Carrier route record
WNSEA→PHX
Southwest Airlines · Seattle to Phoenix
- Flights
- 1,036
- Period
- July 2025 to June 2026
- Share of route
- 14%
- Carriers
- 7
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on SEA to PHX sits in the middle of the pack with a C+. About seven flights in ten arrive on time by the DOT's definition, 9 points worse than the national rate of 77.6%. The late ones land roughly 45 minutes behind schedule. That rests on 1,036 flights. The strongest carrier on the route with a full sample, Envoy Air, flew 691 at 86.9% on time.
Envoy Air is the most reliable of the four carriers covered here at 86.9% on time across 691 flights.
Key figures
On time
69.0%
Arrivals under 15 minutes late, of 1,026 completed flights
Avg delay
47 min
Across delayed arrivals only, not all flights
Cancelled
0.68%
National rate is 1.81%
Whole route
79.2%
Every carrier on SEA to PHX, 7,268 flights
These figures cover 1,036 flights between July 2025 and June 2026. On-time means an arrival less than 15 minutes after the scheduled gate time, the same threshold the Department of Transportation uses in its own reports. Cancelled and diverted flights are excluded from the on-time rate and counted separately, which is why the cancellation column matters on its own.
Carrier by carrier
Southwest against every carrier on SEA to PHX
Southwest flew 1,036 of the 7,268 flights on SEA to PHX, about 14% of it. Its 69.0% on time is 10 points worse than the route as a whole, which runs 79.2%. Ranked by on-time rate it is last of seven carriers on the route, where the range runs from Envoy at 86.9% to Southwest at 69.0%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The choice of carrier is not cosmetic here. Envoy Air arrives on time 86.9% of the time; Alaska Airlines manages 79.0%. Sample sizes sit next to every figure, because a two-point gap across 2,906 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Envoy Air | 691 | 86.9% | 71 min | 0.00% | A+ |
| American Airlinesthin sample | 199 | 84.8% | 81 min | 0.50% | B+ |
| Delta Air Lines | 1,765 | 82.6% | 65 min | 0.85% | B+ |
| SkyWest Airlines | 506 | 80.2% | 75 min | 0.59% | B+ |
| Alaska Airlines | 2,906 | 79.0% | 45 min | 0.65% | B+ |
| Frontier Airlinesthin sample | 165 | 70.4% | 126 min | 3.64% | C− |
| Southwest Airlines (this page) | 1,036 | 69.0% | 47 min | 0.68% | C+ |
Envoy leads Alaska by 8 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
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 50 points, against 8 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am350 flights94.5%
- 8am–11am121 flights69.2%
- 11am–2pm234 flights56.0%
- 2pm–5pm143 flights53.9%
- 5pm–8pm145 flights50.3%
- 8pm–5am43 flights44.2%
Scale runs 35% to 100%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 44.2% on time, against 94.5% 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 350 flights scheduled in it.
Across the year
Southwest on SEA to PHX through the year
June is the worst month at 53.4% on time, 33 points below January, the best at 86.4%. 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. July was the busiest month here, with 104 flights.
Across the week, Tuesday is the strongest day at 74.6% on time and Thursday the weakest at 63.0%. 12 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Southwest runs late on this route
One category carries most of the weight here. Late-arriving aircraft accounts for 56% of the 15,000 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.
- 56%Late-arriving aircraft
- 31%Carrier
- 14%National Airspace System
- 0%Extreme weather
56% 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 15,000 reported delay minutes here, that single category outweighs weather by 56 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 14,992 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 94.5% on time here.
Cancellations are rare at 0.68%, 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
6.4% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last roughly 45 minutes, which a normal layover absorbs.
The 1,107 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 64.8% on time across 1,037 flights, 4 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 4 points of difference.
One caution: this is a thin sample. 1,036 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 SEA to PHX
Put together: treat all of this as provisional. 1,036 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 69.0% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 1,026 completed flights over 12 months sit behind that.
Related
Where to go next
- SEA to PHX, every carrier
- Southwest on PHX to SEA, the return leg
- Envoy Air on SEA to PHX86.9%
- American Airlines on SEA to PHX84.8%
- Delta Air Lines on SEA to PHX82.6%
- SkyWest Airlines on SEA to PHX80.2%
- Alaska Airlines on SEA to PHX79.0%
- Frontier Airlines on SEA to PHX70.4%
- Southwest Airlines network-wide record
- Seattle-Tacoma International (SEA) delay statistics
- Phoenix Sky Harbor International (PHX) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
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.