Carrier route record
UALAS→SFO
United Airlines · Las Vegas to San Francisco
- Flights
- 2,756
- Period
- July 2025 to June 2026
- Share of route
- 45%
- Carriers
- 5
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on LAS 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 2,756 flights. The strongest carrier on the route with a full sample, Alaska Airlines, flew 1,116 at 66.5% on time.
The national on-time rate over the same period is 77.6%, so United on LAS 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
67.5%
Arrivals under 15 minutes late, of 2,744 completed flights
Avg delay
61 min
Across delayed arrivals only, not all flights
Cancelled
0.44%
National rate is 1.81%
Whole route
62.8%
Every carrier on LAS to SFO, 6,060 flights
These figures cover 2,756 flights between July 2025 and June 2026. Beyond the headline rate, 10.5% 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
United against every carrier on LAS to SFO
United flew 2,756 of the 6,060 flights on LAS to SFO, about 45% of it. Its 67.5% on time is 5 points better than the route as a whole, which runs 62.8%. Ranked by on-time rate it is number two of five carriers on the route, where the range runs from SkyWest at 100.0% to Southwest at 48.8%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The choice of carrier is not cosmetic here. Alaska Airlines arrives on time 66.5% of the time; Southwest Airlines manages 48.8%. Sample sizes sit next to every figure, because a two-point gap across 1,310 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlinesthin sample | 3 | 100.0% | — | 0.00% | A+ |
| United Airlines (this page) | 2,756 | 67.5% | 61 min | 0.44% | C+ |
| Alaska Airlines | 1,116 | 66.5% | 52 min | 1.08% | C |
| Frontier Airlines | 875 | 64.3% | 70 min | 1.37% | D |
| Southwest Airlines | 1,310 | 48.8% | 54 min | 0.38% | F+ |
The spread between Alaska and Southwest is 18 points, wide enough that it should decide the booking. On a hundred trips that is 18 more arrivals inside the on-time window.
Flight by flight
United flight numbers on LAS to SFO
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 46 points, against 18 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am659 flights81.4%
- 8am–11am255 flights65.5%
- 11am–2pm684 flights69.8%
- 2pm–5pm403 flights70.8%
- 5pm–8pm531 flights58.8%
- 8pm–5am224 flights35.9%
Scale runs 25% to 85%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 35.9% on time, against 81.4% 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 684 flights scheduled in it.
Across the year
United on LAS to SFO through the year
Delays peak in May, when the on-time rate falls to 43.8%. March is the strongest month at 86.7%. Moving a flexible trip across that boundary buys 43 points. June was the busiest month here, with 255 flights.
Across the week, Saturday is the strongest day at 76.2% on time and Thursday the weakest at 61.9%. 14 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 58% of the 54,000 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.
- 58%National Airspace System
- 30%Late-arriving aircraft
- 11%Carrier
- 1%Extreme weather
58% 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 31,000 minutes out of 54,000, against a national NAS share of 21%. The split is drawn from 54,122 reported delay minutes.
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 81.4% on time here.
Cancellations are rare at 0.44%, 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
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 10.5% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.
At 414 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 79.6% on time across 2,757 flights, 12 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 12 points of difference.
The sample behind these figures is 2,756 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 LAS to SFO
Put together: the calendar is the biggest lever here, not the carrier or the hour. March runs 86.7% on time and May 43.8%, a swing of 43 points. If the dates move at all, move them out of May before you think about anything else. 2,744 completed flights over 12 months sit behind that.
Related
Where to go next
- LAS to SFO, every carrier
- United on SFO to LAS, the return leg
- Alaska Airlines on LAS to SFO66.5%
- Frontier Airlines on LAS to SFO64.3%
- Southwest Airlines on LAS to SFO48.8%
- United Airlines network-wide record
- Harry Reid International (LAS) delay statistics
- San Francisco International (SFO) delay statistics
- Same route, different airline: where the carrier you pick matters most
- How often a connection fails at the major US hubs
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.