Route reliability record
RDU→IAH
Raleigh to Houston
- Flights
- 943
- Period
- September 2025 to August 2026
- Distance
- 1,042 mi
- Carriers
- 3
This route earns an A. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 9 points better than the national rate of 77.3%. When something does go wrong the average delay runs an hour and a half. That rests on 943 RDU to IAH flights, with a median arrival 12 minutes early.
Best time to fly RDU to IAH: a 5am–8am departure, ideally on a Tuesday. Flights in that window arrived on time 92.5% of the time and Tuesday flights 92.3%, against 85.9% for the route overall.
Set against the rest of the country, this route's record is 9 points better than the US average of 77.3%. That gap is worth roughly 86 fewer late arrivals for every thousand flights.
Key figures
On time
85.9%
Arrivals under 15 minutes late, of 932 completed flights
Avg delay
86 min
Across delayed arrivals only, not all flights
Cancelled
1.17%
National rate is 1.89%
Best carrier
United
89.1% on time across 696 flights
These figures cover 943 flights between September 2025 and August 2026. The median arrival is 12 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.
Fare search by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Carrier by carrier
Which airline is most reliable on RDU to IAH
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 | 1 | 100.0% | — | 0.00% | A+ |
| United Airlines | 696 | 89.1% | 80 min | 0.86% | A+ |
| Frontier Airlinesthin sample | 246 | 76.8% | 96 min | 2.03% | B |
Flight by flight
Flights on RDU to IAH
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 14 points, against half a point between the best and worst carrier.
- 5am–8am364 flights92.5%
- 8am–11am143 flights83.1%
- 11am–2pm49 flights81.6%
- 2pm–5pm143 flights88.7%
- 5pm–8pm219 flights78.1%
- 8pm–5am25 flights—
Scale runs 70% to 100%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 92.5% of the time, against 78.1% for the evening window. That is 14 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5am–8am window is the busiest, with 364 flights scheduled in it.
Explore
Filter RDU to IAH 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 RDU to IAH, the best departure window is 5am–8am at 92.5% on time and the worst is 5pm–8pm at 78.1%, a wide gap of 14.4 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am92.5%
- 8–11am83.1%
- 11am–2pm81.6%
- 2–5pm88.7%
- 5–8pm78.1%
- 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 18 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.
September is the best month on the calendar at 93.2% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. March was the busiest month here, with 100 flights.
Across the week, Tuesday is the strongest day at 92.3% on time and Saturday the weakest at 82.9%, a spread of 9 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 44% of the 11,000 delay minutes carriers reported here, and the remaining four split what is left.
- 44%Late-arriving aircraft
- 31%National Airspace System
- 22%Carrier
- 2%Extreme weather
44% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 11,000 reported delay minutes here, that single category outweighs weather by 20 to one. The split is drawn from 11,320 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 92.5% on time here.
Cancellations sit at 1.17% against a national 1.89%, which is ordinary. Diversions add another 0.00%.
Connections and stage length
What a delay here actually costs
5.0% 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 an hour and a half, 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 83.2% 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 IAH 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 85.9% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 932 completed flights over 12 months sit behind that.
Common questions
RDU to IAH questions
How often is RDU to IAH delayed?
About one flight in seven arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 14.1% of the 943 flights in this analysis, against 22.7% nationally. Delayed flights are late by an hour and a half on average.
How reliable is RDU to IAH compared with the rest of the country?
85.9% of flights arrive on time here against a national 77.3%, a difference of 9 points in its favour. That is worth a A on this site's grading scale.
What time of day has the fewest delays on RDU to IAH?
The 5am–8am departure window is the strongest at 92.5% on time. The 5pm–8pm window is the weakest at 78.1%, 14 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 November delays on RDU to IAH?
November is the weakest month at 75.0% on time, compared with 93.2% in September. Across the year that is 18 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
- IAH to RDU — the return legseparate record
- Raleigh-Durham International (RDU) delay statistics
- George Bush Intercontinental (IAH) delay statistics
- United Airlines on RDU to IAH89.1%
- Frontier Airlines on RDU to IAH76.8%
- RDU to ATL, a related route86.5%
- ORD to IAH, a related route76.0%
- RDU to ORD, a related route74.3%
- SkyWest Airlines on-time record100.0%
- United Airlines on-time record89.1%
- Frontier Airlines on-time record76.8%
- 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. RDU to IAH and IAH to RDU are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Embed RDU to IAH’s on-time badge on your site
Paste this into a web page. The badge shows the current on-time rate, cancellation rate and grade, and updates every month. Preview it, or build a badge for another route or airport.
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.