Routes › Ontario (ONT) › ONT to ORD
Route · 12 months to July 2026
Ontario to Chicago: on-time record
Ontario International to Chicago O'Hare International
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 flight status.
78.4% of scheduled ONT to ORD flights arrived on time in the 12 months to July 2026. The figure covers 291 flights between Ontario and Chicago by carriers that report to BTS, a distance of 1,700 miles.
That is 2.4 points above the national on-time share of 76.0% for the same period and 2.8 points below the 81.2% recorded for all departures from ONT. Flights that did arrive were 8.1 min late on average, and 1.4% of scheduled flights were cancelled (national: 1.8%).
United Airlines is the only reporting carrier on the route, with 291 flights in the period.
By scheduled departure hour (local time at ONT), flights leaving from 6 am to 7 am had the highest on-time share, 81.9%; those leaving from 11 pm to 12 am had the lowest, 76.7%.
Of the delay minutes that carriers assigned to a BTS cause category on this route, air carrier 49%, national aviation system 37% and late-arriving aircraft 15%.
- On time 78.4%
- Arrived 15+ minutes late 18.9%
- Cancelled 1.4%
- Diverted 1.4%
Airlines on the route compared
| Reporting carrier | Flights | Share | On time | Avg arrival delay | Cancelled |
|---|---|---|---|---|---|
| UA United Airlines | 291 | 100% | 78.4% | 8.1 min | 1.4% |
Carriers with at least 24 flights in the 12 months to July 2026. The on-time pill is green when a carrier is at or above the route's overall share. Regional carriers operate flights sold under larger airlines' brands; BTS lists the carrier that operated the flight.
Compared with the airports and the nation
| Measure | ONT to ORD | All departures from ONT | All arrivals at ORD | All reported flights |
|---|---|---|---|---|
| Arrived on time | 78.4% | 81.2% | 71.2% | 76.0% |
| Arrived 15+ minutes late | 18.9% | 17.7% | 25.4% | 21.9% |
| Cancelled | 1.4% | 0.9% | 2.9% | 1.8% |
| Diverted | 1.4% | 0.2% | 0.5% | 0.3% |
| Average arrival delay | 8.1 min | 4.0 min | 15.4 min | 8.1 min |
| Delay minutes per 100 flights | 1,553 | 1,296 | 2,373 | 1,684 |
| Scheduled flights | 291 | 25,854 | 359,867 | 7,043,858 |
12 months to July 2026. Delay minutes count late arrivals only (an early arrival is zero), so the per-100-flights row is a normalised total rather than an average of early and late.
The return direction, ORD to ONT, recorded 60.3% on time across 290 flights in the same period.
Month by month
By scheduled departure hour
Delay causes
Seasonality
| Calendar month | Flights | On time | Cancelled | Avg arrival delay | Years in sample |
|---|---|---|---|---|---|
| Jan | 5 | 100.0% | 0.0% | -14.0 min | 1 |
| Mar | 27 | 70.4% | 3.7% | 15.1 min | 1 |
| Apr | 30 | 80.0% | 3.3% | 9.4 min | 1 |
| May | 41 | 78.0% | 0.0% | 5.3 min | 2 |
| Jun | 60 | 83.3% | 0.0% | -0.9 min | 2 |
| Jul | 62 | 79.0% | 3.2% | 0.8 min | 2 |
| Aug | 31 | 80.6% | 0.0% | 3.5 min | 1 |
| Sep | 30 | 83.3% | 0.0% | 7.4 min | 1 |
| Oct | 31 | 71.0% | 0.0% | 2.1 min | 1 |
| Nov | 30 | 76.7% | 0.0% | 48.0 min | 1 |
| Dec | 15 | 80.0% | 0.0% | 6.5 min | 1 |
Each calendar month summed across the 36 months on file, so most rows combine three years. The pill compares the month with the route's own 12-month share.
Other routes from Ontario (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% |
All 25 routes and the airport record for ONT · airport record for ORD
Questions and answers
How often are flights from Ontario to Chicago on time?
78.4% of the 291 flights scheduled from ONT to ORD in the 12 months to July 2026 arrived less than 15 minutes after their scheduled time. The national share for the same period was 76.0%. Cancelled and diverted flights count as not on time.
Which airline has the highest on-time share from ONT to ORD?
United Airlines is the only reporting carrier with at least 60 flights on the route in the period, so there is no comparison to make.
What causes delays between Ontario and Chicago?
For flights that arrived 15 or more minutes late, carriers attributed the delay minutes as follows: air carrier 49%, national aviation system 37%, late-arriving aircraft 15%, extreme weather 0%, security 0%. The categories are the carriers' own reports to BTS; weather that slows the wider system is usually recorded under the National Aviation System rather than extreme weather.
What time of day has the highest on-time share from ONT?
Flights scheduled to leave ONT from 6 am to 7 am arrived on time 81.9% of the time, the highest of any hour with enough flights to compare. The lowest was 11 pm to 12 am at 76.7%. Delays tend to build through the day as late aircraft carry over to later flights.
Is it getting better?
The route does not have enough flights in the previous 12 months for a year-on-year comparison. The monthly chart on this page shows the months that are available.
Where does this data come from?
Every figure is computed from the Bureau of Transportation Statistics Reporting Carrier On-Time Performance files, which list each scheduled domestic flight by the carriers required to report. This page covers August 2023 to July 2026. It shows totals and averages only; it is not a live flight-status service.
Provenance
Source: Bureau of Transportation Statistics, Reporting Carrier On-Time Performance (1987 to present), monthly files August 2023 to July 2026, a US government work in the public domain. Figures are totals and averages over all scheduled flights by reporting carriers on the route; no individual flight or aircraft is identified. Times are local to the departure airport. The load factor and passenger counts from the BTS T-100 series are not included in this edition. See the methodology; report processing errors through corrections.