Route reliability record
IAH→DCA
Houston to Washington
- Flights
- 3,337
- Period
- September 2025 to August 2026
- Distance
- 1,208 mi
- Carriers
- 3
This route sits in the middle of the pack with a B. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.3%. The late ones land a little over an hour behind schedule. That rests on 3,337 IAH to DCA flights, of which United Airlines flew 2,385 at 76.7% on time.
Best time to fly IAH to DCA: a 5am–8am departure, ideally on a Saturday. Flights in that window arrived on time 90.6% of the time and Saturday flights 81.0%, against 75.3% for the route overall.
United Airlines is the most reliable of the three carriers covered here at 76.7% on time across 2,385 flights.
Key figures
On time
75.3%
Arrivals under 15 minutes late, of 3,240 completed flights
Avg delay
75 min
Across delayed arrivals only, not all flights
Cancelled
2.31%
National rate is 1.89%
Best carrier
United
76.7% on time across 2,385 flights
These figures cover 3,337 flights between September 2025 and August 2026. Beyond the headline rate, 9.5% 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 IAH to DCA
The choice of carrier is not cosmetic here. United Airlines arrives on time 76.7% of the time; PSA Airlines manages 66.3%. Sample sizes sit next to every figure, because a two-point gap across 439 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 2,385 | 76.7% | 69 min | 0.67% | B+ |
| Republic Airways | 513 | 75.9% | 64 min | 4.87% | B− |
| PSA Airlines | 439 | 66.3% | 109 min | 8.20% | C− |
PSA Airlines cancels 8.2% 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 IAH 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.
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Best ways to make this trip
The most reliable ways to fly Houston 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. IAH → IADHouston to Washington | United Airlines | 82.0% | 82.4% | 0.43% | 5am–8am, Mon | UA 1549 07:20 |
| 2. IAH → BWIHouston to Baltimore | United Airlines | 80.8% | 81.3% | 0.60% | 5am–8am, Tue | — |
| 3. IAH → DCAHouston to Washington | United Airlines | 76.2% | 76.7% | 0.67% | 5am–8am, Tue | UA 654 12:00 |
| 4. HOU → BWIHouston to Baltimore | Southwest Airlines | 73.9% | 74.9% | 1.35% | 5am–8am, Wed | — |
| 5. IAH → DCAHouston to Washington | Republic Airways | 72.2% | 75.9% | 4.87% | 5am–8am, Sat | — |
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 26 points, against 10 points between the best and worst carrier.
- 5am–8am706 flights90.6%
- 8am–11am550 flights78.5%
- 11am–2pm405 flights77.8%
- 2pm–5pm500 flights70.1%
- 5pm–8pm839 flights64.3%
- 8pm–5am337 flights70.3%
Scale runs 55% to 95%.
The 5pm–8pm window is where this operation falls apart: 64.3% on time, against 90.6% 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. The 5pm–8pm window is the busiest, with 839 flights scheduled in it.
Explore
Filter IAH to DCA 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 IAH to DCA, the best departure window is 5am–8am at 90.6% on time and the worst is 5pm–8pm at 64.3%, a wide gap of 26.3 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am90.6%
- 8–11am78.5%
- 11am–2pm77.8%
- 2–5pm70.1%
- 5–8pm64.3%
- 8pm–5am70.3%
best all US flightsScale 55% to 95%.
Across the year
When delays peak on this route
This route's year swings by 21 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 63.2% on time, 21 points below January, the best at 84.0%. 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 81.0% on time and Friday the weakest at 71.2%, a spread of 10 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 60,000 reported delay minutes.
- 39%National Airspace System
- 31%Late-arriving aircraft
- 19%Carrier
- 11%Extreme weather
- 0%Security
Extreme weather accounts for 11% 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 1.9 times the usual weather exposure. The split is drawn from 60,069 reported delay minutes.
39% 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 23,000 minutes out of 60,000, against a national NAS share of 21%.
Cancellations sit at 2.31% against a national 1.89%, which is ordinary. Diversions add another 0.60%.
Connections and stage length
What a delay here actually costs
9.5% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection here, and two hours if the onward flight is on a separate ticket.
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 80.3% on time across 3,333 flights, 5 points above 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 3,337 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. January runs 84.0% on time and June 63.2%, a swing of 21 points. If the dates move at all, move them out of June before you think about anything else. 3,240 completed flights over 12 months sit behind that.
Common questions
IAH to DCA questions
How often is IAH to DCA delayed?
About one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 24.7% of the 3,337 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 IAH to DCA?
United Airlines leads at 76.7% on time across 2,385 flights. PSA Airlines is at the other end on 66.3%, 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 IAH to DCA?
The 5am–8am departure window is the strongest at 90.6% on time. The 5pm–8pm window is the weakest at 64.3%, 26 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 IAH to DCA?
June is the weakest month at 63.2% on time, compared with 84.0% in January. Across the year that is 21 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 IAH — the return legseparate record
- George Bush Intercontinental (IAH) delay statistics
- Ronald Reagan Washington National (DCA) delay statistics
- United Airlines on IAH to DCA76.7%
- Republic Airways on IAH to DCA75.9%
- PSA Airlines on IAH to DCA66.3%
- IAH to ORD, a related route75.1%
- BOS to DCA, a related route72.6%
- IAH to DFW, a related route76.4%
- United Airlines on-time record76.7%
- Republic Airways on-time record75.9%
- PSA Airlines on-time record66.3%
- Same route, different airline: where the carrier you pick matters most
- How often a connection fails at the major US hubs
Direction matters. IAH to DCA and DCA to IAH 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.