Carrier route record
UAATL→SFO
United Airlines · Atlanta to San Francisco
- Flights
- 637
- Period
- July 2025 to June 2026
- Share of route
- 19%
- Carriers
- 3
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on ATL to SFO lands a B+, level with the national rate of 77.6%. Roughly one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 637 flights, with a median arrival 6 minutes early.
The US average over the same twelve months is 77.6%, so there is little to separate United on ATL to SFO from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
78.1%
Arrivals under 15 minutes late, of 635 completed flights
Avg delay
65 min
Across delayed arrivals only, not all flights
Cancelled
0.31%
National rate is 1.81%
Whole route
71.4%
Every carrier on ATL to SFO, 3,354 flights
These figures cover 637 flights between July 2025 and June 2026. Beyond the headline rate, 9.0% 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 ATL to SFO
United flew 637 of the 3,354 flights on ATL to SFO, about 19% of it. Its 78.1% on time is 7 points better than the route as a whole, which runs 71.4%. Ranked by on-time rate it is first of three carriers on the route, where the range runs from United at 78.1% to Frontier at 66.6%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines (this page) | 637 | 78.1% | 65 min | 0.31% | B+ |
| Delta Air Lines | 2,410 | 70.2% | 55 min | 0.62% | C+ |
| Frontier Airlinesthin sample | 307 | 66.6% | 71 min | 1.30% | C |
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 15 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am342 flights85.1%
- 8am–11am23 flights—
- 11am–2pm—
- 2pm–5pm—
- 5pm–8pm269 flights70.5%
- 8pm–5am3 flights—
Scale runs 60% to 90%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 85.1% of the time, against 70.5% for the evening window. That is 15 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5am–8am window is the busiest, with 342 flights scheduled in it.
Across the year
United on ATL to SFO through the year
June is the worst month at 59.6% on time, 35 points below March, the best at 94.3%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. November was the busiest month here, with 62 flights.
Across the week, Saturday is the strongest day at 85.3% on time and Sunday the weakest at 70.7%. 15 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 59% of the 9,075 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.
- 59%National Airspace System
- 21%Carrier
- 17%Late-arriving aircraft
- 3%Extreme weather
59% 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 5,393 minutes out of 9,075, against a national NAS share of 21%. The split is drawn from 9,075 reported delay minutes.
Cancellations are rare at 0.31%, 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. 9.0% 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 2,139 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 86.5% on time across 637 flights, 8 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 8 points of difference.
One caution: this is a thin sample. 637 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.
What to do with this
Booking United on ATL to SFO
Put together: treat all of this as provisional. 637 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 78.1% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 635 completed flights over 12 months sit behind that.
Related
Where to go next
- ATL to SFO, every carrier
- United on SFO to ATL, the return leg
- Delta Air Lines on ATL to SFO70.2%
- Frontier Airlines on ATL to SFO66.6%
- United Airlines network-wide record
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- San Francisco International (SFO) delay statistics
- The best time of day to fly, according to 7.04 million flight records
- 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.