Route reliability record
SAN→ORD
San Diego to Chicago
- Flights
- 3,944
- Period
- September 2025 to August 2026
- Distance
- 1,723 mi
- Carriers
- 4
This route lands a B, level with the national rate of 77.3%. Roughly one flight in four arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That rests on 3,944 SAN to ORD flights, of which United Airlines flew 1,677 at 80.0% on time.
Best time to fly SAN to ORD: a 8pm–5am departure, ideally on a Tuesday. Flights in that window arrived on time 92.7% of the time and Tuesday flights 83.6%, against 77.6% for the route overall.
United Airlines is the most reliable of the three carriers covered here at 80.0% on time across 1,677 flights.
Key figures
On time
77.6%
Arrivals under 15 minutes late, of 3,840 completed flights
Avg delay
79 min
Across delayed arrivals only, not all flights
Cancelled
1.34%
National rate is 1.89%
Best carrier
United
80.0% on time across 1,677 flights
These figures cover 3,944 flights between September 2025 and August 2026. Beyond the headline rate, 8.1% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
Which airline is most reliable on SAN to ORD
The choice of carrier is not cosmetic here. United Airlines arrives on time 80.0% of the time; Alaska Airlines manages 69.7%. Sample sizes sit next to every figure, because a two-point gap across 862 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 1,677 | 80.0% | 78 min | 0.54% | B+ |
| American Airlines | 1,400 | 79.5% | 98 min | 1.57% | B |
| Alaska Airlines | 862 | 69.7% | 61 min | 2.55% | C |
| Frontier Airlinesthin sample | 5 | 60.0% | 50 min | 0.00% | D+ |
United leads Alaska by 10 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Flight by flight
Flights on SAN to ORD
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
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Best ways to make this trip
The most reliable ways to fly San Diego to Chicago
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 1 of the top 4 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. SAN → ORDSan Diego to Chicago | United Airlines | 79.6% | 80.0% | 0.54% | 8pm–5am, Tue | UA 2486 16:41 |
| 2. SAN → ORDSan Diego to Chicago | American Airlines | 78.3% | 79.5% | 1.57% | 8pm–5am, Tue | — |
| 3. SAN → MDWSan Diego to Chicago | Southwest Airlines | 75.9% | 76.7% | 1.08% | 8pm–5am, Wed | — |
| 4. SAN → ORDSan Diego to Chicago | Alaska Airlines | 67.9% | 69.7% | 2.55% | 8am–11am, Tue | AS 1493 17:23 |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 26 points, against 10 points between the best and worst carrier.
- 5am–8am941 flights86.0%
- 8am–11am513 flights77.6%
- 11am–2pm792 flights69.3%
- 2pm–5pm769 flights66.8%
- 5pm–8pm433 flights75.7%
- 8pm–5am496 flights92.7%
Scale runs 60% to 100%.
The overnight block holds up unusually well at 92.7% on time across 496 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 5am–8am window is the busiest, with 941 flights scheduled in it.
Explore
Filter SAN to ORD by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On SAN to ORD, the best departure window is 8pm–5am at 92.7% on time and the worst is 2pm–5pm at 66.8%, a wide gap of 25.9 points. All US flights leaving 8pm–5am ran 70.1%.
- 5–8am86.0%
- 8–11am77.6%
- 11am–2pm69.3%
- 2–5pm66.8%
- 5–8pm75.7%
- 8pm–5am92.7%
best all US flightsScale 60% to 95%.
Across the year
When delays peak on this route
This route's year swings by 19 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
August is the worst month at 67.4% on time, 19 points below February, the best at 85.9%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. July was the busiest month here, with 398 flights.
Across the week, Tuesday is the strongest day at 83.6% on time and Sunday the weakest at 73.4%, a spread of 10 points.
Delay causes
Why this route gets delayed
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 68,000 reported delay minutes.
- 35%National Airspace System
- 30%Late-arriving aircraft
- 29%Carrier
- 5%Extreme weather
35% 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 24,000 minutes out of 68,000, against a national NAS share of 21%. The split is drawn from 68,428 reported delay minutes.
Cancellations sit at 1.34% against a national 1.89%, which is ordinary. Diversions add another 1.29%.
Connections and stage length
What a delay here actually costs
8.1% of arrivals land an hour or more late, close to the national 8.3%, so 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 70.5% on time across 3,945 flights, 7 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 7 points of difference.
The sample behind these figures is 3,944 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.
Work out the risk of missing a connection in ORD after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. February runs 85.9% on time and August 67.4%, a swing of 19 points. If the dates move at all, move them out of August before you think about anything else. 3,840 completed flights over 12 months sit behind that.
Common questions
SAN to ORD questions
How often is SAN to ORD delayed?
Roughly one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 22.4% of the 3,944 flights in this analysis, against 22.7% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on SAN to ORD?
United Airlines leads at 80.0% on time across 1,677 flights. Alaska Airlines is at the other end on 69.7%, a gap of 10 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on SAN to ORD?
The 8pm–5am departure window is the strongest at 92.7% on time. The 2pm–5pm window is the weakest at 66.8%, 26 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are August delays on SAN to ORD?
August is the weakest month at 67.4% on time, compared with 85.9% in February. Across the year that is 19 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- ORD to SAN — the return legseparate record
- San Diego International (SAN) delay statistics
- Chicago O'Hare International (ORD) delay statistics
- United Airlines on SAN to ORD80.0%
- American Airlines on SAN to ORD79.5%
- Alaska Airlines on SAN to ORD69.7%
- SAN to SFO, a related route59.5%
- LGA to ORD, a related route66.7%
- SAN to DEN, a related route78.4%
- United Airlines on-time record80.0%
- American Airlines on-time record79.5%
- Alaska Airlines on-time record69.7%
- Same route, different airline: where the carrier you pick matters most
- The best time of day to fly, according to 7.05 million flight records
Direction matters. SAN to ORD and ORD to SAN are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.