This is one month of data, looked at carefully: how often flights on US routes arrived on time in July 2026. It is a description of what happened in that month, not a forecast and not a verdict on any airline.
The short version
- Across all 630,535 flights in the data, 69.4% arrived on time.
- Among routes with at least 300 flights, the best were Hawaii inter-island routes and routes out of Los Angeles, led by Lihue to Honolulu at 87.5%.
- The weakest were mostly routes into San Francisco: eight of the ten lowest ended there, and Seattle to San Francisco was lowest at 34.7%.
- Late-arriving aircraft and the airline’s own causes accounted for most of the delay minutes BTS attributes.
Where the data comes from and how we counted
The figures come from the US Department of Transportation’s Bureau of Transportation Statistics (BTS) on-time performance reports, which US reporting airlines file by route, as loaded by BookWithAI. The same data feeds the on-time figure BookWithAI shows for US flights; how it is built is described on the methodology page.
- On time means the flight did not arrive 15 minutes or more late. Cancelled and diverted flights count as not on time. So “on-time share” is the share of scheduled flights that arrived less than 15 minutes late, and the rest were late, cancelled or diverted.
- A route here is a directional airport pair, such as Los Angeles to San Francisco, with all airlines combined. The route’s share is weighted by flights, so an airline that flew more of the route counts for more. Los Angeles to San Francisco and San Francisco to Los Angeles are separate routes.
- A flight-count floor. A route is ranked only if it has at least 300 flights in the month, so that a handful of flights cannot put a route at the top or bottom. That leaves 409 of the 5,901 routes in the data, covering 183,039 of the 630,535 flights. Most routes in the data are thinly flown, and they are not ranked.
- Small carrier-route-months are missing. BookWithAI keeps a carrier on a route for a month only if it has at least 5 flights, so the totals here are slightly below the full BTS count.
The routes that ran on time most often
| Route | On-time share | Flights | Airlines on the route |
|---|---|---|---|
| LIH to HNL | 87.5% | 664 | Alaska Airlines, Southwest Airlines |
| OGG to HNL | 87.2% | 803 | Alaska Airlines, Southwest Airlines |
| HNL to OGG | 86.9% | 803 | Alaska Airlines, Southwest Airlines |
| LAX to PDX | 84.9% | 351 | Alaska Airlines, Delta Air Lines, Frontier Airlines, SkyWest Airlines |
| LAX to SMF | 84.6% | 518 | Delta Air Lines, Frontier Airlines, SkyWest Airlines, Southwest Airlines |
| HNL to LIH | 84.2% | 664 | Alaska Airlines, Southwest Airlines |
| HNL to KOA | 84.1% | 598 | Alaska Airlines, Southwest Airlines |
| LAX to SLC | 83.3% | 336 | Delta Air Lines, Frontier Airlines, SkyWest Airlines, Southwest Airlines |
| LAX to IAH | 83.1% | 414 | Delta Air Lines, Frontier Airlines, SkyWest Airlines, United Airlines |
| ANC to SEA | 83.1% | 721 | Alaska Airlines, Delta Air Lines |
Five of the ten are short Hawaii inter-island routes, four start at Los Angeles, and one is Anchorage to Seattle. The data records how often flights arrived on time, not why these routes did well, and we do not claim a reason.
The routes that ran on time least often
| Route | On-time share | Flights | Airlines on the route |
|---|---|---|---|
| SEA to SFO | 34.7% | 666 | Alaska Airlines, Delta Air Lines, SkyWest Airlines, United Airlines |
| SAN to SFO | 38.1% | 659 | Alaska Airlines, Frontier Airlines, SkyWest Airlines, United Airlines, Southwest Airlines |
| LAS to SFO | 39.3% | 549 | Alaska Airlines, Frontier Airlines, United Airlines, Southwest Airlines |
| PHX to SFO | 43.1% | 404 | American Airlines, Frontier Airlines, SkyWest Airlines, United Airlines, Southwest Airlines |
| DEN to SFO | 43.8% | 514 | Frontier Airlines, United Airlines, Southwest Airlines |
| SNA to SFO | 44.1% | 404 | Alaska Airlines, Frontier Airlines, SkyWest Airlines, United Airlines |
| LAX to SFO | 44.3% | 1,118 | American Airlines, Alaska Airlines, Delta Air Lines, Frontier Airlines, SkyWest Airlines, United Airlines, Southwest Airlines |
| DFW to SFO | 45.5% | 422 | American Airlines, Frontier Airlines, United Airlines |
| JFK to SJU | 47.7% | 310 | JetBlue, Delta Air Lines |
| DFW to BNA | 48.3% | 325 | American Airlines, Frontier Airlines, Envoy Air, PSA Airlines |
Eight of these ten end at San Francisco. That is what the numbers show for July 2026; they do not say why, and one month cannot say whether it is typical. Note too that Los Angeles to San Francisco is flown by seven airlines in this table, so its figure is not any one airline’s record.
Airlines, overall
| Airline (code) | On-time share | Flights | Routes flown |
|---|---|---|---|
| Envoy Air (MQ) | 79.9% | 29,620 | 478 |
| Alaska Airlines (AS) | 75.9% | 31,674 | 406 |
| SkyWest Airlines (OO) | 74.6% | 76,930 | 1,173 |
| Delta Air Lines (DL) | 71.9% | 94,060 | 910 |
| United Airlines (UA) | 71.5% | 74,318 | 835 |
| Allegiant Air (G4) | 68.6% | 13,238 | 967 |
| Republic Airways (YX) | 68.0% | 31,767 | 466 |
| Southwest Airlines (WN) | 68.0% | 124,640 | 1,576 |
| American Airlines (AA) | 65.0% | 89,120 | 880 |
| Frontier Airlines (F9) | 62.5% | 20,462 | 522 |
| PSA Airlines (OH) | 59.0% | 21,394 | 368 |
| JetBlue (B6) | 55.7% | 23,312 | 359 |
These are each airline’s share across the routes it flew in this data, so they are shaped by where each airline flies. An airline whose network is mostly short regional hops and one whose network is mostly busy trunk routes are not facing the same month, and a difference of a few points between two airlines is within what one month of data can move. Envoy Air, SkyWest, Republic and PSA are regional airlines that fly under the American, Delta, United and (for SkyWest) Alaska brands, so a flight sold under those names may appear under a regional code here.
What delayed the flights that arrived late
BTS also records the minutes of delay for flights that arrived 15 minutes or more late, split into five reported causes. These are shares of those minutes in the data, not shares of flights.
| BTS delay cause | Share of delay minutes |
|---|---|
| Late-arriving aircraft | 41.8% |
| Air carrier | 31.7% |
| National Aviation System (NAS) | 19.9% |
| Extreme weather | 6.4% |
| Security | 0.1% |
- Late-arriving aircraft is delay passed on because the aircraft’s earlier flight arrived late.
- Air carrier covers causes within the airline’s control, such as crew, cleaning or baggage loading.
- NAS is the National Aviation System: airport operations, heavy traffic and air traffic control.
- Weather is BTS’s category for extreme or hazardous weather. Milder weather delays are generally reported under NAS, so this row is not the share of delay minutes that weather played any part in.
These are the categories as reported; we draw no conclusion about what caused any one route’s result.
What this does not tell you
- It is one month. July 2026 only. Nothing here shows that a route or airline is reliably good or bad, or that any month is typical, and none of it is a prediction of a future month.
- Coverage is US reporting airlines. BTS data covers the US airlines that must report, here 12 of them. The carriers shown are the ones that report in this BTS file; we have not added or inferred any others. It does not cover flights by airlines that do not report, or most flights outside the US.
- A route is not your flight. A route’s share blends every airline, time of day and day of the month. The flight you are choosing can do better or worse than its route.
- Counting rules matter. Because cancelled and diverted flights count as not on time, a route’s figure mixes late arrivals with cancellations.
For how to use on-time data when you choose a flight, see how to judge whether a flight will actually be on time. BookWithAI does not book flights; it shows an on-time figure for US flights from this same BTS data and sends you to Google Flights to choose a seller.
You can also read what BookWithAI can and cannot tell you about a route.