Carrier route record
UAIAH→BWI
United Airlines · Houston to Baltimore
- Flights
- 814
- Period
- July 2025 to June 2026
- Share of route
- 62%
- Carriers
- 4
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on IAH to BWI lands a B+, level with the national rate of 77.6%. Roughly one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 814 flights, with a median arrival 4 minutes early.
The US average over the same twelve months is 77.6%, so there is little to separate United on IAH to BWI from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
77.9%
Arrivals under 15 minutes late, of 807 completed flights
Avg delay
62 min
Across delayed arrivals only, not all flights
Cancelled
0.61%
National rate is 1.81%
Whole route
75.8%
Every carrier on IAH to BWI, 1,311 flights
These figures cover 814 flights between July 2025 and June 2026. The median arrival is 4 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
United against every carrier on IAH to BWI
United flew 814 of the 1,311 flights on IAH to BWI, most of the route. Its 77.9% on time is 2 points better than the route as a whole, which runs 75.8%. Ranked by on-time rate it is number two of four carriers on the route, where the range runs from SkyWest at 100.0% to Frontier at 55.9%. Two 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 |
|---|---|---|---|---|---|
| SkyWest Airlinesthin sample | 2 | 100.0% | — | 0.00% | A+ |
| United Airlines (this page) | 814 | 77.9% | 62 min | 0.61% | B+ |
| Spirit Airlines | 377 | 77.0% | 59 min | 2.12% | B |
| Frontier Airlinesthin sample | 118 | 55.9% | 74 min | 5.08% | D− |
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 20 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–8am128 flights88.2%
- 8am–11am—
- 11am–2pm357 flights82.8%
- 2pm–5pm—
- 5pm–8pm310 flights68.7%
- 8pm–5am19 flights—
Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 88.2% of the time, against 68.7% for the evening window. That is 20 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 11am–2pm window is the busiest, with 357 flights scheduled in it.
Across the year
United on IAH to BWI through the year
July is the worst month at 48.3% on time, 43 points below January, the best at 90.8%. 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. April was the busiest month here, with 82 flights.
Across the week, Tuesday is the strongest day at 86.2% on time and Sunday the weakest at 70.2%. 16 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 11,000 reported delay minutes.
- 38%Late-arriving aircraft
- 34%Carrier
- 19%National Airspace System
- 10%Extreme weather
38% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 11,000 reported delay minutes here, that single category outweighs weather by 4 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 10,970 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 88.2% on time here.
Cancellations are rare at 0.61%, 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
7.4% 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 about an hour, which a normal layover absorbs.
The 1,235 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 83.2% on time across 816 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.
One caution: this is a thin sample. 814 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.
What to do with this
Booking United on IAH to BWI
Put together: treat all of this as provisional. 814 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 77.9% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 807 completed flights over 12 months sit behind that.
Related
Where to go next
- IAH to BWI, every carrier
- United on BWI to IAH, the return leg
- Spirit Airlines on IAH to BWI77.0%
- Frontier Airlines on IAH to BWI55.9%
- United Airlines network-wide record
- George Bush Intercontinental (IAH) delay statistics
- Baltimore/Washington International Thurgood Marshall (BWI) delay statistics
- Why the first flight of the morning is statistically safest
- 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.