Route reliability record
DEN→COS
Denver to Colorado Springs
- Flights
- 5,039
- Period
- July 2025 to June 2026
- Distance
- 73 mi
- Carriers
- 3
This route 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 5,039 flights, of which United Airlines flew 614 at 77.3% on time.
United Airlines is the most reliable of the three carriers covered here at 77.3% on time across 614 flights.
Key figures
On time
75.8%
Arrivals under 15 minutes late, of 4,962 completed flights
Avg delay
67 min
Across delayed arrivals only, not all flights
Cancelled
1.45%
National rate is 1.81%
Best carrier
United
77.3% on time across 614 flights
These figures cover 5,039 flights between July 2025 and June 2026. Beyond the headline rate, 9.2% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Carrier by carrier
Which airline is most reliable on DEN to COS
The three carriers here are closely matched: 4 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 614 | 77.3% | 69 min | 0.98% | B+ |
| SkyWest Airlines | 3,283 | 76.5% | 72 min | 1.89% | B |
| Southwest Airlines | 1,142 | 72.9% | 54 min | 0.44% | C+ |
No carrier stands out. United tops the table at 77.3%, 4 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 21 points, against 4 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am154 flights84.4%
- 8am–11am873 flights85.4%
- 11am–2pm950 flights82.6%
- 2pm–5pm879 flights74.9%
- 5pm–8pm989 flights64.9%
- 8pm–5am1,194 flights71.8%
Scale runs 55% to 90%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 64.9% on time, against 85.4% 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 8pm–5am window is the busiest, with 1,194 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 28 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
July is the worst month at 58.4% on time, 28 points below November, the best at 86.5%. 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 466 flights.
Across the week, Wednesday is the strongest day at 79.6% on time and Friday the weakest at 71.5%. 8 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
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 81,000 reported delay minutes.
- 40%Late-arriving aircraft
- 33%Carrier
- 18%National Airspace System
- 8%Extreme weather
- 0%Security
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 81,000 reported delay minutes here, that single category outweighs weather by 5 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 80,682 reported delay minutes.
The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 85.4% on time here.
Cancellations sit at 1.45% against a national 1.81%, which is ordinary. Diversions add another 0.08%.
Connections and stage length
What a delay here actually costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 9.2% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.
At 73 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 78.8% on time across 5,038 flights, 3 points above 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 3 points of difference.
The sample behind these figures is 5,039 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 this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. November runs 86.5% on time and July 58.4%, a swing of 28 points. If the dates move at all, move them out of July before you think about anything else. 4,962 completed flights over 12 months sit behind that.
Common questions
DEN to COS questions
How often is DEN to COS delayed?
About one flight in four arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 24.2% of the 5,039 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on DEN to COS?
United Airlines leads at 77.3% on time across 614 flights. Southwest Airlines is at the other end on 72.9%, a gap of 4 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on DEN to COS?
The 8am–11am departure window is the strongest at 85.4% on time. The 5pm–8pm window is the weakest at 64.9%, 21 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are July delays on DEN to COS?
July is the weakest month at 58.4% on time, compared with 86.5% in November. Across the year that is 28 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- COS to DEN — the return legseparate record
- Denver International (DEN) delay statistics
- United Airlines on-time record77.3%
- SkyWest Airlines on-time record76.5%
- Southwest Airlines on-time record72.9%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Direction matters. DEN to COS and COS to DEN are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.