Carrier route record

WNPIT→DEN

Southwest Airlines · Pittsburgh to Denver

Flights: 766
Period: July 2025 to June 2026
Share of route: 45%
Carriers: 3

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

Southwest on PIT to DEN sits in the middle of the pack with a B+. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 766 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 PIT to DEN from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

75.9%

Arrivals under 15 minutes late, of 760 completed flights

Avg delay

61 min

Across delayed arrivals only, not all flights

Cancelled

0.78%

National rate is 1.81%

Whole route

81.6%

Every carrier on PIT to DEN, 1,698 flights

These figures cover 766 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 PIT to DEN

Southwest flew 766 of the 1,698 flights on PIT to DEN, about 45% of it. Its 75.9% on time is 6 points worse than the route as a whole, which runs 81.6%. Ranked by on-time rate it is last of three carriers on the route, where the range runs from United at 86.8% to Southwest at 75.9%. 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.

On-time performance by carrier on PIT to DEN
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlines	883	86.8%	61 min	0.68%	A+
Frontier Airlinesthin sample	49	77.6%	105 min	0.00%	B+
Southwest Airlines (this page)	766	75.9%	61 min	0.78%	B+

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 37 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–8am270 flights94.1%
8am–11am37 flights94.4%
11am–2pm93 flights81.5%
2pm–5pm51 flights58.8%
5pm–8pm266 flights57.6%
8pm–5am49 flights68.8%

Scale runs 50% to 100%. Rows with fewer than 30 flights show a dash.

The 5pm–8pm window is where this operation falls apart: 57.6% on time, against 94.4% for the 8am–11am 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 270 flights scheduled in it.

Across the year

Southwest on PIT to DEN through the year

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

July is the worst month at 66.7% on time, 21 points below April, the best at 87.7%. 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 84 flights.

Across the week, Wednesday is the strongest day at 80.6% on time and Saturday the weakest at 71.1%. 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 45% 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.

Late-arriving aircraft
45%
National Airspace System
34%
Carrier
20%
Extreme weather
2%

45% 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 23 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 11,153 reported delay minutes.

34% 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 3,773 minutes out of 11,000, against a national NAS share of 21%.

Cancellations are rare at 0.78%, 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

7.5% 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 1,290 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 63.7% on time across 765 flights, 12 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 12 points of difference.

One caution: this is a thin sample. 766 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 PIT to DEN

Put together: treat all of this as provisional. 766 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 75.9% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 760 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