Route profile
IAH→ONT
Flight reliability, delays and best times to fly from Houston to Ontario, 1,334 miles.
Right now
Aviation weather is not currently a factor.
Aviation weather is not currently a factor.
Route reliability
May 2024 – July 2026
Better than 11% of comparable major US routes (4,598 compared)
Calculated from 1,219 flights. How this is calculated · What counts as on time
IAH → ONT arrives on time 68.5% of the time; the return trip, ONT → IAH, arrives on time 81.7% of the time, a 13.2-point gap between the two directions of the same city pair.
IAH → ONT spends 27.0 minutes on the ground on a 1,334-mile trip: 21.4 minutes from pushback to wheels-up at IAH and 5.6 minutes from touchdown to gate at ONT.
Source: US DOT Bureau of Transportation Statistics · Data covering May 2024 – July 2026
What stands out
Reliability on this route has improved unusually sharply over the past year, a bigger swing than 98% of 5,368 comparable routes.
78.1% on time over the most recent 12 months (2025-08 to 2026-07), against 63.2% in the 12 months before (2024-08 to 2025-07), a change of 14.9 points.
Source: FlyerIntel analysis of US DOT BTS data · May 2024 – July 2026 · Ranked against every other route with the same kind of figure and at least 5,368 in the comparison.
What sets this route apart
Where IAH to ONT differs most from similar routes by hour, weekday, month and airline, May 2024 – July 2026.
IAH to ONT struggles most at 7 PM: 56.9% of its flights scheduled then arrive on time, 10.1 points behind the 67.0% on routes of similar length at the same hour. Against all other routes the gap is 10.9 points.
IAH to ONT is at its best against routes of similar length for flights scheduled at 8 PM: 73.1% arrive on time, 7.9 points ahead of the 65.2% those routes manage at that hour. Against all other routes the gap is 5.7 points.
Monday is the day IAH to ONT slips furthest against routes of similar length, 61.5% on time where they average 77.0%, 15.5 points lower. Against all other routes the gap is 15.8 points.
In June, IAH to ONT runs 17.4 points below routes of similar length, 54.5% on time to 71.9%. Against all other routes the gap is 18.2 points.
United Airlines’ flights on IAH to ONT arrive on time 71.7% of the time, 9.5 points below the 81.2% it manages on its routes of similar length. Against all other routes the gap is 8.2 points.
IAH to ONT against comparable routes
May 2024 – July 2026| Measure | This route | Compared with | Them | Gap | Flights behind it |
|---|---|---|---|---|---|
| Hour: 7 PM departures | 56.9% | routes of similar length | 67.0% | −10.1 pts | 181 here, 84,523 there |
| Hour: 8 PM departures | 73.1% | routes of similar length | 65.2% | +7.9 pts | 673 here, 61,144 there |
| Weekday: Monday | 61.5% | routes of similar length | 77.0% | −15.5 pts | 218 here, 249,781 there |
| Month: June | 54.5% | routes of similar length | 71.9% | −17.4 pts | 145 here, 138,689 there |
| Airline: United Airlines | 71.7% | routes of similar length | 81.2% | −9.5 pts | 796 here, 303,500 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 1,334 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
May 2024 – July 2026
67 min late
against a median of 0 min early
IAH → ONT has an average that understates its risk: a typical arrival is 0 min early, but the worst tenth are 67 minutes worse than that. If the trip has something unmissable at the end of it, the median is the wrong number to plan against.
Percentiles over 1,219 operations; cancelled and diverted flights are counted separately.
Will your connection be tight enough?
Layovers at ONT after arriving from IAH.
| Connection time | Chance of missing | Reads as |
|---|---|---|
| 30 min | 49% | Likely to miss |
| 45 min | 30% | Likely to miss |
| 60 min | 20% | High risk |
| 90 min | 12% | Some risk |
| 120 min | 7.0% | Some 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 1.07% of the time and diverts 0.16% of the time, which a late arrival never shows up in.
Chance of missing is the share of 1,204 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 67 minutes late (90th-percentile gate arrival delay), over 1,219 operations.
Any other layover length: connection checker.
Why IAH → ONT runs late
May 2024 – 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
Share of the delay minutes US DOT attributed to each cause for IAH → ONT. Only delays of 15 minutes or more are attributed. What the five causes mean
Late-arriving aircraft is the largest cause on IAH → ONT, at 51.9%: flights here mostly leave late because the plane came in late.
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 |
|---|---|---|---|---|---|
| United Airlines | 802 | 71.7% | 0.50% | -1 min | 12.2% |
| Frontier Airlines | 417 | 62.3% | 2.16% | 2 min | 11.3% |
United Airlines flew 65.8% of the 1,219 flights listed. Frontier Airlines cancelled 2.16% of its flights here against 0.50% for United Airlines.
United Airlines arrived on time 9.4 percentage points more often than Frontier Airlines on this route.
Other ways to fly Houston to Los Angeles
Airport pairs in the same two city markets, as the DOT defines them.
| Route | Flights | On time | Cancelled | Median delay | Score |
|---|---|---|---|---|---|
| IAH→LAX Houston to Los Angeles | 16,491 | 82.8% | 1.01% | -8 min | 74 |
| IAH→ONT this route Houston to Ontario | 1,219 | 68.5% | 1.07% | 0 min | 47 |
IAH → LAX is the most reliable pairing for this journey at 82.8% on time, against 68.5% for IAH → ONT.
Flying to ONT from the Houston area? Compare IAH, HOU for ONT, with the same test for what counts as a real difference.
Weekly and seasonal patterns
By day of week
Tuesday is historically the most reliable day and Monday the least, a gap of 14.4 percentage points.
Reliability over time
May 2024 – July 2026
Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 78.1% against 63.2% in the 12 months before — improving by 14.9 percentage points.
Data and methodology
Calculated by FlyerIntel from 1,219 IAH → ONT flight records from the US DOT Bureau of Transportation Statistics, covering May 2024 – 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