Carrier route record

WNDEN→AUS

Southwest Airlines · Denver to Austin

Flights: 2,346
Period: July 2025 to June 2026
Share of route: 44%
Carriers: 4

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

Southwest on DEN to AUS 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 2,346 flights. The strongest carrier on the route with a full sample, United Airlines, flew 1,914 at 79.9% on time.

United Airlines is the most reliable of the three carriers covered here at 79.9% on time across 1,914 flights.

On time

73.5%

Arrivals under 15 minutes late, of 2,330 completed flights

Avg delay

56 min

Across delayed arrivals only, not all flights

Cancelled

0.55%

National rate is 1.81%

Whole route

76.1%

Every carrier on DEN to AUS, 5,301 flights

These figures cover 2,346 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 DEN to AUS

Southwest flew 2,346 of the 5,301 flights on DEN to AUS, about 44% of it. Its 73.5% on time is 3 points worse than the route as a whole, which runs 76.1%. Ranked by on-time rate it is number three of four carriers on the route, where the range runs from United at 79.9% to Frontier at 72.3%.

The choice of carrier is not cosmetic here. United Airlines arrives on time 79.9% of the time; Frontier Airlines manages 72.3%. Sample sizes sit next to every figure, because a two-point gap across 550 flights means less than a ten-point one.

On-time performance by carrier on DEN to AUS
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlines	1,914	79.9%	64 min	0.63%	B+
SkyWest Airlines	491	78.5%	80 min	0.61%	B+
Southwest Airlines (this page)	2,346	73.5%	56 min	0.55%	C+
Frontier Airlines	550	72.3%	63 min	0.73%	C+

United leads Frontier 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 43 points, against 8 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am413 flights94.9%
8am–11am515 flights85.9%
11am–2pm417 flights70.7%
2pm–5pm345 flights63.6%
5pm–8pm407 flights60.4%
8pm–5am249 flights51.6%

Scale runs 45% to 100%. Rows with fewer than 30 flights show a dash.

The 8pm–5am window is where this operation falls apart: 51.6% on time, against 94.9% 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 515 flights scheduled in it.

Across the year

Southwest on DEN to AUS through the year

Darker means more delays. Figures are on-time percentages.January best, July worst

July is the worst month at 51.2% on time, 39 points below January, the best at 89.8%. 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. October was the busiest month here, with 220 flights.

Across the week, Wednesday is the strongest day at 80.5% on time and Friday the weakest at 69.9%. 11 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 53% of the 34,000 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.

Late-arriving aircraft
53%
Carrier
32%
National Airspace System
15%
Extreme weather
1%
Security
0%

53% 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 34,000 reported delay minutes here, that single category outweighs weather by 53 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 34,410 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 94.9% on time here.

Cancellations are rare at 0.55%, 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

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 775 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 72.7% on time across 2,356 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.

The sample behind these figures is 2,346 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 Southwest on DEN to AUS

Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 89.8% on time and July 51.2%, a swing of 39 points. If the dates move at all, move them out of July before you think about anything else. 2,330 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