Carrier route record
UALAX→SFO
United Airlines · Los Angeles to San Francisco
- Flights
- 3,330
- Period
- September 2025 to August 2026
- Share of route
- 29%
- Carriers
- 7
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with United Airlines.
United on LAX to SFO draws a D+. Roughly 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 3,330 flights. The strongest carrier on the route with a full sample, SkyWest Airlines, flew 2,515 at 66.6% on time.
SkyWest Airlines is the most reliable of the five carriers covered here at 66.6% on time across 2,515 flights.
Key figures
On time
62.9%
Arrivals under 15 minutes late, of 3,326 completed flights
Avg delay
56 min
Across delayed arrivals only, not all flights
Cancelled
0.12%
National rate is 1.89%
Whole route
60.1%
Every carrier on LAX to SFO, 11,437 flights
These figures cover 3,330 flights between September 2025 and August 2026. Beyond the headline rate, 10.6% 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 LAX to SFO
United flew 3,330 of the 11,437 flights on LAX to SFO, about 29% of it. Its 62.9% on time is 3 points better than the route as a whole, which runs 60.1%. Ranked by on-time rate it is number three of seven carriers on the route, where the range runs from SkyWest at 66.6% to Frontier at 47.7%. One 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 66.6% of the time; Frontier Airlines manages 47.7%. Sample sizes sit next to every figure, because a two-point gap across 395 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlines | 2,515 | 66.6% | 58 min | 1.19% | C |
| American Airlinesthin sample | 302 | 63.9% | 76 min | 0.00% | D+ |
| United Airlines (this page) | 3,330 | 62.9% | 56 min | 0.12% | D+ |
| Delta Air Lines | 2,373 | 60.9% | 53 min | 1.56% | D |
| Alaska Airlines | 1,049 | 50.9% | 54 min | 0.67% | F+ |
| Southwest Airlines | 1,473 | 50.7% | 62 min | 0.34% | F+ |
| Frontier Airlines | 395 | 47.7% | 66 min | 2.28% | F |
The spread between SkyWest and Frontier is 19 points, wide enough that it should decide the booking. On a hundred trips that is 19 more arrivals inside the on-time window.
Flight by flight
United flight numbers on LAX 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 24 points, against 19 points between the best and worst carrier.
- 5am–8am463 flights75.1%
- 8am–11am503 flights51.0%
- 11am–2pm719 flights70.7%
- 2pm–5pm366 flights65.3%
- 5pm–8pm697 flights64.2%
- 8pm–5am582 flights50.9%
Scale runs 40% to 80%.
The 8pm–5am window is where this operation falls apart: 50.9% on time, against 75.1% 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 11am–2pm window is the busiest, with 719 flights scheduled in it.
Across the year
United on LAX to SFO through the year
Delays peak in May, when the on-time rate falls to 48.0%. March is the strongest month at 87.8%. Moving a flexible trip across that boundary buys 40 points. August was the busiest month here, with 305 flights.
Across the week, Tuesday is the strongest day at 73.0% on time and Thursday the weakest at 58.3%, a spread of 15 points.
Arrival by arrival
How late United on LAX to SFO runs when it is late
The 1,233 late arrivals split 421 under half an hour, 458 between 30 and 60 minutes, and 354 an hour or more.
- 15+ min early718 flights21.6%
- Within 15 min1,375 flights41.3%
- 15–29 min late421 flights12.7%
- 30–59 min late458 flights13.8%
- 1–2 hours late251 flights7.5%
- 2+ hours late103 flights3.1%
Scale runs 0% to 100%.
Share of 3,326 completed flights by arrival against schedule.
Time lost at the gate mostly stays lost. Of 774 departures that left 15 minutes late or more, only 84 made it up before arrival. In the other direction, 543 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 LAX to SFO
The latest arrival of the period was on 21 June 2026, 15 hours 54 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 21 June 2026 | 15 hours 54 minutes | Late-arriving aircraft |
| 12 September 2025 | 8 hours 1 minute | Carrier |
| 16 April 2026 | 6 hours 59 minutes | Late-arriving aircraft |
| 20 March 2026 | 6 hours 54 minutes | Late-arriving aircraft |
| 3 January 2026 | 6 hours 31 minutes | National Airspace System |
Delay causes
Why United runs late on this route
National Airspace System accounts for 68% of the 69,000 delay minutes carriers reported here, and the remaining four split what is left.
- 68%National Airspace System
- 21%Late-arriving aircraft
- 10%Carrier
- 0%Extreme weather
68% 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 47,000 minutes out of 69,000, against a national NAS share of 21%. The split is drawn from 68,647 reported delay minutes.
Cancellations are rare at 0.12%, 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
10.6% 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 337 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 77.7% on time across 3,335 flights, 15 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 15 points of difference.
The sample behind these figures is 3,330 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 LAX to SFO
Put together: the calendar is the biggest lever here, not the carrier or the hour. March runs 87.8% on time and May 48.0%, a swing of 40 points. If the dates move at all, move them out of May before you think about anything else. 3,326 completed flights over 12 months sit behind that.
Related
Where to go next
- LAX to SFO, every carrier
- United on SFO to LAX, the return leg
- SkyWest Airlines on LAX to SFO66.6%
- American Airlines on LAX to SFO63.9%
- Delta Air Lines on LAX to SFO60.9%
- Alaska Airlines on LAX to SFO50.9%
- Southwest Airlines on LAX to SFO50.7%
- Frontier Airlines on LAX to SFO47.7%
- United Airlines network-wide record
- Los Angeles International (LAX) delay statistics
- San Francisco International (SFO) delay statistics
- 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
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.