Route reliability record
IAH→RDU
Houston to Raleigh
- Flights
- 943
- Period
- September 2025 to August 2026
- Distance
- 1,042 mi
- Carriers
- 3
This route lands a B, 6 points better than the national rate of 77.3%. About one flight in six arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 943 IAH to RDU flights, with a median arrival 7 minutes early.
Best time to fly IAH to RDU: a 11am–2pm departure, ideally on a Wednesday. Flights in that window arrived on time 91.9% of the time and Wednesday flights 91.5%, against 83.2% for the route overall.
Set against the rest of the country, this route's record is 6 points better than the US average of 77.3%. That gap is worth roughly 59 fewer late arrivals for every thousand flights.
Key figures
On time
83.2%
Arrivals under 15 minutes late, of 928 completed flights
Avg delay
67 min
Across delayed arrivals only, not all flights
Cancelled
1.27%
National rate is 1.89%
Best carrier
United
84.6% on time across 696 flights
These figures cover 943 flights between September 2025 and August 2026. The median arrival is 7 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
Which airline is most reliable on IAH to RDU
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 | 696 | 84.6% | 61 min | 0.86% | B+ |
| Frontier Airlinesthin sample | 246 | 79.4% | 82 min | 2.44% | B |
| SkyWest Airlinesthin sample | 1 | 0.0% | 22 min | 0.00% | F+ |
Flight by flight
Flights on IAH to RDU
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
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
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 22 points, against half a point between the best and worst carrier.
- 5am–8am—
- 8am–11am146 flights84.7%
- 11am–2pm326 flights91.9%
- 2pm–5pm68 flights69.7%
- 5pm–8pm403 flights77.9%
- 8pm–5am—
Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.
The best window here is not the first bank but the 11am–2pm slot at 91.9% on time, ahead of 2pm–5pm at 69.7%. Where the curve peaks mid-day rather than at dawn, the constraint is usually congestion at one end rather than the aircraft's own rotation. The 5pm–8pm window is the busiest, with 403 flights scheduled in it.
Explore
Filter IAH to RDU by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On IAH to RDU, the best departure window is 11am–2pm at 91.9% on time and the worst is 2pm–5pm at 69.7%, a wide gap of 22.2 points. All US flights leaving 11am–2pm ran 78.3%.
- 5–8am—
- 8–11am84.7%
- 11am–2pm91.9%
- 2–5pm69.7%
- 5–8pm77.9%
- 8pm–5am—
best all US flightsScale 60% to 95%. Cells under 30 flights show a dash.
Across the year
When delays peak on this route
This route's year swings by 22 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
June is the worst month at 71.2% on time, 22 points below September, the best at 93.2%. 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. March was the busiest month here, with 100 flights.
Across the week, Wednesday is the strongest day at 91.5% on time and Monday the weakest at 78.6%, a spread of 13 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 55% of the 10,000 delay minutes carriers reported here, and the remaining four split what is left.
- 55%Late-arriving aircraft
- 32%Carrier
- 10%National Airspace System
- 3%Extreme weather
55% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 10,000 reported delay minutes here, that single category outweighs weather by 21 to one. The split is drawn from 10,477 reported delay minutes.
Cancellations sit at 1.27% against a national 1.89%, which is ordinary. Diversions add another 0.32%.
Connections and stage length
What a delay here actually costs
5.9% 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 1,042 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 85.9% on time across 943 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. 943 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.
Work out the risk of missing a connection in RDU after this flight
What to do with this
Booking this route
Put together: treat all of this as provisional. 943 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 83.2% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 928 completed flights over 12 months sit behind that.
Common questions
IAH to RDU questions
How often is IAH to RDU delayed?
About one flight in six arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 16.8% of the 943 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
How reliable is IAH to RDU compared with the rest of the country?
83.2% of flights arrive on time here against a national 77.3%, a difference of 6 points in its favour. That is worth a B on this site's grading scale.
What time of day has the fewest delays on IAH to RDU?
The 11am–2pm departure window is the strongest at 91.9% on time. The 2pm–5pm window is the weakest at 69.7%, 22 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are June delays on IAH to RDU?
June is the weakest month at 71.2% on time, compared with 93.2% in September. Across the year that is 22 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- RDU to IAH — the return legseparate record
- George Bush Intercontinental (IAH) delay statistics
- Raleigh-Durham International (RDU) delay statistics
- United Airlines on IAH to RDU84.6%
- Frontier Airlines on IAH to RDU79.4%
- IAH to ORD, a related route75.1%
- ATL to RDU, a related route80.0%
- IAH to DFW, a related route76.4%
- United Airlines on-time record84.6%
- Frontier Airlines on-time record79.4%
- SkyWest Airlines on-time record0.0%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
Direction matters. IAH to RDU and RDU to IAH are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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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.