Route profile
MDW→ONT
Flight reliability, delays and best times to fly from Chicago to Ontario, 1,706 miles.
Right now
Aviation weather is not currently a factor.
Aviation weather is not currently a factor.
Route reliability
July 2023 – July 2026
Better than 56% of comparable major US routes (4,598 compared)
Calculated from 1,116 flights. How this is calculated · What counts as on time
MDW → ONT arrives on time 76.9% of the time; the return trip, ONT → MDW, arrives on time 89.1% of the time, a 12.3-point gap between the two directions of the same city pair.
MDW → ONT spends 19.7 minutes on the ground on a 1,706-mile trip: 14.6 minutes from pushback to wheels-up at MDW and 5.0 minutes from touchdown to gate at ONT.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
What stands out
Which day you fly matters unusually much here, a wider weekday spread than 95% of 4,467 comparable routes.
81.9% on time on a typical Thursday, against 66.5% on a Sunday.
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026 · Ranked against every other route with the same kind of figure and at least 4,467 in the comparison.
What sets this route apart
Where MDW to ONT differs most from similar routes by hour, weekday, month and airline, July 2023 – July 2026.
MDW to ONT struggles most at 11 AM: 71.5% of its flights scheduled then arrive on time, 6.6 points behind the 78.1% on routes of similar length at the same hour. Against all other routes the gap is 9.5 points.
Sunday is the day MDW to ONT slips furthest against routes of similar length, 66.5% on time where they average 75.3%, 8.8 points lower. Against all other routes the gap is 8.3 points.
MDW to ONT against comparable routes
July 2023 – July 2026| Measure | This route | Compared with | Them | Gap | Flights behind it |
|---|---|---|---|---|---|
| Hour: 11 AM departures | 71.5% | routes of similar length | 78.1% | −6.6 pts | 179 here, 82,637 there |
| Weekday: Sunday | 66.5% | routes of similar length | 75.3% | −8.8 pts | 161 here, 202,387 there |
Each comparison pools the flights of other routes, with this route’s own left out. Similar length means within 15% of this route’s 1,706 miles, with at least 5 such routes. A bucket is set against the most comparable group that has enough flights: similar length, then the same origin (at least 3 routes), then all other routes. Hours, weekdays and months appear only where both sides have 120 completed flights, and airlines where both have 600. The gap must be at least 2 points and 2 standard errors, and only the largest gap each way is kept per measure. These are differences in the flights counted, not causes.
When it goes wrong
July 2023 – July 2026
39 min late
against a median of 2 min early
Percentiles over 1,116 operations; cancelled and diverted flights are counted separately.
Will your connection be tight enough?
Layovers at ONT after arriving from MDW.
| Connection time | Chance of missing | Reads as |
|---|---|---|
| 30 min | 45% | Likely to miss |
| 45 min | 22% | High risk |
| 60 min | 13% | Some risk |
| 90 min | 5.9% | Some risk |
| 120 min | 3.1% | Low risk |
This is one leg of a connection. Gate changes and the next flight's own schedule matter too. And a connection can fail before delay is even the question — this route cancels 0.99% of the time and diverts 0.27% of the time, which a late arrival never shows up in.
Chance of missing is the share of 1,102 arrivals on this route that landed later than the connection time less 30 minutes to reach the next gate.
The worst tenth of arrivals on this route land at least 39 minutes late (90th-percentile gate arrival delay), over 1,116 operations.
Any other layover length: connection checker.
Best time to fly
MDW → ONT flights departing 5–9 AM arrived on time 87.4% of the time, against 66.2% for 3–6 PM departures, a gap of 21.2 percentage points.
By departure window
By departure hour
- 12 AM to 7 AM: too few flights to score
- 8 AM: 88.3% on time from 137 flights
- 9 AM: too few flights to score
- 10 AM: 84.5% on time from 166 flights
- 11 AM: 71.5% on time from 181 flights
- 12 PM to 11 PM: too few flights to score
Departure windows with fewer than 120 flights are not scored.
Why MDW → ONT runs late
July 2023 – July 2026
the inbound aircraft was late, so this flight started late
crew, maintenance, boarding and fueling, all within the carrier’s control
airspace and airport capacity, including weather-driven flow control
weather severe enough to stop this flight specifically
screening or terminal security incidents
Share of the delay minutes US DOT attributed to each cause for MDW → ONT. Only delays of 15 minutes or more are attributed. What the five causes mean
Late-arriving aircraft is the largest cause on MDW → ONT, at 40.9%: flights here mostly leave late because the plane came in late, and the day shows it: 5–9 AM departures arrived on time 87.4% of the time and 3–6 PM departures 66.2%.
Airlines on this route
Carriers with at least 200 flights, by the airline that operated each one.
| Carrier | Flights | On time | Cancelled | Median delay | Severe |
|---|---|---|---|---|---|
| Southwest Airlines | 1,116 | 76.9% | 0.99% | -2 min | 6.0% |
Other ways to fly Chicago to Los Angeles
Airport pairs in the same two city markets, as the DOT defines them.
| Route | Flights | On time | Cancelled | Median delay | Score |
|---|---|---|---|---|---|
| ORD→LAX Chicago to Los Angeles | 21,173 | 76.4% | 1.19% | -6 min | 61 |
| MDW→ONT this route Chicago to Ontario | 1,116 | 76.9% | 0.99% | -2 min | 68 |
MDW → ONT is the most reliable pairing for this journey at 76.9% on time, against 76.4% for ORD → LAX.
Flying to ONT from the Chicago area? Compare MDW, ORD for ONT, with the same test for what counts as a real difference.
Weekly and seasonal patterns
By day of week
Thursday is historically the most reliable day and Sunday the least, a gap of 15.4 percentage points.
Reliability over time
July 2023 – July 2026
Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 70.4% against 81.5% in the 12 months before — declining by 11.1 percentage points.
Data and methodology
Calculated by FlyerIntel from 1,116 MDW → ONT flight records from the US DOT Bureau of Transportation Statistics, covering July 2023 – July 2026. Late means 15 or more minutes past scheduled arrival; cancelled and diverted flights are left out of on-time rates.
Full methodology · Data sources · Report a problem
Related research: How Long a Layover Needs to Be · Two Airlines on One Route · Best Time of Day to Fly From Major US Airports
Analysis last recomputed