Carrier route record
UASAN→ORD
United Airlines · San Diego to Chicago
- Flights
- 1,672
- Period
- July 2025 to June 2026
- Share of route
- 44%
- Carriers
- 4
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on SAN to ORD lands a B+, 4 points better than the national rate of 77.6%. About one flight in six arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 1,672 flights. The strongest carrier on the route with a full sample, American Airlines, flew 1,386 at 77.3% on time.
Set against the rest of the country, United's SAN to ORD record is 4 points better than the US average of 77.6%. That gap is worth roughly 44 fewer late arrivals for every thousand flights.
Key figures
On time
82.0%
Arrivals under 15 minutes late, of 1,647 completed flights
Avg delay
76 min
Across delayed arrivals only, not all flights
Cancelled
0.54%
National rate is 1.81%
Whole route
78.0%
Every carrier on SAN to ORD, 3,807 flights
These figures cover 1,672 flights between July 2025 and June 2026. The median arrival is 8 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
Carrier by carrier
United against every carrier on SAN to ORD
United flew 1,672 of the 3,807 flights on SAN to ORD, about 44% of it. Its 82.0% on time is 4 points better than the route as a whole, which runs 78.0%. Ranked by on-time rate it is first of four carriers on the route, where the range runs from United at 82.0% to Frontier at 38.3%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The two carriers here are closely matched: 4 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines (this page) | 1,672 | 82.0% | 76 min | 0.54% | B+ |
| American Airlines | 1,386 | 77.3% | 93 min | 1.80% | B |
| Alaska Airlines | 688 | 73.5% | 64 min | 2.33% | C |
| Frontier Airlinesthin sample | 61 | 38.3% | 111 min | 1.64% | F |
No carrier stands out. American tops the table at 77.3%, 4 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Flight by flight
United flight numbers on SAN to ORD
Departure window
When United runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 26 points, against 4 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am341 flights86.5%
- 8am–11am179 flights80.6%
- 11am–2pm185 flights82.0%
- 2pm–5pm473 flights69.8%
- 5pm–8pm210 flights84.5%
- 8pm–5am284 flights95.7%
Scale runs 60% to 100%. Rows with fewer than 30 flights show a dash.
The overnight block holds up unusually well at 95.7% on time across 284 flights. Red-eyes fly into empty airspace and empty gates, and they are the first rotation of the aircraft's day rather than the last. The 2pm–5pm window is the busiest, with 473 flights scheduled in it.
Across the year
United on SAN to ORD through the year
Delays peak in March, when the on-time rate falls to 74.8%. February is the strongest month at 87.8%. Moving a flexible trip across that boundary buys 13 points. October was the busiest month here, with 155 flights.
Across the week, Tuesday is the strongest day at 87.2% on time and Sunday the weakest at 75.1%. 12 points is a smaller lever than departure hour, but it is free.
Delay causes
Why United runs late on this route
One category carries most of the weight here. National Airspace System accounts for 43% of the 22,000 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 43%National Airspace System
- 33%Late-arriving aircraft
- 24%Carrier
43% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 9,668 minutes out of 22,000, against a national NAS share of 21%. The split is drawn from 22,442 reported delay minutes.
Cancellations are rare at 0.54%, below the national 1.81% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.
Connections and stage length
What a delay here costs
5.9% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last a little over an hour, which a normal layover absorbs.
At 1,723 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The return leg is a different operation and performs like one: it runs 77.0% on time across 1,672 flights, 5 points below this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 5 points of difference.
The sample behind these figures is 1,672 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
What to do with this
Booking United on SAN to ORD
Put together: the calendar is the biggest lever here, not the carrier or the hour. February runs 87.8% on time and March 74.8%, a swing of 13 points. If the dates move at all, move them out of March before you think about anything else. 1,647 completed flights over 12 months sit behind that.
Related
Where to go next
- SAN to ORD, every carrier
- United on ORD to SAN, the return leg
- American Airlines on SAN to ORD77.3%
- Alaska Airlines on SAN to ORD73.5%
- United Airlines network-wide record
- San Diego International (SAN) delay statistics
- Chicago O'Hare International (ORD) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.