ORD to ONT flight delays & on-time performance
Nonstop flights from Chicago O'Hare International Airport to Ontario International Airport · 1,700 miles · Aug 2025 – Jul 2026
No FAA-reported ground stops or delays at ORD or ONT right now. Individual flights can still be delayed by the airline; check with your airline for your flight.
Key facts
- Flights from Chicago (ORD) to Ontario (ONT) arrived on time 61% of the time in Aug 2025 – Jul 2026, worse than the 78% national average.
- 1.4% were cancelled, and 16% arrived an hour or more late.
- United Airlines is the only airline reporting nonstop flights on this route.
- Departures scheduled around 7pm did best (60% on time); around 8pm did worst (59%).
- Wednesday was the most reliable day to fly (68% on time) and Tuesday the least (55%).
- The largest source of delay minutes was late-arriving aircraft (54%).
Which airline is most on time from ORD to ONT?
Ranked by on-time arrival rate. Regional airlines fly under their partner's brand (e.g. SkyWest for Delta Connection or United Express).
| Airline | On time | Cancelled | Avg delay | 1 hr+ late | Flights |
|---|---|---|---|---|---|
| United Airlines | 61% | 1.4% | 31 min | 16.4% | 290 |
Best time of day to fly
On-time arrival rate by scheduled departure hour (local time).
- 7pm60%150 flights
- 8pm59%123 flights
Best day of the week
On-time arrival rate by day of departure.
- Monday58%2.4% cancelled
- Tuesday55%0.0% cancelled
- Wednesday68%0.0% cancelled
- Thursday66%2.4% cancelled
- Friday56%4.7% cancelled
- Saturday67%0.0% cancelled
- Sunday60%0.0% cancelled
On-time trend by month
Why flights are late
Share of delay minutes by cause, as reported by airlines to the DOT.
- Late-arriving aircraft54%
- Airline (crew, maintenance, cleaning, fueling)26%
- Air traffic control & airport congestion14%
- Extreme weather5%
- Security0%
Why flights are cancelled
Share of cancellations by reason.
- Extreme weather100%
- Airline (crew, maintenance, cleaning, fueling)0%
- Air traffic control & airport congestion0%
- Security0%
ORD to ONT: common questions
- How often are ORD to ONT flights on time?
- 61% of flights arrived less than 15 minutes late in Aug 2025 – Jul 2026, compared with 78% for all US flights.
- How often are flights from Chicago to Ontario cancelled?
- 1.4% of scheduled flights were cancelled (4 of 290).
- How long are typical delays?
- Across all flights the average arrival delay was 31 min (early arrivals count as zero). Flights that were late arrived 78 min behind schedule on average, and 16.4% of flights were an hour or more late.
- How long is taxi time at ORD?
- Flights on this route spent 32 min taxiing from the gate to takeoff on average.
Related routes
Return trip: ONT to ORD — 81% on time
More flights from Chicago
Data: U.S. DOT Bureau of Transportation Statistics, Aug 2025 – Jul 2026 (12 months). Latest month published by BTS: July 2026. Route: ORD → ONT, nonstop flights by US airlines that report to the DOT. How we calculate this.