Route profile
OAK→ONT
Flight reliability, delays and best times to fly from Oakland to Ontario, 362 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 93% of comparable major US routes (4,598 compared)
Calculated from 4,804 flights. How this is calculated
OAK → ONT arrives on time 84.5% of the time; the return trip, ONT → OAK, arrives on time 87.1% of the time, a 2.6-point gap between the two directions of the same city pair.
OAK → ONT spends 16.5 minutes on the ground on a 362-mile trip: 12.0 minutes from pushback to wheels-up at OAK and 4.5 minutes from touchdown to gate at ONT.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
What stands out
This route holds up about the same all year, a steadier seasonal pattern than 92% of 3,357 comparable routes.
90.9% on time in its best month (January) against 80.2% in its worst (May).
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 3,357 in the comparison.
What sets this route apart
Where OAK to ONT differs most from similar routes by hour, weekday, month and airline, July 2023 – July 2026.
OAK to ONT is at its best against routes of similar length for flights scheduled at 6 PM: 86.0% arrive on time, 16.3 points ahead of the 69.7% those routes manage at that hour. Against all other routes the gap is 17.5 points.
OAK to ONT struggles most at 7 PM: 63.2% of its flights scheduled then arrive on time, 6.8 points behind the 70.0% on routes of similar length at the same hour.
OAK to ONT holds up on Saturdays better than routes of similar length do: 89.7% on time to their 81.5%, a 8.2 points lead. Against all other routes the gap is 10.6 points.
July is kinder to OAK to ONT than to routes of similar length: 81.4% on time against 71.6%, 9.8 points better. Against all other routes the gap is 11.7 points.
Southwest Airlines does better on OAK to ONT than on its routes of similar length: 84.5% on time here, 80.1% there, 4.4 points apart. Against all other routes the gap is 7.1 points.
OAK to ONT against comparable routes
July 2023 – July 2026| Measure | This route | Compared with | Them | Gap | Flights behind it |
|---|---|---|---|---|---|
| Hour: 6 PM departures | 86.0% | routes of similar length | 69.7% | +16.3 pts | 393 here, 94,696 there |
| Hour: 7 PM departures | 63.2% | routes of similar length | 70.0% | −6.8 pts | 228 here, 89,925 there |
| Weekday: Saturday | 89.7% | routes of similar length | 81.5% | +8.2 pts | 496 here, 177,278 there |
| Month: July | 81.4% | routes of similar length | 71.6% | +9.8 pts | 516 here, 164,791 there |
| Airline: Southwest Airlines | 84.5% | routes of similar length | 80.1% | +4.4 pts | 4,780 here, 503,290 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 362 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
27 min late
against a median of 8 min early
Percentiles over 4,804 operations; cancelled and diverted flights are counted separately.
Will your connection be tight enough?
Layovers at ONT after arriving from OAK.
| Connection time | Chance of missing | Reads as |
|---|---|---|
| 30 min | 29% | High risk |
| 45 min | 15% | Some risk |
| 60 min | 9.1% | Some risk |
| 90 min | 3.9% | Low risk |
| 120 min | 2.1% | 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 0.48% of the time and diverts 0.02% of the time, which a late arrival never shows up in.
Chance of missing is the share of 4,780 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 27 minutes late (90th-percentile gate arrival delay), over 4,804 operations.
Any other layover length: connection checker.
Best time to fly
OAK → ONT flights departing 5–9 AM arrived on time 96.9% of the time, against 72.2% for 9 PM–5 AM departures, a gap of 24.7 percentage points.
By departure window
By departure hour
- 12 AM to 5 AM: too few flights to score
- 6 AM: 97.1% on time from 795 flights
- 7 AM: 97.7% on time from 175 flights
- 8 AM: 94.5% on time from 165 flights
- 9 AM: 92.7% on time from 250 flights
- 10 AM: 92.7% on time from 345 flights
- 11 AM: 88.8% on time from 313 flights
- 12 PM: 82.8% on time from 228 flights
- 1 PM: 86.8% on time from 296 flights
- 2 PM: 79.0% on time from 126 flights
- 3 PM: 81.2% on time from 261 flights
- 4 PM: 74.1% on time from 206 flights
- 5 PM: 77.3% on time from 355 flights
- 6 PM: 86.0% on time from 395 flights
- 7 PM: 63.2% on time from 229 flights
- 8 PM: 66.3% on time from 478 flights
- 9 PM: 74.4% on time from 133 flights
- 10 PM to 11 PM: too few flights to score
Why OAK → 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
Share of the delay minutes US DOT attributed to each cause for OAK → ONT. Only delays of 15 minutes or more are attributed.
Late-arriving aircraft is the largest cause on OAK → ONT, at 59.4%: flights here mostly leave late because the plane came in late, and the day shows it: 5–9 AM departures arrived on time 96.9% of the time and 9 PM–5 AM departures 72.2%.
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 | 4,804 | 84.5% | 0.48% | -8 min | 4.0% |
Other ways to fly San Francisco to Los Angeles
Airport pairs in the same two city markets, as the DOT defines them.
| Route | Flights | On time | Cancelled | Median delay | Score |
|---|---|---|---|---|---|
| SFO→LAX San Francisco to Los Angeles | 34,804 | 77.1% | 0.70% | -5 min | 67 |
| SJC→LAX San Jose to Los Angeles | 15,614 | 86.7% | 0.37% | -10 min | 88 |
| SFO→SNA San Francisco to Santa Ana | 13,715 | 80.2% | 1.13% | -6 min | 72 |
| OAK→ONT this route Oakland to Ontario | 4,804 | 84.5% | 0.48% | -8 min | 84 |
SJC → LAX is the most reliable pairing for this journey at 86.7% on time, against 77.1% for SFO → LAX.
Flying to ONT from the San Francisco area? Compare OAK, SFO, SJC for ONT, with the same test for what counts as a real difference.
Weekly and seasonal patterns
By day of week
Saturday is historically the most reliable day and Friday the least, a gap of 10.6 percentage points.
By month
- Jan: 90.9%
- Feb: 88.0%
- Mar: 83.6%
- Apr: 82.1%
- May: 80.2%
- Jun: 81.4%
- Jul: 81.4%
- Aug: 86.3%
- Sep: 84.5%
- Oct: 85.1%
- Nov: 89.2%
- Dec: 83.0%
May is historically the weakest month and January the strongest, a spread of 10.7 percentage points.
Reliability over time
July 2023 – July 2026
- July 2023: 80.6% from 134 flights
- August 2023: 83.3% from 143 flights
- September 2023: 76.9% from 143 flights
- October 2023: 82.6% from 144 flights
- November 2023: 91.0% from 144 flights
- December 2023: 86.2% from 152 flights
- January 2024: 86.6% from 127 flights
- February 2024: too few flights to score (112)
- March 2024: 84.5% from 130 flights
- April 2024: 85.9% from 129 flights
- May 2024: 76.5% from 132 flights
- June 2024: 84.6% from 131 flights
- July 2024: 81.8% from 133 flights
- August 2024: 88.3% from 137 flights
- September 2024: 90.1% from 132 flights
- October 2024: 91.1% from 135 flights
- November 2024: 92.2% from 130 flights
- December 2024: 84.1% from 126 flights
- January 2025: 92.4% from 120 flights
- February 2025: too few flights to score (116)
- March 2025: 87.5% from 136 flights
- April 2025: 84.8% from 132 flights
- May 2025: 88.2% from 146 flights
- June 2025: 84.4% from 135 flights
- July 2025: 85.8% from 134 flights
- August 2025: 87.4% from 135 flights
- September 2025: 87.2% from 133 flights
- October 2025: 81.6% from 136 flights
- November 2025: 84.0% from 130 flights
- December 2025: 77.7% from 121 flights
- January 2026: 94.1% from 120 flights
- February 2026: too few flights to score (115)
- March 2026: 78.3% from 121 flights
- April 2026: too few flights to score (115)
- May 2026: too few flights to score (117)
- June 2026: too few flights to score (112)
- July 2026: too few flights to score (116)
Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 81.8% against 88.5% in the 12 months before — declining by 6.7 percentage points.
Data and methodology
Calculated by FlyerIntel from 4,804 OAK → 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