Carrier route record
UAIAH→BOS
United Airlines · Houston to Boston
- Flights
- 1,565
- Period
- July 2025 to June 2026
- Share of route
- 77%
- Carriers
- 2
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on IAH to BOS 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 1,565 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 BOS from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
75.9%
Arrivals under 15 minutes late, of 1,548 completed flights
Avg delay
73 min
Across delayed arrivals only, not all flights
Cancelled
1.09%
National rate is 1.81%
Whole route
72.6%
Every carrier on IAH to BOS, 2,025 flights
These figures cover 1,565 flights between July 2025 and June 2026. Beyond the headline rate, 9.6% 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 BOS
United flew 1,565 of the 2,025 flights on IAH to BOS, most of the route. Its 75.9% on time is 3 points better than the route as a whole, which runs 72.6%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from United at 75.9% to JetBlue at 61.4%.
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 |
|---|---|---|---|---|---|
| United Airlines (this page) | 1,565 | 75.9% | 73 min | 1.09% | B |
| JetBlue Airways | 460 | 61.4% | 73 min | 1.74% | D |
Flight by flight
United flight numbers on IAH to BOS
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 31 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–8am362 flights95.0%
- 8am–11am242 flights76.0%
- 11am–2pm349 flights64.3%
- 2pm–5pm173 flights72.9%
- 5pm–8pm439 flights70.4%
- 8pm–5am—
Scale runs 55% to 100%. Rows with fewer than 30 flights show a dash.
The weak window here is the middle of the day, not the evening: 11am–2pm runs 64.3% on time against 95.0% for 5am–8am. That shape usually means a departure bank rather than an accumulating delay, so the recovery later in the afternoon is real rather than noise. The 5pm–8pm window is the busiest, with 439 flights scheduled in it.
Across the year
United on IAH to BOS through the year
Delays peak in October, when the on-time rate falls to 59.2%. February is the strongest month at 94.4%. Moving a flexible trip across that boundary buys 35 points. July was the busiest month here, with 154 flights.
Across the week, Saturday is the strongest day at 81.9% on time and Thursday the weakest at 71.3%. 11 points is a smaller lever than departure hour, but it is free.
Delay causes
Why United runs late on this route
One category carries most of the weight here. National Airspace System accounts for 49% of the 27,000 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 49%National Airspace System
- 30%Late-arriving aircraft
- 15%Carrier
- 7%Extreme weather
49% 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 13,000 minutes out of 27,000, against a national NAS share of 21%. The split is drawn from 27,063 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 95.0% on time here.
Cancellations sit at 1.09% against a national 1.81%, which is ordinary. Diversions add another 0.00%.
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. 9.6% 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.
At 1,597 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The return leg is a different operation and performs like one: it runs 83.8% on time across 1,567 flights, 8 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 8 points of difference.
The sample behind these figures is 1,565 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 BOS
Put together: the calendar is the biggest lever here, not the carrier or the hour. February runs 94.4% on time and October 59.2%, a swing of 35 points. If the dates move at all, move them out of October before you think about anything else. 1,548 completed flights over 12 months sit behind that.
Related
Where to go next
- IAH to BOS, every carrier
- United on BOS to IAH, the return leg
- JetBlue Airways on IAH to BOS61.4%
- United Airlines network-wide record
- George Bush Intercontinental (IAH) delay statistics
- Boston Logan International (BOS) 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.