ONT to ORD flight delays & on-time performance
Nonstop flights from Ontario International Airport to Chicago O'Hare International Airport · 1,700 miles · Aug 2025 – Jul 2026
No FAA-reported ground stops or delays at ONT or ORD right now. Individual flights can still be delayed by the airline; check with your airline for your flight.
Key facts
- Flights from Ontario (ONT) to Chicago (ORD) arrived on time 81% of the time in Aug 2025 – Jul 2026, better than the 78% national average.
- 1.4% were cancelled, and 6% arrived an hour or more late.
- United Airlines is the only airline reporting nonstop flights on this route.
- Departures scheduled around 6am did best (87% on time); around 11pm did worst (79%).
- Wednesday was the most reliable day to fly (87% on time) and Sunday the least (67%).
- The largest source of delay minutes was airline (crew, maintenance, cleaning, fueling) (49%).
Which airline is most on time from ONT to ORD?
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 | 81% | 1.4% | 16 min | 5.7% | 291 |
Best time of day to fly
On-time arrival rate by scheduled departure hour (local time).
- 6am87%72 flights
- 7am79%176 flights
- 11pm79%43 flights
Best day of the week
On-time arrival rate by day of departure.
- Monday85%0.0% cancelled
- Tuesday79%2.5% cancelled
- Wednesday87%0.0% cancelled
- Thursday79%0.0% cancelled
- Friday83%4.7% cancelled
- Saturday85%2.4% cancelled
- Sunday67%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.
- Airline (crew, maintenance, cleaning, fueling)49%
- Air traffic control & airport congestion37%
- Late-arriving aircraft14%
- Extreme weather0%
- Security0%
Why flights are cancelled
Share of cancellations by reason.
- Extreme weather100%
- Airline (crew, maintenance, cleaning, fueling)0%
- Air traffic control & airport congestion0%
- Security0%
ONT to ORD: common questions
- How often are ONT to ORD flights on time?
- 81% 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 Ontario to Chicago cancelled?
- 1.4% of scheduled flights were cancelled (4 of 291).
- How long are typical delays?
- Across all flights the average arrival delay was 16 min (early arrivals count as zero). Flights that were late arrived 74 min behind schedule on average, and 5.7% of flights were an hour or more late.
- How long is taxi time at ONT?
- Flights on this route spent 17 min taxiing from the gate to takeoff on average.
Related routes
Return trip: ORD to ONT — 61% on time
More flights from Ontario
Data: U.S. DOT Bureau of Transportation Statistics, Aug 2025 – Jul 2026 (12 months). Latest month published by BTS: July 2026. Route: ONT → ORD, nonstop flights by US airlines that report to the DOT. How we calculate this.