Route reliability record
ORD→SJU
Chicago to San Juan
- Flights
- 1,403
- Period
- July 2025 to June 2026
- Distance
- 2,072 mi
- Carriers
- 4
This route sits in the middle of the pack with a C. Close to three flights in four arrive on time by the DOT's definition, 4 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 1,403 ORD to SJU flights, of which United Airlines flew 665 at 78.9% on time.
Best time to fly ORD to SJU: a 2pm–5pm departure, ideally on a Wednesday. Flights in that window arrived on time 79.6% of the time and Wednesday flights 78.0%, against 73.8% for the route overall.
The US average over the same twelve months is 77.6%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
73.8%
Arrivals under 15 minutes late, of 1,372 completed flights
Avg delay
59 min
Across delayed arrivals only, not all flights
Cancelled
2.00%
National rate is 1.81%
Best carrier
United
78.9% on time across 665 flights
These figures cover 1,403 flights between July 2025 and June 2026. Beyond the headline rate, 8.3% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Carrier by carrier
Which airline is most reliable on ORD to SJU
The choice of carrier is not cosmetic here. United Airlines arrives on time 78.9% of the time; American Airlines manages 72.9%. Sample sizes sit next to every figure, because a two-point gap across 429 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 665 | 78.9% | 45 min | 0.30% | B+ |
| Frontier Airlinesthin sample | 12 | 75.0% | 20 min | 0.00% | B+ |
| American Airlines | 429 | 72.9% | 64 min | 1.40% | C |
| Spirit Airlinesthin sample | 297 | 62.7% | 74 min | 6.73% | D− |
United leads American by 6 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Flight by flight
Flights on ORD to SJU
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.
Best ways to make this trip
The most reliable ways to fly Chicago to San Juan
Every airline on this route, ranked by how often a scheduled flight actually operated and arrived on time, with its best departure time and most punctual flight number. No nearby airport pair beat these.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. ORD → SJUChicago to San Juan | United Airlines | 78.7% | 78.9% | 0.30% | 8am–11am, Wed | UA 1996 08:55 |
| 2. ORD → SJUChicago to San Juan | American Airlines | 71.9% | 72.9% | 1.40% | 8pm–5am, Wed | — |
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 28 points, against 6 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am50 flights76.1%
- 8am–11am688 flights78.4%
- 11am–2pm142 flights65.0%
- 2pm–5pm287 flights79.6%
- 5pm–8pm120 flights51.3%
- 8pm–5am116 flights63.5%
Scale runs 45% to 85%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 51.3% on time, against 79.6% for the 2pm–5pm slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 8am–11am window is the busiest, with 688 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 28 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.
Delays peak in March, when the on-time rate falls to 59.4%. February is the strongest month at 87.1%. Moving a flexible trip across that boundary buys 28 points. March was the busiest month here, with 179 flights.
Across the week, Wednesday is the strongest day at 78.0% on time and Sunday the weakest at 68.0%. 10 points is a smaller lever than departure hour, but it is free.
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 21,000 reported delay minutes.
- 33%Carrier
- 32%National Airspace System
- 26%Late-arriving aircraft
- 9%Extreme weather
- 0%Security
No single cause dominates. carrier at 33%, national airspace system at 32% and late-arriving aircraft at 26% split the 21,000 reported delay minutes between them. An even spread like this usually means the operation is running close to its designed capacity with no one obvious weak point, and it is the hardest pattern for a traveller to route around. The split is drawn from 21,289 reported delay minutes.
Cancellations sit at 2.00% against a national 1.81%, which is ordinary. Diversions add another 0.21%.
Connections and stage length
What a delay here actually costs
8.3% 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 about an hour, which a normal layover absorbs.
At 2,072 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 79.5% on time across 1,397 flights, 6 points above 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 6 points of difference.
The sample behind these figures is 1,403 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 SJU 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 87.1% on time and March 59.4%, a swing of 28 points. If the dates move at all, move them out of March before you think about anything else. 1,372 completed flights over 12 months sit behind that.
Common questions
ORD to SJU questions
How often is ORD to SJU delayed?
About 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 26.2% of the 1,403 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on ORD to SJU?
United Airlines leads at 78.9% on time across 665 flights. American Airlines is at the other end on 72.9%, a gap of 6 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 ORD to SJU?
The 2pm–5pm departure window is the strongest at 79.6% on time. The 5pm–8pm window is the weakest at 51.3%, 28 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 March delays on ORD to SJU?
March is the weakest month at 59.4% on time, compared with 87.1% in February. Across the year that is 28 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
- SJU to ORD — the return legseparate record
- Chicago O'Hare International (ORD) delay statistics
- Luis Munoz Marin International (SJU) delay statistics
- United Airlines on ORD to SJU78.9%
- American Airlines on ORD to SJU72.9%
- Spirit Airlines on ORD to SJU62.7%
- ORD to LGA, a related route67.3%
- MCO to SJU, a related route73.0%
- ORD to BOS, a related route67.6%
- United Airlines on-time record78.9%
- Frontier Airlines on-time record75.0%
- American Airlines on-time record72.9%
- The best time of day to fly, according to 7.04 million flight records
- Connecting flights: how much buffer the data says you need
Direction matters. ORD to SJU and SJU to ORD 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.