76% of flights from San Diego to Chicago arrived on time over the past 12 months. That is worse than the typical U.S. route. The 10 p.m. departures ran on time 92% of the time; the noon ones 58%. Most reliable airline: United Airlines (79%). 10% of flights arrived more than an hour late or not at all.
How late?
The on-time rate treats a flight 20 minutes late the same as one 5 hours late. Here's the split for SAN → ORD: when a flight was late, it was under 45 minutes late 56% of the time. About 1 in 13 flights landed an hour or more late, and 1 in 50 three hours or more; 1.3% were cancelled outright.
- On time or early76%
- 15–30 min late8.3%
- 30–60 min late5.9%
- 1–2 hours late4.2%
- 2–3 hours late1.5%
- 3+ hours late2.0%
- Diverted1.3%
- Cancelled1.3%
Share of all 3,944 scheduled flights, past 12 months, by arrival time against schedule.
By airline
| Airline | Flights | On time | Cancelled | Typical arrival | 1h+ late | Avg when late | Operated by |
|---|---|---|---|---|---|---|---|
| United Airlines | 1,677 | 79% | 0.5% | −6 min | 6.6% | +78 min | United Airlines |
| American Airlines | 1,400 | 77% | 1.6% | −11 min | 7.7% | +98 min | American Airlines |
| Alaska Airlines | 862 | 67% | 2.5% | 0 min | 9.7% | +61 min | Alaska Airlines |
| Frontier Airlines | 5 | — | — | — | — | — | Frontier Airlines |
Airline = the name on the ticket. Regional flights (e.g. "Delta Connection") count under the ticketing airline, and the operator is listed.
Best time of day to fly
On-time rate by scheduled departure hour (local time at SAN). Delays build through the day as late planes knock on, so early flights usually do best.
By airline and hour
| Departs | United Airlines | American Airlines | Alaska Airlines |
|---|---|---|---|
| 6 a.m. | 83% | 87% | — |
| 7 a.m. | 85% | 80% | 77% |
| 8 a.m. | — | — | 73% |
| 10 a.m. | 79% | — | — |
| noon | — | — | 58% |
| 1 p.m. | — | 65% | — |
| 2 p.m. | 65% | — | — |
| 3 p.m. | — | 66% | — |
| 4 p.m. | 69% | — | — |
| 5 p.m. | 85% | — | 67% |
| 10 p.m. | 93% | 90% | — |
Last flight of the day
On SAN → ORD, each airline's last flight of the day was cancelled 1.5% of the time, against 1.3% for its earlier flights, about the same. It arrived 3+ hours late 1.6% of the time (earlier flights: 2.3%). It matters more than the numbers suggest. Miss an earlier flight and there's another one that evening; miss the last one and you're usually waiting until morning.
| Airline | Last departure | Last: cancelled | Last: 3h+ late | Earlier: cancelled | Next morning |
|---|---|---|---|---|---|
| American Airlines | 10:45 p.m. | 1.9% | 2.5% | 1.5% | first flight 6:15 a.m. |
| Alaska Airlines | 5:23 p.m. | 2.1% | 1.2% | 2.8% | first flight 7:00 a.m. |
| United Airlines | 10:25 p.m. | 0.5% | 1.1% | 0.5% | first flight 6:40 a.m. |
Last flight = the airline's last scheduled departure on this route that day, on days it flies the route at least twice; past 12 months. Times are typical scheduled times over the latest three months.
By month
Each calendar month pooled over 2023–2026. Best: September (88%). Worst: July (69%).
By day of week
| Day | Flights | On time | Cancelled |
|---|---|---|---|
| Monday | 595 | 72% | 2.0% |
| Tuesday | 544 | 82% | 0.7% |
| Wednesday | 540 | 78% | 1.3% |
| Thursday | 579 | 74% | 1.0% |
| Friday | 583 | 74% | 0.7% |
| Saturday | 514 | 80% | 1.8% |
| Sunday | 589 | 71% | 1.9% |
Why flights were late
Share of delay minutes on flights 15+ minutes late, as reported to BTS by the airlines.
Cancellations: weather 25 · airline 16 · air traffic/airport 12
Month by month
Flight numbers on this route
Regular flights with at least 120 scheduled trips in the past year. Sorted by departure time.
| Flight | Departs | Flights | On time | Cancelled | Typical arrival | Operated by |
|---|---|---|---|---|---|---|
| AA 518 | 6:15 a.m. | 209 | 89% | 0.0% | −17 min | American Airlines |
| AS 1446 | 7:00 a.m. | 166 | 69% | 1.8% | +2 min | Alaska Airlines |
| UA 1710 | 10:52 a.m. | 237 | 78% | 0.8% | −2 min | United Airlines |
| AS 1478 | 12:40 p.m. | 216 | 54% | 3.2% | +10 min | Alaska Airlines |
| UA 1779 | 2:11 p.m. | 364 | 65% | 0.0% | +5 min | United Airlines |
| UA 2486 | 4:41 p.m. | 319 | 77% | 0.6% | −14 min | United Airlines |
| AS 1493 | 5:23 p.m. | 257 | 65% | 2.3% | −5 min | Alaska Airlines |
| UA 1457 | 10:40 p.m. | 153 | 90% | 0.7% | −14 min | United Airlines |
Worst days in the past year
| Date | Flights | On time | Cancelled |
|---|---|---|---|
| Jul 27, 2026 | 13 | 0% | 1 |
| Jan 30, 2026 | 8 | 0% | 0 |
| Nov 29, 2025 | 10 | 10% | 5 |
| Mar 15, 2026 | 11 | 18% | 4 |
| Nov 9, 2025 | 11 | 18% | 1 |
Nearby airport alternatives
Other ways to make the same trip, using airports within 60 miles of San Diego or Chicago. None has been clearly more reliable than SAN → ORD.
| Route | Flights | On time | Cancelled |
|---|---|---|---|
| SAN → ORD (this route) | 3,944 | 76% | 1.3% |
| SAN → MDW San Diego to Chicago Midway | 1,110 | 75% | 1.1% |
Questions
How often are flights from SAN to ORD on time?
76% of 3,944 scheduled flights from San Diego, CA to Chicago, IL arrived within 15 minutes of schedule between September 2025 and August 2026. 1.3% were cancelled.
What is the best time of day to fly SAN to ORD?
Flights scheduled to leave at 10 p.m. were the most reliable (92% on time). The noon departures were the least (58%).
Which airline is most on time from SAN to ORD?
United Airlines: 79% of its 1,677 flights on the route arrived on time. American Airlines: 77%. Alaska Airlines: 67%.
What month has the most delays from SAN to ORD?
July (69% on time). The best month is September (88%), over 2023–2026.
Is the last flight of the day from SAN to ORD more likely to be cancelled?
Not much. Each airline's last SAN–ORD flight of the day was cancelled 1.5% of the time over the past year, against 1.3% for its earlier flights. If the last flight is cancelled, the next one is usually the following morning.
Related
- ORD → SAN (return)
- San Diego (SAN) delays by hour
- Flights into Chicago O'Hare (ORD)
- United Airlines on-time record
- American Airlines on-time record
- Alaska Airlines on-time record
- Frontier Airlines on-time record
- Connecting off this flight? Check the risk
Domestic flights by the airlines that report to the U.S. DOT, plus their regional partners. "On time" means arriving less than 15 minutes after schedule; cancelled and diverted flights count as not on time. Past performance is a guide, not a forecast. Method.