Route reliability record
DEN→ASE
Denver to Aspen
- Flights
- 2,715
- Period
- July 2025 to June 2026
- Distance
- 125 mi
- Carriers
- 1
This route carries a cancellation problem, not just a delay problem: 5.2% of scheduled flights never operate, against 1.8% nationally. Of the ones that do fly, close to three flights in four arrive on time, worth a C− overall. The punctuality figure counts only flights that actually departed, so it flatters an operation that cancels this often. That rests on 2,715 flights, with a median arrival 6 minutes early.
The US average over the same twelve months is 77.6%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
74.8%
Arrivals under 15 minutes late, of 2,536 completed flights
Avg delay
96 min
Across delayed arrivals only, not all flights
Cancelled
5.23%
National rate is 1.81%
Best carrier
SkyWest
74.8% on time across 2,715 flights
These figures cover 2,715 flights between July 2025 and June 2026. Beyond the headline rate, 11.4% 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 ASE
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.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlines | 2,715 | 74.8% | 96 min | 5.23% | C− |
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 half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am113 flights91.0%
- 8am–11am467 flights80.0%
- 11am–2pm734 flights72.2%
- 2pm–5pm443 flights75.9%
- 5pm–8pm670 flights69.6%
- 8pm–5am288 flights76.5%
Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 91.0% of the time, against 69.6% for the evening window. That is 21 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 734 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 59.9% on time, 28 points below November, the best at 87.6%. 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 310 flights.
Across the week, Wednesday is the strongest day at 80.8% on time and Sunday the weakest at 71.4%. 9 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 62,000 reported delay minutes.
- 34%National Airspace System
- 24%Late-arriving aircraft
- 22%Carrier
- 20%Extreme weather
Extreme weather accounts for 20% of delay minutes, well above the single-digit share typical across the system. Weather delays are lumpy: they arrive as whole bad days rather than as a steady drag, so the monthly strip above is the more useful view of the risk. The national share is 6%, so this operation carries roughly 3.2 times the usual weather exposure. The split is drawn from 61,667 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 21,000 minutes out of 62,000, against a national NAS share of 21%.
Cancellations run at 5.23%, against 1.81% nationally. That is about one flight in twenty cancelled outright. A cancelled flight is invisible in every on-time figure on this page, so the punctuality numbers above describe only the flights that actually operated.
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. 11.4% 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 125 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 75.2% on time across 2,716 flights, within half a point 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 2,715 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 delay figures matter less here than the 5.23% cancellation rate. A late arrival costs you an hour and a half; a cancelled flight costs you the day. Book the 5am–8am departure so there is still a schedule behind you if it goes wrong, and treat a same-day connection as optimistic. 2,536 completed flights over 12 months sit behind that.
Common questions
DEN to ASE questions
How often is DEN to ASE 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 25.2% of the 2,715 flights in this analysis, against 22.4% nationally. Delayed flights are late by an hour and a half on average.
How reliable is DEN to ASE compared with the rest of the country?
74.8% of flights arrive on time here against a national 77.6%, a difference of 3 points against it. That is worth a C− on this site's grading scale.
What time of day has the fewest delays on DEN to ASE?
The 5am–8am departure window is the strongest at 91.0% on time. The 5pm–8pm window is the weakest at 69.6%, 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 ASE?
July is the weakest month at 59.9% on time, compared with 87.6% 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
- ASE to DEN — the return legseparate record
- Denver International (DEN) delay statistics
- SkyWest Airlines on-time record74.8%
- What a cancellation rate actually tells you (and what it hides)
- The best time of day to fly, according to 7.04 million flight records
Direction matters. DEN to ASE and ASE 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.