Route reliability record
DCA→DEN
Washington to Denver
- Flights
- 1,347
- Period
- September 2025 to August 2026
- Distance
- 1,476 mi
- Carriers
- 2
This route lands a B+, about a point better than the national rate of 77.3%. Roughly one flight in five arrives 15 minutes late or worse, and those flights are late by an hour and a half on average. That rests on 1,347 DCA to DEN flights, with a median arrival 7 minutes early.
Best time to fly DCA to DEN: a 11am–2pm departure, ideally on a Saturday. Flights in that window arrived on time 95.5% of the time and Saturday flights 87.6%, against 78.2% for the route overall.
The US average over the same twelve months is 77.3%, 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
78.2%
Arrivals under 15 minutes late, of 1,326 completed flights
Avg delay
82 min
Across delayed arrivals only, not all flights
Cancelled
0.89%
National rate is 1.89%
Best carrier
Frontier
78.1% on time across 983 flights
These figures cover 1,347 flights between September 2025 and August 2026. The median arrival is 7 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.
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Carrier by carrier
Which airline is most reliable on DCA to DEN
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 |
|---|---|---|---|---|---|
| United Airlinesthin sample | 364 | 78.4% | 87 min | 0.55% | B+ |
| Frontier Airlines | 983 | 78.1% | 81 min | 1.02% | B |
Flight by flight
Flights on DCA to DEN
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
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Best ways to make this trip
The most reliable ways to fly Washington to Denver
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 4 of the top 5 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. BWI → DENBaltimore to Denver | United Airlines | 84.1% | 84.5% | 0.48% | 8am–11am, Tue | UA 2412 08:30 |
| 2. IAD → DENWashington to Denver | United Airlines | 83.7% | 84.1% | 0.50% | 5am–8am, Tue | UA 1587 12:48 |
| 3. IAD → DENWashington to Denver | Southwest Airlines | 77.6% | 78.4% | 1.01% | 5am–8am, Sat | — |
| 4. DCA → DENWashington to Denver | Frontier Airlines | 77.3% | 78.1% | 1.02% | 11am–2pm, Sat | F9 685 07:00 |
| 5. BWI → DENBaltimore to Denver | Southwest Airlines | 70.9% | 72.2% | 1.82% | 5am–8am, Tue | — |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
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 29 points, against half a point between the best and worst carrier.
- 5am–8am189 flights85.6%
- 8am–11am170 flights85.7%
- 11am–2pm66 flights95.5%
- 2pm–5pm616 flights77.7%
- 5pm–8pm306 flights66.7%
- 8pm–5am—
Scale runs 60% to 100%. Rows with fewer than 30 flights show a dash.
The best window here is not the first bank but the 11am–2pm slot at 95.5% on time, ahead of 5pm–8pm at 66.7%. Where the curve peaks mid-day rather than at dawn, the constraint is usually congestion at one end rather than the aircraft's own rotation. The 2pm–5pm window is the busiest, with 616 flights scheduled in it.
Explore
Filter DCA to DEN by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On DCA to DEN, the best departure window is 11am–2pm at 95.5% on time and the worst is 5pm–8pm at 66.7%, a wide gap of 28.8 points. All US flights leaving 11am–2pm ran 78.3%.
- 5–8am85.6%
- 8–11am85.7%
- 11am–2pm95.5%
- 2–5pm77.7%
- 5–8pm66.7%
- 8pm–5am—
best all US flightsScale 60% to 100%. Cells under 30 flights show a dash.
Across the year
When delays peak on this route
This route's year swings by 20 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.
August is the worst month at 67.6% on time, 20 points below October, the best at 87.7%. 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. January was the busiest month here, with 116 flights.
Across the week, Saturday is the strongest day at 87.6% on time and Friday the weakest at 73.3%, a spread of 14 points.
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 24,000 reported delay minutes.
- 41%National Airspace System
- 27%Late-arriving aircraft
- 24%Carrier
- 8%Extreme weather
41% 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 9,828 minutes out of 24,000, against a national NAS share of 21%. The split is drawn from 23,757 reported delay minutes.
Cancellations are rare at 0.89%, below the national 1.89% 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 actually costs
7.7% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last an hour and a half, which a normal layover absorbs.
The 1,476 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty.
The return leg runs 80.6% on time across 1,347 flights, within 2 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 1,347 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.
Work out the risk of missing a connection in DEN after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. October runs 87.7% on time and August 67.6%, a swing of 20 points. If the dates move at all, move them out of August before you think about anything else. 1,326 completed flights over 12 months sit behind that.
Common questions
DCA to DEN questions
How often is DCA to DEN delayed?
Roughly one flight in five arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 21.8% of the 1,347 flights in this analysis, against 22.7% nationally. Delayed flights are late by an hour and a half on average.
How reliable is DCA to DEN compared with the rest of the country?
78.2% of flights arrive on time here against a national 77.3%, a difference of about a point in its favour. That is worth a B+ on this site's grading scale.
What time of day has the fewest delays on DCA to DEN?
The 11am–2pm departure window is the strongest at 95.5% on time. The 5pm–8pm window is the weakest at 66.7%, 29 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 August delays on DCA to DEN?
August is the weakest month at 67.6% on time, compared with 87.7% in October. Across the year that is 20 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 DCA — the return legseparate record
- Ronald Reagan Washington National (DCA) delay statistics
- Denver International (DEN) delay statistics
- United Airlines on DCA to DEN78.4%
- Frontier Airlines on DCA to DEN78.1%
- DCA to BOS, a related route70.1%
- PHX to DEN, a related route76.7%
- DCA to ORD, a related route73.8%
- United Airlines on-time record78.4%
- Frontier Airlines on-time record78.1%
- 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. DCA to DEN and DEN to DCA are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.