Route profile
ONT→MDW
Flight reliability, delays and best times to fly from Ontario to Chicago. · 1,706 miles
Right now
Current conditions at both ends of this route.
Aviation weather is not currently a factor.
Aviation weather is not currently a factor.
Airport conditions describe the airfield, not any individual flight. An airport operating normally is not a guarantee that a specific flight will depart on time.
Route reliability
July 2023 – June 2026
Better than 100% of comparable major US routes (4,577 compared)
Calculated from 1,084 flights. How this is calculated
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – June 2026
Best time to fly
On-time arrival rate by scheduled local departure time.
ONT → MDW flights departing 5–9 AM arrived on time 91.5% of the time, against 77.5% for 12–3 PM departures — a gap of 14.0 percentage points.
By departure window
By departure hour
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – June 2026 · Buckets with fewer than 120 flights are not scored.
Why ONT → MDW runs late
Where US DOT attributed the delay minutes on this route.
crew, maintenance, boarding, fuelling — within the carrier’s control
the inbound aircraft was late, so this flight started late
airspace and airport capacity, including weather-driven flow control
screening or terminal security incidents
Share of the delay minutes US DOT attributed to each cause for ONT → MDW. A single late flight can carry more than one cause, and only delays of fifteen minutes or more are attributed at all.
A route inherits the problems of both ends and of the aircraft flying it. A large share attributed to late-arriving aircraft usually means the departure sits late in a busy rotation rather than that anything about this city pair is difficult, which is why the same route often performs very differently at different times of day.
Airlines on this route
Performance by the carrier that actually operated the flight.
| Carrier | Flights | On time | Cancelled | Median delay | Severe |
|---|---|---|---|---|---|
| Southwest Airlines | 1,084 | 89.2% | 0.37% | -7 min | 2.2% |
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – June 2026 · Carriers with fewer than 200 flights on this route are not listed.
Other ways to fly Los Angeles to Chicago
Airport pairs serving the same journey, grouped by the DOT's own city-market definition. They do not perform the same way.
| Route | Flights | On time | Cancelled | Median delay | Score |
|---|---|---|---|---|---|
| LAX→ORD Los Angeles to Chicago | 20,418 | 81.1% | 1.26% | -9 min | 68 |
| SNA→ORD Santa Ana to Chicago | 6,534 | 81.2% | 0.64% | -8 min | 72 |
| LAX→MDW Los Angeles to Chicago | 4,131 | 80.5% | 0.56% | -5 min | 79 |
| ONT→MDW this route Ontario to Chicago | 1,084 | 89.2% | 0.37% | -7 min | 93 |
| BUR→MDW Burbank to Chicago | 904 | 88.4% | 0.33% | -9 min | 90 |
ONT → MDW is the most reliable pairing for this journey at 89.2% on time, against 81.1% for LAX → ORD.
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – June 2026 · Grouped by DOT city market, which places Newark with the New York airports and Baltimore with the Washington ones.
Weekly and seasonal patterns
By day of week
Friday is historically the most reliable day and Wednesday the least, a gap of 5.8 percentage points.
Historical trend
On-time arrival rate by month.
Over the most recent 12 months (2025-07 to 2026-06), on-time arrivals averaged 89.9% against 89.4% in the 12 months before — broadly unchanged.
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – June 2026
Data and methodology
All figures on this page are calculated by FlyerIntel from 1,084 ONT → MDW flight records published by the US DOT Bureau of Transportation Statistics, covering July 2023 – June 2026. A flight is counted as delayed when it arrives 15 or more minutes after its scheduled arrival time, following BTS methodology. Cancelled and diverted flights have no arrival time and are excluded from on-time rates rather than counted as late.
Full methodology · Data sources · Report a problem
Analysis last recomputed