Route reliability record
DEN→DCA
Denver to Washington
- Flights
- 1,351
- Period
- July 2025 to June 2026
- Distance
- 1,476 mi
- Carriers
- 2
This route lands a B+, 4 points better than the national rate of 77.6%. About one flight in five arrives 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 1,351 DEN to DCA flights, of which United Airlines flew 365 at 88.7% on time.
Best time to fly DEN to DCA: a 5am–8am departure, ideally on a Saturday. Flights in that window arrived on time 94.6% of the time and Saturday flights 90.0%, against 81.2% for the route overall.
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
81.2%
Arrivals under 15 minutes late, of 1,335 completed flights
Avg delay
73 min
Across delayed arrivals only, not all flights
Cancelled
0.67%
National rate is 1.81%
Best carrier
United
88.7% on time across 365 flights
These figures cover 1,351 flights between July 2025 and June 2026. The median arrival is 10 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 DEN to DCA
The choice of carrier is not cosmetic here. United Airlines arrives on time 88.7% of the time; Frontier Airlines manages 78.4%. Sample sizes sit next to every figure, because a two-point gap across 986 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 365 | 88.7% | 61 min | 0.27% | A+ |
| Frontier Airlines | 986 | 78.4% | 76 min | 0.81% | B+ |
United leads Frontier by 10 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Flight by flight
Flights on DEN to DCA
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.
Best ways to make this trip
The most reliable ways to fly Denver to Washington
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. 3 of the top 5 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. DEN → DCADenver to Washington | United Airlines | 88.5% | 88.7% | 0.27% | 8am–11am, Tue | — |
| 2. DEN → IADDenver to Washington | United Airlines | 84.0% | 84.4% | 0.46% | 5am–8am, Tue | UA 1101 08:00 |
| 3. DEN → BWIDenver to Baltimore | United Airlines | 80.0% | 80.6% | 0.78% | 2pm–5pm, Wed | UA 1362 09:46 |
| 4. DEN → DCADenver to Washington | Frontier Airlines | 77.8% | 78.4% | 0.81% | 5am–8am, Sat | F9 686 07:35 |
| 5. DEN → BWIDenver to Baltimore | Southwest Airlines | 74.0% | 75.1% | 1.47% | 5am–8am, Wed | — |
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 10 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am314 flights94.6%
- 8am–11am365 flights88.7%
- 11am–2pm316 flights76.9%
- 2pm–5pm356 flights65.5%
- 5pm–8pm—
- 8pm–5am—
Scale runs 55% to 100%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 94.6% of the time, against 65.5% for the afternoon window. That is 29 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8am–11am window is the busiest, with 365 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 14 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 74.1% on time, 14 points below October, the best at 87.8%. 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 90.0% on time and Thursday the weakest at 77.1%. 13 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
One category carries most of the weight here. National Airspace System accounts for 46% of the 18,000 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 46%National Airspace System
- 27%Late-arriving aircraft
- 25%Carrier
- 3%Extreme weather
46% 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 8,454 minutes out of 18,000, against a national NAS share of 21%. The split is drawn from 18,367 reported delay minutes.
Cancellations are rare at 0.67%, below the national 1.81% 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
7.5% 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 last a little over an hour, 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. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
The return leg runs 78.5% on time across 1,349 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 1,351 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 DCA 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 87.8% on time and July 74.1%, a swing of 14 points. If the dates move at all, move them out of July before you think about anything else. 1,335 completed flights over 12 months sit behind that.
Common questions
DEN to DCA questions
How often is DEN to DCA delayed?
About 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 18.8% of the 1,351 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 DEN to DCA?
United Airlines leads at 88.7% on time across 365 flights. Frontier Airlines is at the other end on 78.4%, a gap of 10 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 DCA?
The 5am–8am departure window is the strongest at 94.6% on time. The 2pm–5pm window is the weakest at 65.5%, 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 July delays on DEN to DCA?
July is the weakest month at 74.1% on time, compared with 87.8% in October. Across the year that is 14 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
- DCA to DEN — the return legseparate record
- Denver International (DEN) delay statistics
- Ronald Reagan Washington National (DCA) delay statistics
- United Airlines on DEN to DCA88.7%
- Frontier Airlines on DEN to DCA78.4%
- DEN to PHX, a related route75.7%
- BOS to DCA, a related route74.0%
- DEN to SLC, a related route77.5%
- United Airlines on-time record88.7%
- Frontier Airlines on-time record78.4%
- Same route, different airline: where the carrier you pick matters most
- The best time of day to fly, according to 7.04 million flight records
Direction matters. DEN to DCA and DCA to DEN 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.