Carrier route record

WNMTJ→DEN

Southwest Airlines · Montrose to Denver

Flights: 420
Period: July 2025 to June 2026
Share of route: 30%
Carriers: 3

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

Southwest on MTJ to DEN lands a B+, 3 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 a little over an hour on average. That is a workable record, not a spotless one. That rests on 420 flights, with a median arrival 11 minutes early.

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

On time

80.7%

Arrivals under 15 minutes late, of 419 completed flights

Avg delay

80 min

Across delayed arrivals only, not all flights

Cancelled

0.24%

National rate is 1.81%

Whole route

78.9%

Every carrier on MTJ to DEN, 1,416 flights

These figures cover 420 flights between July 2025 and June 2026. The median arrival is 11 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 MTJ to DEN

Southwest flew 420 of the 1,416 flights on MTJ to DEN, about 30% of it. Its 80.7% on time is 2 points better than the route as a whole, which runs 78.9%. Ranked by on-time rate it is first of three carriers on the route, where the range runs from Southwest at 80.7% to SkyWest at 75.7%. 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 MTJ to DEN
Airline	Flights	On time	Avg delay	Cancelled	Grade
Southwest Airlines (this page)	420	80.7%	80 min	0.24%	B+
United Airlines	886	78.5%	93 min	0.68%	B+
SkyWest Airlinesthin sample	110	75.7%	68 min	0.91%	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 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–8am—
8am–11am123 flights86.9%
11am–2pm202 flights84.7%
2pm–5pm87 flights62.1%
5pm–8pm8 flights—
8pm–5am—

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

Book the morning departure. Flights leaving between 8am–11am arrive on time 86.9% of the time, against 62.1% for the afternoon 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 11am–2pm window is the busiest, with 202 flights scheduled in it.

Across the year

Southwest on MTJ to DEN through the year

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

July is the worst month at 51.6% on time, 45 points below November, the best at 96.7%. 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. March was the busiest month here, with 58 flights.

Across the week, Thursday is the strongest day at 86.7% on time and Tuesday the weakest at 76.0%. 11 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Southwest runs late on this route

Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 6,476 reported delay minutes.

Late-arriving aircraft
40%
National Airspace System
40%
Carrier
20%
Security
1%
Extreme weather
0%

40% 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 6,476 reported delay minutes here, that single category outweighs weather by 40 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 6,476 reported delay minutes.

40% 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 2,571 minutes out of 6,476, against a national NAS share of 21%.

Cancellations are rare at 0.24%, 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 a little over an hour, which a normal layover absorbs.

At 197 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 8am–11am window matters as much as it does.

The return leg is a different operation and performs like one: it runs 73.9% on time across 421 flights, 7 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 7 points of difference.

One caution: this is a thin sample. 420 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 MTJ to DEN

Put together: treat all of this as provisional. 420 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 80.7% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 419 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