Route reliability record
COS→DEN
Colorado Springs to Denver
- Flights
- 5,038
- Period
- July 2025 to June 2026
- Distance
- 73 mi
- Carriers
- 3
This route lands a B, about a point better than the national rate of 77.6%. About one flight in five arrive 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 5,038 flights, of which SkyWest Airlines flew 3,282 at 81.3% on time.
SkyWest Airlines is the most reliable of the three carriers covered here at 81.3% on time across 3,282 flights.
Key figures
On time
78.8%
Arrivals under 15 minutes late, of 4,969 completed flights
Avg delay
71 min
Across delayed arrivals only, not all flights
Cancelled
1.33%
National rate is 1.81%
Best carrier
SkyWest
81.3% on time across 3,282 flights
These figures cover 5,038 flights between July 2025 and June 2026. The median arrival is 8 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
Which airline is most reliable on COS to DEN
The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 81.3% of the time; United Airlines manages 72.9%. Sample sizes sit next to every figure, because a two-point gap across 614 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlines | 3,282 | 81.3% | 75 min | 1.68% | B |
| Southwest Airlines | 1,142 | 75.0% | 57 min | 0.35% | B+ |
| United Airlines | 614 | 72.9% | 81 min | 1.30% | C |
SkyWest leads United by 8 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
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 30 points, against 8 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am1,429 flights88.9%
- 8am–11am1,084 flights84.4%
- 11am–2pm1,020 flights80.9%
- 2pm–5pm693 flights68.1%
- 5pm–8pm797 flights59.1%
- 8pm–5am15 flights—
Scale runs 50% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 59.1% on time, against 88.9% 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 5am–8am window is the busiest, with 1,429 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 23 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 63.1% on time, 23 points below November, the best at 86.2%. 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, Sunday is the strongest day at 81.5% on time and Friday the weakest at 75.5%. 6 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 74,000 reported delay minutes.
- 33%National Airspace System
- 30%Carrier
- 29%Late-arriving aircraft
- 8%Extreme weather
33% 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 24,000 minutes out of 74,000, against a national NAS share of 21%. The split is drawn from 74,271 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 88.9% on time here.
Cancellations sit at 1.33% against a national 1.81%, which is ordinary. Diversions add another 0.04%.
Connections and stage length
What a delay here actually 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 are the a little over an hour kind, which a normal layover absorbs.
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 5am–8am window matters as much as it does.
The return leg is a different operation and performs like one: it runs 75.8% on time across 5,039 flights, 3 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 3 points of difference.
The sample behind these figures is 5,038 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 86.2% on time and July 63.1%, a swing of 23 points. If the dates move at all, move them out of July before you think about anything else. 4,969 completed flights over 12 months sit behind that.
Common questions
COS to DEN questions
How often is COS to DEN delayed?
About one flight in five arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 21.2% of the 5,038 flights in this analysis, against 22.4% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on COS to DEN?
SkyWest Airlines leads at 81.3% on time across 3,282 flights. United Airlines is at the other end on 72.9%, a gap of 8 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 COS to DEN?
The 5am–8am departure window is the strongest at 88.9% on time. The 5pm–8pm window is the weakest at 59.1%, 30 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 COS to DEN?
July is the weakest month at 63.1% on time, compared with 86.2% in November. Across the year that is 23 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
- DEN to COS — the return legseparate record
- Denver International (DEN) delay statistics
- SkyWest Airlines on-time record81.3%
- Southwest Airlines on-time record75.0%
- United Airlines on-time record72.9%
- The best time of day to fly, according to 7.04 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. COS to DEN and DEN to COS 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.