Carrier route record
UAIAH→BWI
United Airlines · Houston to Baltimore
- Flights
- 831
- Period
- September 2025 to August 2026
- Share of route
- 64%
- Carriers
- 4
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with United Airlines.
United on IAH to BWI lands a B+, 4 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 about an hour on average. That rests on 831 flights, with a median arrival 5 minutes early.
Set against the rest of the country, United's IAH to BWI record is 4 points better than the US average of 77.3%. That gap is worth roughly 40 fewer late arrivals for every thousand flights.
Key figures
On time
81.3%
Arrivals under 15 minutes late, of 825 completed flights
Avg delay
60 min
Across delayed arrivals only, not all flights
Cancelled
0.60%
National rate is 1.89%
Whole route
77.3%
Every carrier on IAH to BWI, 1,308 flights
These figures cover 831 flights between September 2025 and August 2026. The median arrival is 5 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.
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Carrier by carrier
United against every carrier on IAH to BWI
United flew 831 of the 1,308 flights on IAH to BWI, most of the route. Its 81.3% on time is 4 points better than the route as a whole, which runs 77.3%. 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 52.1%. Three 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) | 831 | 81.3% | 60 min | 0.60% | B+ |
| Spirit Airlinesthin sample | 295 | 79.9% | 59 min | 2.03% | B |
| Frontier Airlinesthin sample | 180 | 52.1% | 73 min | 7.78% | F− |
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
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.
- 5am–8am178 flights90.4%
- 8am–11am—
- 11am–2pm357 flights86.2%
- 2pm–5pm2 flights—
- 5pm–8pm275 flights70.2%
- 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 90.4% of the time, against 70.2% 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
Delays peak in March, when the on-time rate falls to 72.6%. January is the strongest month at 90.8%. Moving a flexible trip across that boundary buys 18 points. April was the busiest month here, with 82 flights.
Across the week, Tuesday is the strongest day at 87.8% on time and Sunday the weakest at 75.0%, a spread of 13 points.
Arrival by arrival
How late United on IAH to BWI runs when it is late
The 154 late arrivals split 59 under half an hour, 49 between 30 and 60 minutes, and 46 an hour or more.
- 15+ min early161 flights19.5%
- Within 15 min510 flights61.8%
- 15–29 min late59 flights7.2%
- 30–59 min late49 flights5.9%
- 1–2 hours late29 flights3.5%
- 2+ hours late17 flights2.1%
Scale runs 0% to 100%.
Share of 825 completed flights by arrival against schedule.
30 of 139 late departures made up the time and arrived on time, 22% of them. In the other direction, 45 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at BWI.
The worst days
Worst days for United on IAH to BWI
The latest arrival of the period was on 21 July 2026, 9 hours 14 minutes behind schedule; most of its delay minutes were filed as national airspace system delay. Three of the five worst days fell in July 2026.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 21 July 2026 | 9 hours 14 minutes | National Airspace System |
| 27 August 2026 | 5 hours 46 minutes | Carrier |
| 9 July 2026 | 4 hours 38 minutes | Late-arriving aircraft |
| 22 July 2026 | 4 hours 22 minutes | Carrier |
| 15 March 2026 | 4 hours 6 minutes | Carrier |
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 9,308 reported delay minutes.
- 35%Late-arriving aircraft
- 35%Carrier
- 25%National Airspace System
- 5%Extreme weather
35% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 9,308 reported delay minutes here, that single category outweighs weather by 7 to one. The split is drawn from 9,308 reported delay minutes.
The largest share of delay minutes, 35%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 3,270 of the 9,308 delay minutes reported here.
Cancellations are rare at 0.60%, below the national 1.89% 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
5.6% 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 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.
The return leg runs 84.0% on time across 833 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.
One caution: this is a thin sample. 831 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. 831 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 81.3% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 825 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 BWI79.9%
- Frontier Airlines on IAH to BWI52.1%
- 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 7.05 million flight records
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.