Route reliability record
LAS→SFO
Las Vegas to San Francisco
- Flights
- 6,044
- Period
- June 2025 to May 2026
- Distance
- 414 mi
- Carriers
- 5
This route draws a C+. About one flight in three arrive 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 6,044 flights, of which United Airlines flew 2,733 at 70.6% on time.
United Airlines is the most reliable of the four carriers covered here at 70.6% on time across 2,733 flights.
Key figures
On time
65.8%
Arrivals under 15 minutes late, of 5,998 completed flights
Avg delay
57 min
Across delayed arrivals only, not all flights
Cancelled
0.73%
National rate is 1.80%
Best carrier
United
70.6% on time across 2,733 flights
These figures cover 6,044 flights between June 2025 and May 2026. Beyond the headline rate, 10.7% 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 LAS to SFO
The choice of carrier is not cosmetic here. United Airlines arrives on time 70.6% of the time; Southwest Airlines manages 53.4%. Sample sizes sit next to every figure, because a two-point gap across 1,309 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 | 2,733 | 70.6% | 59 min | 0.44% | C+ |
| Alaska Airlines | 1,133 | 68.4% | 51 min | 1.24% | C |
| Frontier Airlines | 866 | 65.8% | 68 min | 1.39% | C |
| Southwest Airlines | 1,309 | 53.4% | 53 min | 0.46% | F+ |
The spread between United and Southwest is 17 points, wide enough that it should decide the booking. On a hundred trips that is 17 more arrivals inside the on-time window.
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 32 points, against 17 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am1,099 flights83.0%
- 8am–11am900 flights61.8%
- 11am–2pm1,145 flights72.3%
- 2pm–5pm1,041 flights66.8%
- 5pm–8pm1,040 flights54.5%
- 8pm–5am819 flights50.6%
Scale runs 40% to 90%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 50.6% on time, against 83.0% 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.
Across the year
When delays peak on this route
This route's year swings by 43 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 May, when the on-time rate falls to 40.4%. March is the strongest month at 83.3%. Moving a flexible trip across that boundary buys 43 points.
Across the week, Saturday is the strongest day at 75.7% on time and Sunday the weakest at 61.0%. 15 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
One category carries most of the weight here. National Airspace System accounts for 51% of the 118,000 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.
- 51%National Airspace System
- 31%Late-arriving aircraft
- 16%Carrier
- 1%Extreme weather
- 0%Security
51% 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 60,000 minutes out of 118,000, against a national NAS share of 21%.
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 83.0% on time here.
Cancellations are rare at 0.73%, below the national 1.80% 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 actually costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 10.7% of arrivals land a full hour or more behind schedule, against 8.2% 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 75.7% on time across 6,055 flights, 10 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 10 points of difference.
The sample behind these figures is 6,044 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 this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. March runs 83.3% on time and May 40.4%, a swing of 43 points. If the dates move at all, move them out of May before you think about anything else.
Common questions
LAS to SFO questions
How often is LAS to SFO delayed?
About one flight in three arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 34.2% of the 6,044 flights in this analysis, against 22.6% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on LAS to SFO?
United Airlines leads at 70.6% on time across 2,733 flights. Southwest Airlines is at the other end on 53.4%, a gap of 17 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 LAS to SFO?
The 5am–8am departure window is the strongest at 83.0% on time. The 8pm–5am window is the weakest at 50.6%, 32 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 May delays on LAS to SFO?
May is the weakest month at 40.4% on time, compared with 83.3% in March. Across the year that is 43 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
- SFO to LAS — the return legseparate record
- Harry Reid International (LAS) delay statistics
- San Francisco International (SFO) delay statistics
- SkyWest Airlines on-time record100.0%
- United Airlines on-time record70.6%
- Alaska Airlines on-time record68.4%
- The best time of day to fly, according to 7.05 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. LAS to SFO and SFO to LAS are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, June 2025 to May 2026. Updated monthly. How this data is collected.