Route reliability record
PHX→SFO
Phoenix to San Francisco
- Flights
- 4,644
- Period
- July 2025 to June 2026
- Distance
- 651 mi
- Carriers
- 6
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 4,644 flights, of which United Airlines flew 1,444 at 73.1% on time.
United Airlines is the most reliable of the four carriers covered here at 73.1% on time across 1,444 flights.
Key figures
On time
67.6%
Arrivals under 15 minutes late, of 4,616 completed flights
Avg delay
64 min
Across delayed arrivals only, not all flights
Cancelled
0.56%
National rate is 1.81%
Best carrier
United
73.1% on time across 1,444 flights
These figures cover 4,644 flights between July 2025 and June 2026. Beyond the headline rate, 11.5% 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 PHX to SFO
The choice of carrier is not cosmetic here. United Airlines arrives on time 73.1% of the time; Southwest Airlines manages 60.5%. Sample sizes sit next to every figure, because a two-point gap across 1,079 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Envoy Airthin sample | 1 | 100.0% | — | 0.00% | A+ |
| United Airlines | 1,444 | 73.1% | 62 min | 0.55% | C+ |
| Frontier Airlinesthin sample | 263 | 68.6% | 61 min | 0.76% | C+ |
| SkyWest Airlines | 538 | 68.5% | 65 min | 0.19% | C+ |
| American Airlines | 1,319 | 66.9% | 76 min | 0.91% | C+ |
| Southwest Airlines | 1,079 | 60.5% | 55 min | 0.28% | D+ |
The spread between United and Southwest is 13 points, wide enough that it should decide the booking. On a hundred trips that is 13 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 18 points, against 13 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am692 flights74.1%
- 8am–11am1,002 flights70.9%
- 11am–2pm589 flights65.2%
- 2pm–5pm825 flights72.6%
- 5pm–8pm958 flights63.7%
- 8pm–5am578 flights56.0%
Scale runs 50% to 80%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 56.0% on time, against 74.1% 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 8am–11am window is the busiest, with 1,002 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 46 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.
June is the worst month at 37.3% on time, 46 points below March, the best at 83.2%. 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. March was the busiest month here, with 454 flights.
Across the week, Tuesday is the strongest day at 76.8% on time and Monday the weakest at 61.5%. 15 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 96,000 reported delay minutes.
- 40%National Airspace System
- 35%Late-arriving aircraft
- 23%Carrier
- 2%Extreme weather
- 0%Security
35% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 96,000 reported delay minutes here, that single category outweighs weather by 16 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 96,260 reported delay minutes.
40% 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 38,000 minutes out of 96,000, against a national NAS share of 21%.
Cancellations are rare at 0.56%, 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 actually costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 11.5% 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.
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. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
The return leg is a different operation and performs like one: it runs 74.4% on time across 4,643 flights, 7 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 7 points of difference.
The sample behind these figures is 4,644 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 83.2% on time and June 37.3%, a swing of 46 points. If the dates move at all, move them out of June before you think about anything else. 4,616 completed flights over 12 months sit behind that.
Common questions
PHX to SFO questions
How often is PHX 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 32.4% of the 4,644 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on PHX to SFO?
United Airlines leads at 73.1% on time across 1,444 flights. Southwest Airlines is at the other end on 60.5%, a gap of 13 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 PHX to SFO?
The 5am–8am departure window is the strongest at 74.1% on time. The 8pm–5am window is the weakest at 56.0%, 18 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 June delays on PHX to SFO?
June is the weakest month at 37.3% on time, compared with 83.2% in March. Across the year that is 46 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 PHX — the return legseparate record
- Phoenix Sky Harbor International (PHX) delay statistics
- San Francisco International (SFO) delay statistics
- Envoy Air on-time record100.0%
- United Airlines on-time record73.1%
- Frontier Airlines on-time record68.6%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Direction matters. PHX to SFO and SFO to PHX 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, July 2025 to June 2026. Updated monthly. How this data is collected.