Carrier route record

WNDSM→PHX

Southwest Airlines · Des Moines to Phoenix

Flights: 166
Period: July 2025 to June 2026
Share of route: 16%
Carriers: 5

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.

Southwest on DSM to PHX sits in the middle of the pack with a C. Close to three flights in four arrive on time by the DOT's definition, 4 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 166 flights, with a median arrival 1 minute late.

The US average over the same twelve months is 77.6%, so there is little to separate Southwest on DSM to PHX from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

73.8%

Arrivals under 15 minutes late, of 164 completed flights

Avg delay

59 min

Across delayed arrivals only, not all flights

Cancelled

1.20%

National rate is 1.81%

Whole route

80.6%

Every carrier on DSM to PHX, 1,064 flights

These figures cover 166 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 DSM to PHX

Southwest flew 166 of the 1,064 flights on DSM to PHX, about 16% of it. Its 73.8% on time is 7 points worse than the route as a whole, which runs 80.6%. Ranked by on-time rate it is last of five carriers on the route, where the range runs from Envoy at 93.6% to Southwest at 73.8%. Three 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.

On-time performance by carrier on DSM to PHX
Airline	Flights	On time	Avg delay	Cancelled	Grade
Envoy Airthin sample	47	93.6%	36 min	0.00%	A+
Frontier Airlinesthin sample	7	85.7%	142 min	0.00%	A+
SkyWest Airlinesthin sample	350	82.8%	66 min	1.43%	B
American Airlines	494	80.0%	180 min	1.82%	B
Southwest Airlines (this page)thin sample	166	73.8%	59 min	1.20%	C

Departure window

When Southwest runs best on this route

Departure time is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 166 flights.

5am–8am8 flights—
8am–11am—
11am–2pm86 flights76.2%
2pm–5pm67 flights67.2%
5pm–8pm—
8pm–5am5 flights—

Scale runs 60% to 80%. Rows with fewer than 30 flights show a dash.

The best window here is not the first bank but the 11am–2pm slot at 76.2% on time, ahead of 2pm–5pm at 67.2%. Where the curve peaks mid-day rather than at dawn, the constraint is usually congestion at one end rather than the aircraft's own rotation. The 11am–2pm window is the busiest, with 86 flights scheduled in it.

Across the year

Southwest on DSM to PHX through the year

Oct–Dec 202567 flights65.2%
Jan–Mar 202661 flights86.7%
Apr–Jun 202638 flights68.4%

Scale runs 55% to 90%. Rows with fewer than 30 flights show a dash.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 73.8% on time across 166 flights.

Southwest on DSM to PHX did not run the same all year. Its best quarter was Jan–Mar 2026 at 86.7% on time and its weakest Oct–Dec 2025 at 65.2%, a swing of 22 points on roughly 55 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.

Across the week, Sunday is the strongest day at 74.2% on time and Friday the weakest at 67.7%. 7 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 59% of the 2,544 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.

Late-arriving aircraft
59%
Carrier
20%
National Airspace System
17%
Extreme weather
4%
Security
1%

59% 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 2,544 reported delay minutes here, that single category outweighs weather by 17 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 2,544 reported delay minutes.

Cancellations sit at 1.20% against a national 1.81%, which is ordinary. Diversions add another 0.00%.

Connections and stage length

What a delay here costs

7.9% 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 an hour, which a normal layover absorbs.

The 1,149 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 runs 72.0% on time across 166 flights, within 2 points 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. 166 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 DSM to PHX

Put together: treat all of this as provisional. 166 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 73.8% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 164 completed flights over 12 months sit behind that.

Where to go next

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.

Key figures