Route profile
ONT→IAH
Flight reliability, delays and best times to fly from Ontario to Houston, 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 61% of comparable major US routes (4,598 compared)
Calculated from 1,216 flights. How this is calculated · What counts as on time
ONT → IAH arrives on time 81.7% of the time; the return trip, IAH → ONT, arrives on time 68.5% of the time, a 13.2-point gap between the two directions of the same city pair.
ONT → IAH spends 27.5 minutes on the ground on a 1,334-mile trip: 15.7 minutes from pushback to wheels-up at ONT and 11.8 minutes from touchdown to gate at IAH.
Source: US DOT Bureau of Transportation Statistics · Data covering May 2024 – July 2026
What stands out
Which day you fly matters unusually much here, a wider weekday spread than 97% of 4,467 comparable routes.
91.0% on time on a typical Tuesday, against 74.3% on a Monday.
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 4,467 in the comparison.
What sets this route apart
Where ONT to IAH differs most from similar routes by hour, weekday, month and airline, May 2024 – July 2026.
ONT to IAH struggles most at 6 AM: 88.5% of its flights scheduled then arrive on time, 2.3 points behind the 90.8% on routes of similar length at the same hour. Against all other routes the gap is 2.3 points.
ONT to IAH holds up on Tuesdays better than routes of similar length do: 91.0% on time to their 80.9%, a 10.1 points lead. Against all other routes the gap is 9.4 points.
May is kinder to ONT to IAH than to routes of similar length: 83.6% on time against 74.0%, 9.6 points better. Against all other routes the gap is 8.4 points.
United Airlines does better on ONT to IAH than on its routes of similar length: 88.8% on time here, 81.2% there, 7.6 points apart. Against all other routes the gap is 8.9 points.
ONT to IAH against comparable routes
May 2024 – July 2026| Measure | This route | Compared with | Them | Gap | Flights behind it |
|---|---|---|---|---|---|
| Hour: 6 AM departures | 88.5% | routes of similar length | 90.8% | −2.3 pts | 704 here, 127,225 there |
| Weekday: Tuesday | 91.0% | routes of similar length | 80.9% | +10.1 pts | 133 here, 231,419 there |
| Month: May | 83.6% | routes of similar length | 74.0% | +9.6 pts | 122 here, 140,096 there |
| Airline: United Airlines | 88.8% | routes of similar length | 81.2% | +7.6 pts | 792 here, 303,504 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
34 min late
against a median of 3 min early
Percentiles over 1,216 operations; cancelled and diverted flights are counted separately.
Will your connection be tight enough?
Layovers at IAH after arriving from ONT.
| Connection time | Chance of missing | Reads as |
|---|---|---|
| 30 min | 39% | Likely to miss |
| 45 min | 18% | High risk |
| 60 min | 11% | Some risk |
| 90 min | 6.0% | Some risk |
| 120 min | 3.6% | 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 1.32% of the time and diverts 0.08% of the time, which a late arrival never shows up in.
Chance of missing is the share of 1,199 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 34 minutes late (90th-percentile gate arrival delay), over 1,216 operations.
Any other layover length: connection checker.
Best time to fly
ONT → IAH flights departing 5–9 AM arrived on time 88.3% of the time, against 60.0% for 3–6 PM departures, a gap of 28.3 percentage points.
By departure window
By departure hour
- 12 AM to 5 AM: too few flights to score
- 6 AM: 88.5% on time from 711 flights
- 7 AM to 11 PM: too few flights to score
Departure windows with fewer than 120 flights are not scored.
Why ONT → IAH 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 ONT → IAH. Only delays of 15 minutes or more are attributed. What the five causes mean
Late-arriving aircraft is the largest cause on ONT → IAH, at 38.4%: flights here mostly leave late because the plane came in late, and the day shows it: 5–9 AM departures arrived on time 88.3% of the time and 3–6 PM departures 60.0%.
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 | 800 | 88.8% | 0.88% | -4 min | 3.5% |
| Frontier Airlines | 416 | 68.1% | 2.16% | 0 min | 10.8% |
United Airlines flew 65.8% of the 1,216 flights listed. Frontier Airlines cancelled 2.16% of its flights here against 0.88% for United Airlines.
United Airlines arrived on time 20.7 percentage points more often than Frontier Airlines on this route.
Other ways to fly Los Angeles to Houston
Airport pairs in the same two city markets, as the DOT defines them.
| Route | Flights | On time | Cancelled | Median delay | Score |
|---|---|---|---|---|---|
| LAX→IAH Los Angeles to Houston | 16,477 | 85.3% | 1.03% | -9 min | 78 |
| ONT→IAH this route Ontario to Houston | 1,216 | 81.7% | 1.32% | -3 min | 69 |
LAX → IAH is the most reliable pairing for this journey at 85.3% on time, against 81.7% for ONT → IAH.
Flying to IAH from the Los Angeles area? Compare ONT, LAX, SNA, BUR for IAH, 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 16.7 percentage points.
Reliability over time
May 2024 – July 2026
Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 85.2% against 81.9% in the 12 months before — improving by 3.3 percentage points.
Data and methodology
Calculated by FlyerIntel from 1,216 ONT → IAH 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