Airports › Ontario (ONT) › May 2026
Airport month · May 2026
Ontario International in May 2026
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.
In May 2026, reporting carriers scheduled 2,298 domestic departures from Ontario International (ONT). 78.6% left less than 15 minutes late and 79.3% reached their destination on time; 0.7% were cancelled.
Nationally that month, 77.1% of flights departed on time and 77.6% arrived on time, so ONT departures were 1.5 points above the national departure figure.
A year earlier, in May 2025, the airport had 2,340 departures with 82.4% leaving on time: a change of −3.8 points, with flights down 2%.
Flights arriving at ONT that month were on time 76.4% of the time (2,297 scheduled arrivals).
Of the delay minutes that carriers assigned to a BTS cause category that month, late-arriving aircraft 43%, air carrier 29% and national aviation system 28%.
- On time 79.3%
- Arrived 15+ minutes late 19.8%
- Cancelled 0.7%
- Diverted 0.1%
May 2026 against a year earlier, the airport's year and the nation
| Measure | May 2026 | May 2025 | ONT, 12 months to Jul 2026 | All reported flights, May 2026 |
|---|---|---|---|---|
| Departed on time | 78.6% | 82.4% | 80.3% | 77.1% |
| Arrived on time | 79.3% | 82.3% | 81.2% | 77.6% |
| Cancelled | 0.7% | 0.6% | 0.9% | 0.9% |
| Average departure delay (late minutes only) | 13.0 min | 13.6 min | 13.7 min | 16.0 min |
| Scheduled departures a day | 77 | 78 | 71 | 20,391 |
| Scheduled departures | 2,298 | 2,340 | 25,854 | 611,735 |
Airlines that month
| Reporting carrier | Flights | Share | On time | Avg arrival delay | Cancelled |
|---|---|---|---|---|---|
| WN Southwest Airlines | 992 | 43% | 75.4% | 5.8 min | 0.3% |
| AA American Airlines | 291 | 13% | 83.8% | -3.3 min | 2.4% |
| UA United Airlines | 228 | 10% | 72.8% | 9.8 min | 0.0% |
| F9 Frontier Airlines | 209 | 9% | 75.1% | 12.3 min | 0.5% |
| OO SkyWest Airlines | 186 | 8% | 87.6% | -6.8 min | 0.5% |
| AS Alaska Airlines | 178 | 8% | 87.1% | -4.5 min | 1.1% |
| DL Delta Air Lines | 175 | 8% | 90.3% | -7.7 min | 1.1% |
| MQ Envoy Air | 21 | 1% | 81.0% | 0.8 min | 0.0% |
| B6 JetBlue Airways | 18 | 1% | 83.3% | 27.2 min | 0.0% |
Busiest routes that month
| Route | Cities | Flights | On time | Avg arrival delay | Cancelled |
|---|---|---|---|---|---|
| ONT–PHX | Ontario to Phoenix | 254 | 87.8% | -2.2 min | 0.0% |
| ONT–SEA | Ontario to Seattle | 249 | 88.4% | -3.2 min | 0.8% |
| ONT–DEN | Ontario to Denver | 242 | 83.9% | 2.1 min | 0.0% |
| ONT–LAS | Ontario to Las Vegas | 199 | 64.3% | 13.3 min | 0.0% |
| ONT–DFW | Ontario to Dallas/Fort Worth | 197 | 78.2% | 1.3 min | 3.6% |
| ONT–SMF | Ontario to Sacramento | 187 | 79.1% | 1.8 min | 0.5% |
| ONT–SFO | Ontario to San Francisco | 127 | 42.5% | 33.3 min | 1.6% |
| ONT–OAK | Ontario to Oakland | 118 | 80.5% | 3.4 min | 0.0% |
| ONT–SLC | Ontario to Salt Lake City | 115 | 95.7% | -11.9 min | 0.9% |
| ONT–SJC | Ontario to San Jose | 110 | 91.8% | -5.4 min | 0.0% |
| ONT–ATL | Ontario to Atlanta | 93 | 86.0% | -2.8 min | 1.1% |
| ONT–IAH | Ontario to Houston | 61 | 83.6% | 4.4 min | 0.0% |
By scheduled departure hour
Delay causes
Questions and answers
How many flights left ONT on time in May 2026?
78.6% of 2,298 scheduled domestic departures left less than 15 minutes late, and 79.3% reached their destination on time. The national figures that month were 77.1% and 77.6%.
How does that compare with a year earlier?
In May 2025, 82.4% of 2,340 departures left on time and 0.6% were cancelled, against 78.6% and 0.7% in May 2026.
Provenance
Source: Bureau of Transportation Statistics, Reporting Carrier On-Time Performance, file for May 2026; public domain. Domestic scheduled flights by reporting carriers, totals and averages only. The site's data runs through July 2026. Full record for ONT · methodology · corrections.