Route profile
IAD→IAH
Flight reliability, delays and best times to fly from Washington to Houston, 1,190 miles.
Right now
Aviation weather is not currently a factor.
Aviation weather is not currently a factor.
Route reliability
July 2023 – July 2026
Better than 70% of comparable major US routes (4,598 compared)
Calculated from 5,508 flights. How this is calculated
IAD → IAH arrives on time 81.0% of the time; the return trip, IAH → IAD, arrives on time 77.6% of the time, a 3.4-point gap between the two directions of the same city pair.
IAD → IAH spends 31.3 minutes on the ground on a 1,190-mile trip: 20.8 minutes from pushback to wheels-up at IAD and 10.5 minutes from touchdown to gate at IAH.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
What stands out
Every day of the week performs about the same on this route, steadier than 94% of 4,467 comparable routes.
83.2% on time on the best day (Tuesday) against 78.9% on the worst (Saturday).
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026 · Ranked against every other route with the same kind of figure and at least 4,467 in the comparison.
What sets this route apart
Where IAD to IAH differs most from similar routes by hour, weekday, month and airline, July 2023 – July 2026.
IAD to IAH is at its best against routes of similar length for flights scheduled at 10 PM: 76.7% arrive on time, 14.4 points ahead of the 62.3% those routes manage at that hour. Against all other routes the gap is 5.1 points.
IAD to IAH holds up on Sundays better than routes of similar length do: 82.3% on time to their 73.4%, a 8.9 points lead. Against all other routes the gap is 7.5 points.
March is kinder to IAD to IAH than to routes of similar length: 86.8% on time against 75.6%, 11.2 points better. Against all other routes the gap is 8.9 points.
IAD to IAH against comparable routes
July 2023 – July 2026| Measure | This route | Compared with | Them | Gap | Flights behind it |
|---|---|---|---|---|---|
| Hour: 10 PM departures | 76.7% | routes of similar length | 62.3% | +14.4 pts | 776 here, 17,976 there |
| Weekday: Sunday | 82.3% | routes of similar length | 73.4% | +8.9 pts | 776 here, 298,019 there |
| Month: March | 86.8% | routes of similar length | 75.6% | +11.2 pts | 418 here, 180,568 there |
Each comparison pools the flights of other routes, with this route’s own left out. Similar length means within 15% of this route’s 1,190 miles, with at least 5 such routes. A bucket is set against the most comparable group that has enough flights: similar length, then the same origin (at least 3 routes), then all other routes. Hours, weekdays and months appear only where both sides have 120 completed flights, and airlines where both have 600. The gap must be at least 2 points and 2 standard errors, and only the largest gap each way is kept per measure. These are differences in the flights counted, not causes.
When it goes wrong
July 2023 – July 2026
34 min late
against a median of 7 min early
Percentiles over 5,508 operations; cancelled and diverted flights are counted separately.
Will your connection be tight enough?
Layovers at IAH after arriving from IAD.
| Connection time | Chance of missing | Reads as |
|---|---|---|
| 30 min | 35% | Likely to miss |
| 45 min | 18% | High risk |
| 60 min | 11% | Some risk |
| 90 min | 5.9% | Some risk |
| 120 min | 4.0% | Low risk |
This is one leg of a connection. Gate changes and the next flight's own schedule matter too. And a connection can fail before delay is even the question — this route cancels 0.82% of the time and diverts 0.24% of the time, which a late arrival never shows up in.
Chance of missing is the share of 5,450 arrivals on this route that landed later than the connection time less 30 minutes to reach the next gate.
The worst tenth of arrivals on this route land at least 34 minutes late (90th-percentile gate arrival delay), over 5,508 operations.
Any other layover length: connection checker.
Best time to fly
IAD → IAH flights departing 5–9 AM arrived on time 88.0% of the time, against 67.3% for 3–6 PM departures, a gap of 20.7 percentage points.
By departure window
By departure hour
- 12 AM to 5 AM: too few flights to score
- 6 AM: 91.3% on time from 1,103 flights
- 7 AM: too few flights to score
- 8 AM: 84.8% on time from 1,127 flights
- 9 AM to 11 AM: too few flights to score
- 12 PM: 84.6% on time from 870 flights
- 1 PM: 86.8% on time from 247 flights
- 2 PM to 4 PM: too few flights to score
- 5 PM: 67.8% on time from 1,080 flights
- 6 PM to 9 PM: too few flights to score
- 10 PM: 76.7% on time from 788 flights
- 11 PM: too few flights to score
Departure windows with fewer than 120 flights are not scored.
Why IAD → IAH runs late
July 2023 – July 2026
crew, maintenance, boarding and fueling, all within the carrier’s control
airspace and airport capacity, including weather-driven flow control
the inbound aircraft was late, so this flight started late
weather severe enough to stop this flight specifically
Share of the delay minutes US DOT attributed to each cause for IAD → IAH. Only delays of 15 minutes or more are attributed.
Airlines on this route
Carriers with at least 200 flights, by the airline that operated each one.
| Carrier | Flights | On time | Cancelled | Median delay | Severe |
|---|---|---|---|---|---|
| United Airlines | 5,508 | 81.0% | 0.82% | -7 min | 6.0% |
Flights on this route
Flight numbers with at least 600 operations here and still on the schedule.
| Flight | Scheduled | Operations | On time |
|---|---|---|---|
| UA1524 United Airlines | 8:30 AM | 606 | 87.2% |
Weekly and seasonal patterns
By day of week
Tuesday is historically the most reliable day and Saturday the least, a gap of 4.3 percentage points.
By month
- Jan: 79.3%
- Feb: 88.3%
- Mar: 86.8%
- Apr: 82.9%
- May: 73.8%
- Jun: 74.1%
- Jul: 69.9%
- Aug: 80.8%
- Sep: 86.6%
- Oct: 87.1%
- Nov: 89.3%
- Dec: 79.6%
July is historically the weakest month and November the strongest, a spread of 19.4 percentage points.
Reliability over time
July 2023 – July 2026
- July 2023: 66.2% from 155 flights
- August 2023: 81.0% from 155 flights
- September 2023: 79.6% from 148 flights
- October 2023: 90.3% from 154 flights
- November 2023: too few flights to score (118)
- December 2023: 87.7% from 122 flights
- January 2024: 73.9% from 121 flights
- February 2024: too few flights to score (117)
- March 2024: 87.0% from 124 flights
- April 2024: 78.2% from 120 flights
- May 2024: 68.8% from 156 flights
- June 2024: 75.7% from 150 flights
- July 2024: 62.6% from 155 flights
- August 2024: 82.2% from 155 flights
- September 2024: 85.9% from 150 flights
- October 2024: 89.5% from 155 flights
- November 2024: 91.9% from 148 flights
- December 2024: 74.5% from 138 flights
- January 2025: 74.0% from 130 flights
- February 2025: too few flights to score (114)
- March 2025: 88.9% from 153 flights
- April 2025: 81.6% from 180 flights
- May 2025: 69.6% from 186 flights
- June 2025: 68.8% from 176 flights
- July 2025: 72.1% from 155 flights
- August 2025: 79.3% from 174 flights
- September 2025: 92.3% from 195 flights
- October 2025: 82.2% from 180 flights
- November 2025: 86.5% from 148 flights
- December 2025: 77.7% from 139 flights
- January 2026: 89.5% from 129 flights
- February 2026: too few flights to score (112)
- March 2026: 84.5% from 144 flights
- April 2026: 88.4% from 146 flights
- May 2026: 83.1% from 167 flights
- June 2026: 78.0% from 180 flights
- July 2026: 78.0% from 159 flights
Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 84.2% against 79.8% in the 12 months before — improving by 4.4 percentage points.
Data and methodology
Calculated by FlyerIntel from 5,508 IAD → IAH flight records from the US DOT Bureau of Transportation Statistics, covering July 2023 – July 2026. Late means 15 or more minutes past scheduled arrival; cancelled and diverted flights are left out of on-time rates.
Full methodology · Data sources · Report a problem
Related research: How Long a Layover Needs to Be · Two Airlines on One Route · Best Time of Day to Fly From Major US Airports
Analysis last recomputed