Carrier route record
WNSFO→PHX
Southwest Airlines · San Francisco to Phoenix
- Flights
- 1,076
- Period
- September 2025 to August 2026
- Share of route
- 23%
- Carriers
- 5
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on SFO to PHX draws a D+. Roughly one flight in two 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 1,076 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
58.8%
Arrivals under 15 minutes late, of 1,067 completed flights
Avg delay
57 min
Across delayed arrivals only, not all flights
Cancelled
0.56%
National rate is 1.89%
Whole route
72.8%
Every carrier on SFO to PHX, 4,727 flights
These figures cover 1,076 flights between September 2025 and August 2026. Beyond the headline rate, 13.0% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
Southwest against every carrier on SFO to PHX
Southwest flew 1,076 of the 4,727 flights on SFO to PHX, about 23% of it. Its 58.8% on time is 14 points worse than the route as a whole, which runs 72.8%. Ranked by on-time rate it is last 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; American Airlines manages 73.2%. Sample sizes sit next to every figure, because a two-point gap across 1,313 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 | 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 (this page) | 1,076 | 58.8% | 57 min | 0.56% | D+ |
The spread between SkyWest and American is 12 points, wide enough that it should decide the booking. On a hundred trips that is 12 more arrivals inside the on-time window.
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Departure window
When Southwest runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 63 points, against 12 points between the best and worst carrier.
- 5am–8am335 flights93.7%
- 8am–11am123 flights56.1%
- 11am–2pm248 flights41.2%
- 2pm–5pm241 flights44.4%
- 5pm–8pm111 flights31.2%
- 8pm–5am18 flights—
Scale runs 25% to 100%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 31.2% on time, against 93.7% 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 335 flights scheduled in it.
Across the year
Southwest on SFO to PHX through the year
Delays peak in May, when the on-time rate falls to 38.0%. January is the strongest month at 84.2%. Moving a flexible trip across that boundary buys 46 points. January was the busiest month here, with 95 flights.
Across the week, Tuesday is the strongest day at 67.5% on time and Sunday the weakest at 52.6%, a spread of 15 points.
Arrival by arrival
How late Southwest on SFO to PHX runs when it is late
The 440 late arrivals split 149 under half an hour, 152 between 30 and 60 minutes, and 139 an hour or more.
- 15+ min early115 flights10.8%
- Within 15 min512 flights48.0%
- 15–29 min late149 flights14.0%
- 30–59 min late152 flights14.2%
- 1–2 hours late95 flights8.9%
- 2+ hours late44 flights4.1%
Scale runs 0% to 100%.
Share of 1,067 completed flights by arrival against schedule.
Time lost at the gate mostly stays lost. Of 463 departures that left 15 minutes late or more, only 50 made it up before arrival. 27 flights left on time and still arrived late.
The worst days
Worst days for Southwest on SFO to PHX
The latest arrival of the period was on 25 December 2025, 7 hours 22 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on five of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 25 December 2025 | 7 hours 22 minutes | Carrier |
| 24 December 2025 | 6 hours 27 minutes | Carrier |
| 17 April 2026 | 6 hours 15 minutes | Carrier |
| 18 June 2026 | 5 hours 35 minutes | Carrier |
| 15 May 2026 | 4 hours 37 minutes | Carrier |
Delay causes
Why Southwest runs late on this route
Late-arriving aircraft accounts for 60% of the 25,000 delay minutes carriers reported here, and the remaining four split what is left.
- 60%Late-arriving aircraft
- 31%Carrier
- 9%National Airspace System
- 0%Extreme weather
60% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 25,000 reported delay minutes here, that single category outweighs weather by 60 to one. The split is drawn from 25,186 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 93.7% on time here.
Cancellations are rare at 0.56%, 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
13.0% 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.
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 runs 57.7% on time across 1,076 flights, within about a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
One caution: this is a thin sample. 1,076 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 Southwest on SFO to PHX
Put together: treat all of this as provisional. 1,076 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 58.8% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 1,067 completed flights over 12 months sit behind that.
Related
Where to go next
- SFO to PHX, every carrier
- Southwest on PHX to SFO, the return leg
- SkyWest Airlines on SFO to PHX85.2%
- United Airlines on SFO to PHX79.9%
- American Airlines on SFO to PHX73.2%
- Frontier Airlines on SFO to PHX61.1%
- Southwest Airlines network-wide record
- San Francisco International (SFO) delay statistics
- Phoenix Sky Harbor International (PHX) delay statistics
- Why the first flight of the morning is statistically safest
- Same route, different airline: where the carrier you pick matters most
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.