Carrier route record
WNMKE→PHX
Southwest Airlines · Milwaukee to Phoenix
- Flights
- 981
- Period
- July 2025 to June 2026
- Share of route
- 67%
- Carriers
- 3
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on MKE to PHX lands a B+, 2 points better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about 55 minutes on average. That is a workable record, not a spotless one. That rests on 981 flights, with a median arrival 3 minutes early.
The US average over the same twelve months is 77.6%, so there is little to separate Southwest on MKE to PHX from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
79.3%
Arrivals under 15 minutes late, of 975 completed flights
Avg delay
54 min
Across delayed arrivals only, not all flights
Cancelled
0.41%
National rate is 1.81%
Whole route
78.8%
Every carrier on MKE to PHX, 1,471 flights
These figures cover 981 flights between July 2025 and June 2026. The median arrival is 3 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.
Carrier by carrier
Southwest against every carrier on MKE to PHX
Southwest flew 981 of the 1,471 flights on MKE to PHX, most of the route. Its 79.3% on time is about level with the route as a whole at 78.8%. Ranked by on-time rate it is first of three carriers on the route, where the range runs from Southwest at 79.3% to Frontier at 50.0%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
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 |
|---|---|---|---|---|---|
| Southwest Airlines (this page) | 981 | 79.3% | 54 min | 0.41% | B+ |
| American Airlines | 486 | 77.9% | 103 min | 1.85% | B |
| Frontier Airlinesthin sample | 4 | 50.0% | 55 min | 0.00% | F+ |
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 25 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am332 flights91.2%
- 8am–11am46 flights89.1%
- 11am–2pm167 flights81.3%
- 2pm–5pm119 flights72.3%
- 5pm–8pm250 flights66.1%
- 8pm–5am67 flights69.2%
Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 91.2% of the time, against 66.1% for the evening window. That is 25 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5am–8am window is the busiest, with 332 flights scheduled in it.
Across the year
Southwest on MKE to PHX through the year
December is the weak month at 64.8% on time, against 93.3% in October. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. March was the busiest month here, with 103 flights.
Across the week, Friday is the strongest day at 84.6% on time and Saturday the weakest at 74.3%. 10 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 52% of the 11,000 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.
- 52%Late-arriving aircraft
- 27%Carrier
- 19%National Airspace System
- 3%Extreme weather
- 0%Security
52% 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 11,000 reported delay minutes here, that single category outweighs weather by 20 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 10,996 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 91.2% on time here.
Cancellations are rare at 0.41%, 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
6.1% 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 about 55 minutes, which a normal layover absorbs.
The 1,460 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 69.6% on time across 979 flights, 10 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 10 points of difference.
One caution: this is a thin sample. 981 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 MKE to PHX
Put together: treat all of this as provisional. 981 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 79.3% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 975 completed flights over 12 months sit behind that.
Related
Where to go next
- MKE to PHX, every carrier
- Southwest on PHX to MKE, the return leg
- American Airlines on MKE to PHX77.9%
- Southwest Airlines network-wide record
- 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.