Route reliability record
COS→DEN
Colorado Springs to Denver
- Flights
- 5,059
- Period
- June 2025 to May 2026
- Distance
- 73 mi
- Carriers
- 3
This route lands a B, level with the national rate of 77.4%. Roughly one flight in four 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 5,059 flights, of which SkyWest Airlines flew 3,259 at 79.6% on time.
SkyWest Airlines is the most reliable of the three carriers covered here at 79.6% on time across 3,259 flights.
Key figures
On time
77.4%
Arrivals under 15 minutes late, of 4,983 completed flights
Avg delay
72 min
Across delayed arrivals only, not all flights
Cancelled
1.48%
National rate is 1.80%
Best carrier
SkyWest
79.6% on time across 3,259 flights
These figures cover 5,059 flights between June 2025 and May 2026. Beyond the headline rate, 8.5% 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 COS to DEN
The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 79.6% of the time; United Airlines manages 70.6%. Sample sizes sit next to every figure, because a two-point gap across 645 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlines | 3,259 | 79.6% | 75 min | 1.84% | B |
| Southwest Airlines | 1,155 | 74.9% | 57 min | 0.52% | C+ |
| United Airlines | 645 | 70.6% | 82 min | 1.40% | C |
SkyWest leads United by 9 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 9 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am1,405 flights87.6%
- 8am–11am1,089 flights82.9%
- 11am–2pm1,001 flights80.1%
- 2pm–5pm721 flights67.3%
- 5pm–8pm828 flights57.7%
- 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: 57.7% on time, against 87.6% 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.
Across the year
When delays peak on this route
This route's year swings by 24 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.
June is the worst month at 62.6% on time, 24 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.
Across the week, Saturday is the strongest day at 80.0% on time and Friday the weakest at 73.4%. 7 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.
- 35%National Airspace System
- 30%Carrier
- 28%Late-arriving aircraft
- 8%Extreme weather
35% 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 28,000 minutes out of 81,000, against a national NAS share of 21%.
Cancellations sit at 1.48% against a national 1.80%, which is ordinary. Diversions add another 0.02%.
Connections and stage length
What a delay here actually costs
8.5% of arrivals land an hour or more late, close to the national 8.2%. 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 runs 74.9% on time across 5,059 flights, within 3 points 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 5,059 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 June 62.6%, a swing of 24 points. If the dates move at all, move them out of June before you think about anything else.
Common questions
COS to DEN questions
How often is COS to DEN delayed?
Roughly 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 22.6% of the 5,059 flights in this analysis, against 22.6% 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 79.6% on time across 3,259 flights. United Airlines is at the other end on 70.6%, a gap of 9 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 87.6% on time. The 5pm–8pm window is the weakest at 57.7%, 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 June delays on COS to DEN?
June is the weakest month at 62.6% on time, compared with 86.2% in November. Across the year that is 24 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 record79.6%
- Southwest Airlines on-time record74.9%
- United Airlines on-time record70.6%
- The best time of day to fly, according to 7.05 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, June 2025 to May 2026. Updated monthly. How this data is collected.