Carrier route record
UAPHL→SFO
United Airlines · Philadelphia to San Francisco
- Flights
- 750
- Period
- September 2025 to August 2026
- Share of route
- 36%
- Carriers
- 2
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with United Airlines.
United on PHL to SFO sits in the middle of the pack with a C+. About seven flights in ten arrive on time by the DOT's definition, 8 points worse than the national rate of 77.3%. The late ones land a little over an hour behind schedule. That rests on 750 flights, with a median arrival 1 minute early.
The national on-time rate over the same period is 77.3%, so United on PHL to SFO runs 8 points behind the country as a whole. Across a thousand flights that is about 76 extra late arrivals.
Key figures
On time
69.7%
Arrivals under 15 minutes late, of 746 completed flights
Avg delay
81 min
Across delayed arrivals only, not all flights
Cancelled
0.53%
National rate is 1.89%
Whole route
71.9%
Every carrier on PHL to SFO, 2,085 flights
These figures cover 750 flights between September 2025 and August 2026. Beyond the headline rate, 12.3% 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 PHL to SFO
United flew 750 of the 2,085 flights on PHL to SFO, about 36% of it. Its 69.7% on time is 2 points worse than the route as a whole, which runs 71.9%. Ranked by on-time rate it is last of two carriers on the route, where the range runs from American at 73.2% to United at 69.7%.
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 |
|---|---|---|---|---|---|
| American Airlines | 1,335 | 73.2% | 80 min | 1.65% | C |
| United Airlines (this page) | 750 | 69.7% | 81 min | 0.53% | C+ |
Flight by flight
United flight numbers on PHL 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 28 points, against half a point between the best and worst carrier.
- 5am–8am271 flights83.8%
- 8am–11am221 flights68.3%
- 11am–2pm—
- 2pm–5pm—
- 5pm–8pm258 flights56.0%
- 8pm–5am—
Scale runs 50% to 90%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 56.0% on time, against 83.8% 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 271 flights scheduled in it.
Across the year
United on PHL to SFO through the year
June is the worst month at 53.7% on time, 35 points below September, the best at 88.5%. 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. May was the busiest month here, with 83 flights.
Across the week, Saturday is the strongest day at 83.5% on time and Thursday the weakest at 59.5%, a spread of 24 points.
Arrival by arrival
How late United on PHL to SFO runs when it is late
The 226 late arrivals split 68 under half an hour, 66 between 30 and 60 minutes, and 92 an hour or more.
- 15+ min early178 flights23.9%
- Within 15 min342 flights45.8%
- 15–29 min late68 flights9.1%
- 30–59 min late66 flights8.8%
- 1–2 hours late57 flights7.6%
- 2+ hours late35 flights4.7%
Scale runs 0% to 100%.
Share of 746 completed flights by arrival against schedule.
41 of 208 late departures made up the time and arrived on time, 20% of them. In the other direction, 59 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 PHL to SFO
The latest arrival of the period was on 7 August 2026, 23 hours 39 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The five worst days are spread across August, June, March and May, with no single month standing out.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 7 August 2026 | 23 hours 39 minutes | Late-arriving aircraft |
| 14 June 2026 | 15 hours 57 minutes | Extreme weather |
| 15 March 2026 | 15 hours 37 minutes | Extreme weather |
| 11 June 2026 | 4 hours 55 minutes | National Airspace System |
| 24 May 2026 | 4 hours 34 minutes | Late-arriving aircraft |
Delay causes
Why United runs late on this route
National Airspace System accounts for 54% of the 18,000 delay minutes carriers reported here, and the remaining four split what is left.
- 54%National Airspace System
- 20%Late-arriving aircraft
- 15%Carrier
- 11%Extreme weather
54% 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 9,927 minutes out of 18,000, against a national NAS share of 21%. The split is drawn from 18,326 reported delay minutes.
Cancellations are rare at 0.53%, 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
12.3% 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 2,522 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 84.8% on time across 749 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.
One caution: this is a thin sample. 750 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 PHL to SFO
Put together: treat all of this as provisional. 750 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 69.7% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 746 completed flights over 12 months sit behind that.
Related
Where to go next
- PHL to SFO, every carrier
- United on SFO to PHL, the return leg
- American Airlines on PHL to SFO73.2%
- United Airlines network-wide record
- Philadelphia International (PHL) 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.