Carrier route record
UASAN→SFO
United Airlines · San Diego to San Francisco
- Flights
- 2,666
- Period
- September 2025 to August 2026
- Share of route
- 39%
- Carriers
- 5
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with United Airlines.
United on SAN to SFO draws a C+. About one flight in three arrives at least 15 minutes late, and the typical late arrival is about an hour behind schedule. Build slack into anything you connect to. That rests on 2,666 flights. The strongest carrier on the route with a full sample, SkyWest Airlines, flew 1,482 at 59.8% on time.
The national on-time rate over the same period is 77.3%, so United on SAN to SFO runs 10 points behind the country as a whole. Across a thousand flights that is about 101 extra late arrivals.
Key figures
On time
67.2%
Arrivals under 15 minutes late, of 2,650 completed flights
Avg delay
57 min
Across delayed arrivals only, not all flights
Cancelled
0.56%
National rate is 1.89%
Whole route
59.5%
Every carrier on SAN to SFO, 6,763 flights
These figures cover 2,666 flights between September 2025 and August 2026. Beyond the headline rate, 10.0% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
United against every carrier on SAN to SFO
United flew 2,666 of the 6,763 flights on SAN to SFO, about 39% of it. Its 67.2% on time is 8 points better than the route as a whole, which runs 59.5%. Ranked by on-time rate it is first of five carriers on the route, where the range runs from United at 67.2% to Frontier at 37.9%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 59.8% of the time; Southwest Airlines manages 52.4%. Sample sizes sit next to every figure, because a two-point gap across 2,070 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines (this page) | 2,666 | 67.2% | 57 min | 0.56% | C+ |
| SkyWest Airlines | 1,482 | 59.8% | 64 min | 1.96% | D |
| Alaska Airlinesthin sample | 331 | 53.1% | 52 min | 1.51% | F |
| Southwest Airlines | 2,070 | 52.4% | 61 min | 1.30% | F |
| Frontier Airlinesthin sample | 214 | 37.9% | 75 min | 5.14% | F− |
SkyWest leads Southwest by 7 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Flight by flight
United flight numbers on SAN to SFO
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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 17 points, against 7 points between the best and worst carrier.
- 5am–8am565 flights75.8%
- 8am–11am415 flights66.3%
- 11am–2pm555 flights65.0%
- 2pm–5pm413 flights73.7%
- 5pm–8pm527 flights58.8%
- 8pm–5am191 flights59.6%
Scale runs 50% to 80%.
The 5pm–8pm window is where this operation falls apart: 58.8% on time, against 75.8% for the 5am–8am 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 5am–8am window is the busiest, with 565 flights scheduled in it.
Across the year
United on SAN to SFO through the year
Delays peak in May, when the on-time rate falls to 49.1%. March is the strongest month at 89.3%. Moving a flexible trip across that boundary buys 40 points. August was the busiest month here, with 257 flights.
Across the week, Saturday is the strongest day at 74.6% on time and Wednesday the weakest at 62.0%, a spread of 13 points.
Arrival by arrival
How late United on SAN to SFO runs when it is late
The 868 late arrivals split 308 under half an hour, 294 between 30 and 60 minutes, and 266 an hour or more.
- 15+ min early609 flights23.0%
- Within 15 min1,173 flights44.3%
- 15–29 min late308 flights11.6%
- 30–59 min late294 flights11.1%
- 1–2 hours late193 flights7.3%
- 2+ hours late73 flights2.8%
Scale runs 0% to 100%.
Share of 2,650 completed flights by arrival against schedule.
86 of 689 late departures made up the time and arrived on time, 12% of them. In the other direction, 265 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at SFO.
The worst days
Worst days for United on SAN to SFO
The latest arrival of the period was on 15 January 2026, 13 hours 18 minutes behind schedule; most of its delay minutes were filed as extreme weather. The five worst days are spread across January, September and July, with no single month standing out.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 15 January 2026 | 13 hours 18 minutes | Extreme weather |
| 17 September 2025 | 13 hours 16 minutes | National Airspace System |
| 5 January 2026 | 12 hours 53 minutes | Extreme weather |
| 6 July 2026 | 5 hours 24 minutes | Late-arriving aircraft |
| 18 July 2026 | 5 hours 24 minutes | Late-arriving aircraft |
Delay causes
Why United runs late on this route
National Airspace System accounts for 60% of the 49,000 delay minutes carriers reported here, and the remaining four split what is left.
- 60%National Airspace System
- 28%Late-arriving aircraft
- 9%Carrier
- 3%Extreme weather
60% 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 29,000 minutes out of 49,000, against a national NAS share of 21%. The split is drawn from 49,001 reported delay minutes.
Cancellations are rare at 0.56%, below the national 1.89% 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
10.0% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection here, and two hours if the onward flight is on a separate ticket.
At 447 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 5am–8am window matters as much as it does.
The return leg is a different operation and performs like one: it runs 72.8% on time across 2,666 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 2,666 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 SFO
Put together: the calendar is the biggest lever here, not the carrier or the hour. March runs 89.3% on time and May 49.1%, a swing of 40 points. If the dates move at all, move them out of May before you think about anything else. 2,650 completed flights over 12 months sit behind that.
Related
Where to go next
- SAN to SFO, every carrier
- United on SFO to SAN, the return leg
- SkyWest Airlines on SAN to SFO59.8%
- Alaska Airlines on SAN to SFO53.1%
- Southwest Airlines on SAN to SFO52.4%
- Frontier Airlines on SAN to SFO37.9%
- United Airlines network-wide record
- San Diego International (SAN) delay statistics
- San Francisco International (SFO) delay statistics
- How often a connection fails at the major US hubs
- The best time of day to fly, according to 7.05 million flight records
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.