Carrier route record
UAIAH→BOS
United Airlines · Houston to Boston
- Flights
- 1,549
- Period
- September 2025 to August 2026
- Share of route
- 77%
- Carriers
- 2
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with United Airlines.
United on IAH to BOS lands a B, about a point worse than the national rate of 77.3%. About one flight in four arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That rests on 1,549 flights, with a median arrival 5 minutes early.
The US average over the same twelve months is 77.3%, 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
76.1%
Arrivals under 15 minutes late, of 1,532 completed flights
Avg delay
72 min
Across delayed arrivals only, not all flights
Cancelled
1.10%
National rate is 1.89%
Whole route
71.5%
Every carrier on IAH to BOS, 2,017 flights
These figures cover 1,549 flights between September 2025 and August 2026. Beyond the headline rate, 10.3% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
United against every carrier on IAH to BOS
United flew 1,549 of the 2,017 flights on IAH to BOS, most of the route. Its 76.1% on time is 5 points better than the route as a whole, which runs 71.5%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from United at 76.1% to JetBlue at 55.9%.
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) | 1,549 | 76.1% | 72 min | 1.10% | B |
| JetBlue Airways | 468 | 55.9% | 88 min | 2.78% | D |
Flight by flight
United flight numbers on IAH to BOS
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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 30 points, against half a point between the best and worst carrier.
- 5am–8am361 flights94.1%
- 8am–11am242 flights75.6%
- 11am–2pm349 flights64.3%
- 2pm–5pm212 flights70.8%
- 5pm–8pm385 flights73.1%
- 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 94.1% 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 385 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. October was the busiest month here, with 152 flights.
Across the week, Saturday is the strongest day at 82.1% on time and Sunday the weakest at 72.4%, a spread of 10 points.
Arrival by arrival
How late United on IAH to BOS runs when it is late
United on IAH to BOS often beats the schedule: 445 of 1,532 completed flights, 29%, arrived 15 minutes or more early. The 366 late arrivals split 97 under half an hour, 111 between 30 and 60 minutes, and 158 an hour or more.
- 15+ min early445 flights29.0%
- Within 15 min721 flights47.1%
- 15–29 min late97 flights6.3%
- 30–59 min late111 flights7.2%
- 1–2 hours late89 flights5.8%
- 2+ hours late69 flights4.5%
Scale runs 0% to 100%.
Share of 1,532 completed flights by arrival against schedule.
67 of 383 late departures made up the time and arrived on time, 17% of them. 50 flights left on time and still arrived late.
The worst days
Worst days for United on IAH to BOS
The latest arrival of the period was on 13 October 2025, 6 hours 33 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 13 October 2025 | 6 hours 33 minutes | Late-arriving aircraft |
| 14 May 2026 | 6 hours 15 minutes | Late-arriving aircraft |
| 25 September 2025 | 5 hours 14 minutes | National Airspace System |
| 13 October 2025 | 5 hours 3 minutes | National Airspace System |
| 30 July 2026 | 4 hours 47 minutes | Late-arriving aircraft |
Delay causes
Why United runs late on this route
National Airspace System accounts for 52% of the 26,000 delay minutes carriers reported here, and the remaining four split what is left.
- 52%National Airspace System
- 33%Late-arriving aircraft
- 12%Carrier
- 4%Extreme weather
52% 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 14,000 minutes out of 26,000, against a national NAS share of 21%. The split is drawn from 26,401 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 94.1% on time here.
Cancellations sit at 1.10% against a national 1.89%, which is ordinary. Diversions add another 0.00%.
Connections and stage length
What a delay here costs
10.3% 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.
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 82.3% on time across 1,550 flights, 6 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 6 points of difference.
The sample behind these figures is 1,549 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. 1,532 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 BOS55.9%
- United Airlines network-wide record
- George Bush Intercontinental (IAH) delay statistics
- Boston Logan International (BOS) delay statistics
- Why the first flight of the morning is statistically safest
- How often a connection fails at the major US hubs
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.