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Airport · 12 months to July 2026
Ontario International: delays and on-time record
Ontario, California
BTS: A flight is counted as on time if it arrived less than 15 minutes after its scheduled time. Only carriers with at least 0.5 percent of domestic scheduled passenger revenue report. Data through July 2026; this is a monthly history, not live airport status.
Ontario International (ONT) in Ontario, California had 25,854 scheduled domestic departures by reporting carriers in the 12 months to July 2026, about 71 a day, on 25 routes.
80.3% of those flights left the gate less than 15 minutes late, 4.2 points above the national departure figure of 76.1%. Flights arriving at ONT were on time 77.1% of the time, 1.1 points above the national arrival figure of 76.0%.
0.9% of scheduled departures were cancelled (national: 1.8%), and the average departure delay, counting early and on-time departures as zero, was 13.7 min.
Southwest Airlines is the largest reporting carrier at ONT with 45% of departures. Among carriers with at least 259 departures, Delta Air Lines had the highest on-time arrival share for its ONT departures (88.8%) and Frontier Airlines the lowest (74.5%).
On-time departures are down 3.6 points on the previous 12 months (83.9%).
Of the delay minutes that carriers assigned to a BTS cause category for flights leaving ONT, late-arriving aircraft 43%, air carrier 34% and national aviation system 21%.
- On time 81.2%
- Arrived 15+ minutes late 17.7%
- Cancelled 0.9%
- Diverted 0.2%
As origin and as destination, against the nation
| Measure | Departures from ONT | Arrivals at ONT | All reported flights | ONT departures, previous 12 months |
|---|---|---|---|---|
| Departed on time (less than 15 min late) | 80.3% | 73.8% | 76.1% | 83.9% |
| Arrived on time | 81.2% | 77.1% | 76.0% | 84.1% |
| Cancelled | 0.9% | 0.8% | 1.8% | 0.7% |
| Diverted | 0.2% | 0.1% | 0.3% | 0.2% |
| Average departure delay (late minutes only) | 13.7 min | 15.3 min | 17.4 min | 11.5 min |
| Arrival delay minutes per 100 flights | 1,296 | 1,345 | 1,684 | 1,107 |
| Scheduled flights | 25,854 | 25,849 | 7,043,858 | 26,576 |
12 months to July 2026. The first column follows flights that left ONT; the second follows flights that landed there. Year on year, on-time departures moved −3.6 pts.
Airlines at ONT
| Reporting carrier | Flights | Share | On time | Avg arrival delay | Cancelled |
|---|---|---|---|---|---|
| WN Southwest Airlines | 11,662 | 45% | 80.9% | 2.9 min | 0.4% |
| AA American Airlines | 3,608 | 14% | 80.1% | 9.1 min | 2.0% |
| UA United Airlines | 2,460 | 10% | 79.0% | 7.3 min | 0.5% |
| F9 Frontier Airlines | 2,258 | 9% | 74.5% | 10.1 min | 1.3% |
| AS Alaska Airlines | 2,067 | 8% | 83.6% | -0.8 min | 1.4% |
| DL Delta Air Lines | 1,865 | 7% | 88.8% | -3.6 min | 1.4% |
| OO SkyWest Airlines | 1,724 | 7% | 87.1% | -2.1 min | 0.4% |
| B6 JetBlue Airways | 165 | 1% | 69.1% | 47.1 min | 1.8% |
| MQ Envoy Air | 45 | 0% | 88.9% | -3.9 min | 0.0% |
Departures from ONT by reporting carrier, ordered by flights; on time means the flight reached its destination less than 15 minutes late. Green is at or above the airport's overall share of 81.2%. Carriers fly different routes at different hours, so the rows are not a like-for-like test.
Busiest routes from ONT
| Route | Cities | Flights | On time | Avg arrival delay | Cancelled |
|---|---|---|---|---|---|
| ONT–PHX | Ontario to Phoenix | 3,027 | 82.0% | 5.6 min | 0.6% |
| ONT–DEN | Ontario to Denver | 2,643 | 80.6% | 5.7 min | 0.3% |
| ONT–SEA | Ontario to Seattle | 2,505 | 85.3% | -1.3 min | 1.1% |
| ONT–LAS | Ontario to Las Vegas | 2,476 | 76.3% | 7.2 min | 0.9% |
| ONT–DFW | Ontario to Dallas/Fort Worth | 2,297 | 76.5% | 11.1 min | 2.7% |
| ONT–SMF | Ontario to Sacramento | 2,114 | 85.3% | -1.6 min | 0.3% |
| ONT–OAK | Ontario to Oakland | 1,471 | 86.1% | -2.4 min | 0.4% |
| ONT–SJC | Ontario to San Jose | 1,319 | 85.4% | -0.7 min | 0.1% |
| ONT–SFO | Ontario to San Francisco | 1,309 | 61.7% | 19.3 min | 0.8% |
| ONT–SLC | Ontario to Salt Lake City | 1,239 | 90.7% | -5.7 min | 0.9% |
| ONT–ATL | Ontario to Atlanta | 937 | 86.8% | -0.8 min | 1.8% |
| ONT–PDX | Ontario to Portland | 565 | 89.6% | -6.3 min | 0.7% |
| ONT–IAH | Ontario to Houston | 561 | 84.3% | 4.8 min | 1.1% |
| ONT–HNL | Ontario to Honolulu | 423 | 86.5% | -2.5 min | 0.2% |
| ONT–DAL | Ontario to Dallas | 399 | 72.9% | 10.7 min | 1.5% |
| ONT–HOU | Ontario to Houston | 362 | 65.2% | 13.7 min | 0.0% |
| ONT–MDW | Ontario to Chicago | 360 | 89.4% | -3.2 min | 0.3% |
| ONT–AUS | Ontario to Austin | 337 | 73.9% | 8.5 min | 0.3% |
| ONT–BNA | Ontario to Nashville | 336 | 76.5% | 7.3 min | 0.6% |
| ONT–CLT | Ontario to Charlotte | 327 | 85.3% | -1.0 min | 1.2% |
| ONT–ORD | Ontario to Chicago | 291 | 78.4% | 8.1 min | 1.4% |
| ONT–BWI | Ontario to Baltimore | 281 | 83.6% | 1.0 min | 0.4% |
| ONT–JFK | Ontario to New York | 165 | 69.1% | 47.1 min | 1.8% |
The 23 busiest of 25 routes with reported flights. Routes with at least 10 flights a month have their own page.
Month by month
By scheduled departure hour
Among hours with at least 517 departures, 5 am to 6 am had the highest on-time share (94.3% of 1,565 flights) and 8 pm to 9 pm the lowest (63.5% of 672).
Delay causes
Cancellations by reported reason (225 in the period): air carrier 45%, weather 40%, national aviation system 16%, security 0%.
Checkpoint volumes
TSA publishes daily checkpoint passenger counts for the country as a whole, not for ONT on its own. The national series through September 2026 is on the checkpoint volumes page.
Questions and answers
How often do flights leave ONT on time?
80.3% of the 25,854 scheduled domestic departures in the 12 months to July 2026 left less than 15 minutes late; the national figure was 76.1%. 0.9% were cancelled.
How often do flights arrive at ONT on time?
77.1% of 25,849 scheduled arrivals were on time by the BTS definition, against 76.0% nationally.
Which airline has the highest on-time share at ONT?
Counting departures from ONT and whether they reached their destination on time, Delta Air Lines had the highest share (88.8% of 1,865 flights), then SkyWest Airlines (87.1%) and Alaska Airlines (83.6%). Carriers fly different routes at different hours, so the figures are not a like-for-like test.
What causes delays at ONT?
For departures from ONT that reached their destination 15 or more minutes late, carriers attributed the delay minutes as follows: late-arriving aircraft 43%, air carrier 34%, national aviation system 21%, extreme weather 2%, security 0%.
What time of day has the highest on-time share at ONT?
Departures scheduled from 5 am to 6 am local time left on time 94.3% of the time, the highest of any hour with enough flights to compare; 8 pm to 9 pm was lowest at 63.5%.
Is it getting better?
On-time departures for the 12 months to July 2026 were 80.3%, down 3.6 points on the previous 12 months (83.9%). The monthly chart shows each of the last 36 months, and each month has its own page.
Does this page show today's delays at ONT?
No. BTS publishes on-time records about two months after the month ends, so this page is a monthly history through July 2026. For live conditions use the FAA airport status service or your airline.
Provenance
Source: Bureau of Transportation Statistics, Reporting Carrier On-Time Performance (1987 to present), monthly files August 2023 to July 2026; airport name from the BTS airport lookup table. US government works in the public domain. Domestic scheduled flights by reporting carriers only: international flights, charters and smaller carriers are not in the source. Totals and averages only; no individual flight or aircraft is identified. See the methodology; report processing errors through corrections.