Carrier route record
UASFO→PHX
United Airlines · San Francisco to Phoenix
- Flights
- 1,488
- Period
- September 2025 to August 2026
- Share of route
- 31%
- Carriers
- 5
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with United Airlines.
United on SFO to PHX lands a B+, 3 points better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 1,488 flights. The strongest carrier on the route with a full sample, SkyWest Airlines, flew 572 at 85.2% on time.
SkyWest Airlines is the most reliable of the three carriers covered here at 85.2% on time across 572 flights.
Key figures
On time
79.9%
Arrivals under 15 minutes late, of 1,471 completed flights
Avg delay
59 min
Across delayed arrivals only, not all flights
Cancelled
0.40%
National rate is 1.89%
Whole route
72.8%
Every carrier on SFO to PHX, 4,727 flights
These figures cover 1,488 flights between September 2025 and August 2026. The median arrival is 6 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
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Carrier by carrier
United against every carrier on SFO to PHX
United flew 1,488 of the 4,727 flights on SFO to PHX, about 31% of it. Its 79.9% on time is 7 points better than the route as a whole, which runs 72.8%. Ranked by on-time rate it is number two of five carriers on the route, where the range runs from SkyWest at 85.2% to Southwest at 58.8%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 85.2% of the time; Southwest Airlines manages 58.8%. Sample sizes sit next to every figure, because a two-point gap across 1,076 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlines | 572 | 85.2% | 75 min | 0.70% | A+ |
| United Airlines (this page) | 1,488 | 79.9% | 59 min | 0.40% | B+ |
| American Airlines | 1,313 | 73.2% | 98 min | 0.91% | C+ |
| Frontier Airlinesthin sample | 278 | 61.1% | 106 min | 2.16% | D |
| Southwest Airlines | 1,076 | 58.8% | 57 min | 0.56% | D+ |
The spread between SkyWest and Southwest is 26 points, wide enough that it should decide the booking. On a hundred trips that is 26 more arrivals inside the on-time window.
Flight by flight
United flight numbers on SFO to PHX
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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 16 points, against 26 points between the best and worst carrier.
- 5am–8am124 flights90.9%
- 8am–11am255 flights81.2%
- 11am–2pm286 flights79.4%
- 2pm–5pm343 flights74.6%
- 5pm–8pm314 flights82.2%
- 8pm–5am166 flights77.6%
Scale runs 65% to 95%.
Book the early departure. Flights leaving between 5am–8am arrive on time 90.9% of the time, against 74.6% for the afternoon window. That is 16 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 2pm–5pm window is the busiest, with 343 flights scheduled in it.
Across the year
United on SFO to PHX through the year
August is the worst month at 67.0% on time, 25 points below March, the best at 92.1%. 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. December was the busiest month here, with 153 flights.
Across the week, Saturday is the strongest day at 86.5% on time and Sunday the weakest at 75.8%, a spread of 11 points.
Arrival by arrival
How late United on SFO to PHX runs when it is late
The 295 late arrivals split 102 under half an hour, 105 between 30 and 60 minutes, and 88 an hour or more.
- 15+ min early361 flights24.5%
- Within 15 min815 flights55.4%
- 15–29 min late102 flights6.9%
- 30–59 min late105 flights7.1%
- 1–2 hours late60 flights4.1%
- 2+ hours late28 flights1.9%
Scale runs 0% to 100%.
Share of 1,471 completed flights by arrival against schedule.
51 of 279 late departures made up the time and arrived on time, 18% of them. 67 flights left on time and still arrived late.
The worst days
Worst days for United on SFO to PHX
The latest arrival of the period was on 31 December 2025, 6 hours 15 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The five worst days are spread across December, January, November and March, with no single month standing out.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 31 December 2025 | 6 hours 15 minutes | Carrier |
| 3 January 2026 | 5 hours 36 minutes | Late-arriving aircraft |
| 3 January 2026 | 5 hours 19 minutes | Late-arriving aircraft |
| 9 November 2025 | 4 hours 35 minutes | National Airspace System |
| 16 March 2026 | 4 hours 15 minutes | Carrier |
Delay causes
Why United runs late on this route
Late-arriving aircraft accounts for 50% of the 17,000 delay minutes carriers reported here, and the remaining four split what is left.
- 50%Late-arriving aircraft
- 25%Carrier
- 24%National Airspace System
- 0%Extreme weather
- 0%Security
50% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 17,000 reported delay minutes here, that single category outweighs weather by 50 to one. The split is drawn from 17,248 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 90.9% on time here.
Cancellations are rare at 0.40%, 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
6.0% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.
The 651 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty.
The return leg is a different operation and performs like one: it runs 67.7% on time across 1,489 flights, 12 points below 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 1,488 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 SFO to PHX
Put together: the calendar is the biggest lever here, not the carrier or the hour. March runs 92.1% on time and August 67.0%, a swing of 25 points. If the dates move at all, move them out of August before you think about anything else. 1,471 completed flights over 12 months sit behind that.
Related
Where to go next
- SFO to PHX, every carrier
- United on PHX to SFO, the return leg
- SkyWest Airlines on SFO to PHX85.2%
- American Airlines on SFO to PHX73.2%
- Frontier Airlines on SFO to PHX61.1%
- Southwest Airlines on SFO to PHX58.8%
- United Airlines network-wide record
- San Francisco International (SFO) delay statistics
- Phoenix Sky Harbor International (PHX) delay statistics
- Same route, different airline: where the carrier you pick matters most
- Why the first flight of the morning is statistically safest
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.