Carrier route record
UAIAH→DCA
United Airlines · Houston to Washington
- Flights
- 2,413
- Period
- July 2025 to June 2026
- Share of route
- 75%
- Carriers
- 3
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on IAH to DCA 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 77.6%. The late ones land a little over an hour behind schedule. That rests on 2,413 flights, with a median arrival 5 minutes early.
The US average over the same twelve months is 77.6%, so there is little to separate United on IAH to DCA from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
75.2%
Arrivals under 15 minutes late, of 2,383 completed flights
Avg delay
70 min
Across delayed arrivals only, not all flights
Cancelled
0.79%
National rate is 1.81%
Whole route
74.8%
Every carrier on IAH to DCA, 3,202 flights
These figures cover 2,413 flights between July 2025 and June 2026. Beyond the headline rate, 9.4% 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
United against every carrier on IAH to DCA
United flew 2,413 of the 3,202 flights on IAH to DCA, most of the route. Its 75.2% on time is about level with the route as a whole at 74.8%. Ranked by on-time rate it is number two of three carriers on the route, where the range runs from Republic at 75.9% to PSA at 69.0%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
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 |
|---|---|---|---|---|---|
| Republic Airways | 513 | 75.9% | 64 min | 4.87% | B− |
| United Airlines (this page) | 2,413 | 75.2% | 70 min | 0.79% | B+ |
| PSA Airlinesthin sample | 276 | 69.0% | 109 min | 5.07% | C− |
Flight by flight
United flight numbers on IAH to DCA
Departure window
When United runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 27 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–8am363 flights92.8%
- 8am–11am307 flights83.6%
- 11am–2pm364 flights76.3%
- 2pm–5pm488 flights70.7%
- 5pm–8pm549 flights65.8%
- 8pm–5am342 flights68.9%
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 92.8% of the time, against 65.8% for the evening window. That is 27 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5pm–8pm window is the busiest, with 549 flights scheduled in it.
Across the year
United on IAH to DCA through the year
July is the worst month at 58.6% on time, 28 points below December, the best at 87.0%. 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. March was the busiest month here, with 209 flights.
Across the week, Tuesday is the strongest day at 83.4% on time and Friday the weakest at 70.7%. 13 points is a smaller lever than departure hour, but it is free.
Delay causes
Why United runs late on this route
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 41,000 reported delay minutes.
- 42%National Airspace System
- 30%Late-arriving aircraft
- 19%Carrier
- 10%Extreme weather
42% 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 17,000 minutes out of 41,000, against a national NAS share of 21%. The split is drawn from 41,139 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 92.8% on time here.
Cancellations are rare at 0.79%, 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 costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 9.4% 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.
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. 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 is a different operation and performs like one: it runs 83.8% on time across 2,413 flights, 9 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 9 points of difference.
The sample behind these figures is 2,413 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 United on IAH to DCA
Put together: the calendar is the biggest lever here, not the carrier or the hour. December runs 87.0% on time and July 58.6%, a swing of 28 points. If the dates move at all, move them out of July before you think about anything else. 2,383 completed flights over 12 months sit behind that.
Related
Where to go next
- IAH to DCA, every carrier
- United on DCA to IAH, the return leg
- Republic Airways on IAH to DCA75.9%
- PSA Airlines on IAH to DCA69.0%
- United Airlines network-wide record
- George Bush Intercontinental (IAH) delay statistics
- Ronald Reagan Washington National (DCA) delay statistics
- How often a connection fails at the major US hubs
- The best time of day to fly, according to 7.04 million flight records
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.