls are LGA (New York) -8.6, DCA (Washington) -8.1, ORD (Chicago) -5.2, DTW (Detroit) -5.1 and ABE (Allentown) -5.0 points; the largest rises SJU (San Juan) +4.2, BWI (Baltimore) +3.9, CLT (Charlotte) +2.7, IAH (Houston) +2.6 and ANC (Anchorage) +2.4. Ranked by on-time rate, the airports of the first window and of the last are in much the same order (rank correlation 0.80). A bad year moved every airport down together and did not reshuffle them. A move is named only when both windows hold at least 500 flights and the change is 5 standard errors wide.

Departures from the airport, as on the airport pages. Ordered from the largest fall to the largest rise in on-time arrival.

12 airlines reported every month of all three windows with at least 10,000 flights in each. Endeavor Air, Hawaiian Airlines and Spirit Airlines did not and are left out. Republic Airways lost 8.7 points and its cancellations rose 2.2 and PSA Airlines lost 6.1 points and its cancellations rose 2.8. Frontier Airlines gained 2.1 points and Envoy Air gained 2.0 points. An airline’s figures are for all the flights it operated, so a regional carrier’s are for the flights it flew for its partners.

Airlines that reported every month of the three windows. Ordered from the largest fall to the largest rise.

The network figure could fall because airlines shifted flying toward routes that run late. To check, the same routes are followed through the three windows. 4,777 routes had at least 120 completed flights in each, together 97% of the first window's flights. Weighting each by its flights in the first window, so that the mix of routes cannot change, on-time arrival went from 79.3% to 79.4% to 77.7%. That is a fall of 1.6 points, against 1.7 for the whole network.

The DOT data says what happened and not why. A drop of this size can come from air traffic control staffing, weather, airline operations or a shortage of aircraft or crews, and the cause codes filed by the airlines cannot tell them apart. Three years hold three of each season, so a single fall or winter that went badly moves a season’s figure a great deal; the drop in fall is a change between two windows and not a trend of several years. The windows are twelve months that end in the latest month, so they will move as new months arrive, and the seasonal figures move with them. The airport figures cover the airports FlyerIntel profiles. Airlines that did not report every month are not compared.