Route reliability record
DCA→IAH
Washington to Houston
- Flights
- 3,333
- Period
- September 2025 to August 2026
- Distance
- 1,208 mi
- Carriers
- 3
This route lands a B, 3 points better than the national rate of 77.3%. 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 rests on 3,333 DCA to IAH flights, of which United Airlines flew 2,384 at 83.5% on time.
Best time to fly DCA to IAH: a 5am–8am departure, ideally on a Saturday. Flights in that window arrived on time 89.8% of the time and Saturday flights 85.5%, against 80.3% for the route overall.
United Airlines is the most reliable of the three carriers covered here at 83.5% on time across 2,384 flights.
Key figures
On time
80.3%
Arrivals under 15 minutes late, of 3,241 completed flights
Avg delay
79 min
Across delayed arrivals only, not all flights
Cancelled
2.31%
National rate is 1.89%
Best carrier
United
83.5% on time across 2,384 flights
These figures cover 3,333 flights between September 2025 and August 2026. Beyond the headline rate, 8.6% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
Which airline is most reliable on DCA to IAH
The choice of carrier is not cosmetic here. United Airlines arrives on time 83.5% of the time; PSA Airlines manages 66.6%. Sample sizes sit next to every figure, because a two-point gap across 438 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 2,384 | 83.5% | 85 min | 0.80% | B+ |
| Republic Airways | 511 | 75.7% | 56 min | 5.09% | B− |
| PSA Airlines | 438 | 66.6% | 83 min | 7.31% | C− |
PSA Airlines cancels 7.3% of what it schedules here, the highest in the table. A cancelled flight never appears in an on-time rate, so read that column alongside the punctuality one rather than after it.
Flight by flight
Flights on DCA to IAH
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 Houston
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. IAD → IAHWashington to Houston | United Airlines | 84.3% | 84.7% | 0.48% | 5am–8am, Tue | UA 1524 08:30 |
| 2. BWI → IAHBaltimore to Houston | United Airlines | 83.0% | 84.0% | 1.20% | 5am–8am, Thu | — |
| 3. DCA → IAHWashington to Houston | United Airlines | 82.8% | 83.5% | 0.80% | 5am–8am, Wed | UA 1450 06:00 |
| 4. BWI → HOUBaltimore to Houston | Southwest Airlines | 74.6% | 75.7% | 1.43% | 5am–8am, Wed | — |
| 5. DCA → HOUWashington to Houston | Southwest Airlines | 73.8% | 75.4% | 2.18% | 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 31 points, against 17 points between the best and worst carrier.
- 5am–8am585 flights89.8%
- 8am–11am416 flights88.0%
- 11am–2pm791 flights86.6%
- 2pm–5pm834 flights71.4%
- 5pm–8pm170 flights58.4%
- 8pm–5am537 flights75.0%
Scale runs 50% to 95%.
The 5pm–8pm window is where this operation falls apart: 58.4% on time, against 89.8% 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 2pm–5pm window is the busiest, with 834 flights scheduled in it.
Explore
Filter DCA to IAH 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 IAH, the best departure window is 5am–8am at 89.8% on time and the worst is 5pm–8pm at 58.4%, a wide gap of 31.4 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am89.8%
- 8–11am88.0%
- 11am–2pm86.6%
- 2–5pm71.4%
- 5–8pm58.4%
- 8pm–5am75.0%
best all US flightsScale 50% to 95%.
Across the year
When delays peak on this route
This route's year swings by 19 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 70.8% on time, 19 points below February, the best at 89.7%. 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. October was the busiest month here, with 291 flights.
Across the week, Saturday is the strongest day at 85.5% on time and Sunday the weakest at 77.2%, a spread of 8 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 45% of the 51,000 delay minutes carriers reported here, and the remaining four split what is left.
- 45%Late-arriving aircraft
- 26%National Airspace System
- 22%Carrier
- 7%Extreme weather
- 0%Security
45% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 51,000 reported delay minutes here, that single category outweighs weather by 7 to one. The split is drawn from 50,674 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 89.8% on time here.
Cancellations sit at 2.31% against a national 1.89%, which is ordinary. Diversions add another 0.45%.
Connections and stage length
What a delay here actually costs
8.6% 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 a little over an hour, which a normal layover absorbs.
The 1,208 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 is a different operation and performs like one: it runs 75.3% on time across 3,337 flights, 5 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 5 points of difference.
The sample behind these figures is 3,333 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 IAH 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. February runs 89.7% on time and July 70.8%, a swing of 19 points. If the dates move at all, move them out of July before you think about anything else. 3,241 completed flights over 12 months sit behind that.
Common questions
DCA to IAH questions
How often is DCA to IAH 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 19.7% of the 3,333 flights in this analysis, against 22.7% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on DCA to IAH?
United Airlines leads at 83.5% on time across 2,384 flights. PSA Airlines is at the other end on 66.6%, a gap of 17 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 DCA to IAH?
The 5am–8am departure window is the strongest at 89.8% on time. The 5pm–8pm window is the weakest at 58.4%, 31 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 DCA to IAH?
July is the weakest month at 70.8% on time, compared with 89.7% in February. Across the year that is 19 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
- IAH to DCA — the return legseparate record
- Ronald Reagan Washington National (DCA) delay statistics
- George Bush Intercontinental (IAH) delay statistics
- United Airlines on DCA to IAH83.5%
- Republic Airways on DCA to IAH75.7%
- PSA Airlines on DCA to IAH66.6%
- DCA to BOS, a related route70.1%
- ORD to IAH, a related route76.0%
- DCA to ORD, a related route73.8%
- United Airlines on-time record83.5%
- Republic Airways on-time record75.7%
- PSA Airlines on-time record66.6%
- Same route, different airline: where the carrier you pick matters most
- Why the first flight of the morning is statistically safest
Direction matters. DCA to IAH and IAH 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.