Route reliability record
IAD→RDU
Washington to Raleigh
- Flights
- 1,293
- Period
- July 2025 to June 2026
- Distance
- 225 mi
- Carriers
- 2
This route earns a B. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 7 points better than the national rate of 77.6%. When something does go wrong the average delay runs a little over an hour. That rests on 1,293 IAD to RDU flights, with a median arrival 6 minutes early.
Best time to fly IAD to RDU: a 8am–11am departure, ideally on a Tuesday. Flights in that window arrived on time 91.0% of the time and Tuesday flights 89.4%, against 84.3% for the route overall.
Set against the rest of the country, this route's record is 7 points better than the US average of 77.6%. That gap is worth roughly 67 fewer late arrivals for every thousand flights.
Key figures
On time
84.3%
Arrivals under 15 minutes late, of 1,275 completed flights
Avg delay
72 min
Across delayed arrivals only, not all flights
Cancelled
1.24%
National rate is 1.81%
Best carrier
United
85.1% on time across 1,080 flights
These figures cover 1,293 flights between July 2025 and June 2026. The median arrival is 6 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.
Carrier by carrier
Which airline is most reliable on IAD 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 | 1,080 | 85.1% | 70 min | 1.11% | A |
| Republic Airwaysthin sample | 213 | 80.4% | 79 min | 1.88% | B |
Best ways to make this trip
The most reliable ways to fly Washington to Raleigh
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 4 of the top 5 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. IAD → RDUWashington to Raleigh | United Airlines | 84.2% | 85.1% | 1.11% | 8am–11am, Tue | — |
| 2. BWI → RDUBaltimore to Raleigh | Southwest Airlines | 78.9% | 80.8% | 2.40% | 5am–8am, Sat (route) | — |
| 3. DCA → RDUWashington to Raleigh | Envoy Air | 71.2% | 74.2% | 4.02% | 11am–2pm, Wed | — |
| 4. DCA → RDUWashington to Raleigh | Republic Airways | 66.2% | 70.8% | 6.46% | 8am–11am, Wed | — |
| 5. DCA → RDUWashington to Raleigh | PSA Airlines | 63.4% | 66.8% | 5.12% | 5am–8am, Fri | — |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
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 13 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–8am—
- 8am–11am322 flights91.0%
- 11am–2pm294 flights86.5%
- 2pm–5pm23 flights—
- 5pm–8pm317 flights77.7%
- 8pm–5am337 flights81.8%
Scale runs 70% to 95%. Rows with fewer than 30 flights show a dash.
Book the morning departure. Flights leaving between 8am–11am arrive on time 91.0% of the time, against 77.7% for the evening window. That is 13 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8pm–5am window is the busiest, with 337 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 14 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.
May is the best month on the calendar at 90.2% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. September was the busiest month here, with 140 flights.
Across the week, Tuesday is the strongest day at 89.4% on time and Thursday the weakest at 80.4%. 9 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 14,000 reported delay minutes.
- 39%Carrier
- 33%Late-arriving aircraft
- 14%Extreme weather
- 13%National Airspace System
Extreme weather accounts for 14% of delay minutes, well above the single-digit share typical across the system. Weather delays are lumpy: they arrive as whole bad days rather than as a steady drag, so the monthly strip above is the more useful view of the risk. The national share is 6%, so this operation carries roughly 2.2 times the usual weather exposure. The split is drawn from 14,436 reported delay minutes.
The largest share of delay minutes, 39%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 5,660 of the 14,000 delay minutes reported here.
Cancellations sit at 1.24% against a national 1.81%, which is ordinary. Diversions add another 0.15%.
Connections and stage length
What a delay here actually costs
5.1% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last a little over an hour, which a normal layover absorbs.
At 225 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 8am–11am window matters as much as it does.
The return leg runs 86.5% on time across 1,293 flights, within 2 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
The sample behind these figures is 1,293 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.
Work out the risk of missing a connection in RDU after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. May runs 90.2% on time and March 76.3%, a swing of 14 points. If the dates move at all, move them out of March before you think about anything else. 1,275 completed flights over 12 months sit behind that.
Common questions
IAD to RDU questions
How often is IAD 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 15.7% of the 1,293 flights in this analysis, against 22.4% nationally. Delayed flights are late by a little over an hour on average.
How reliable is IAD to RDU compared with the rest of the country?
84.3% of flights arrive on time here against a national 77.6%, a difference of 7 points in its favour. That is worth a B on this site's grading scale.
What time of day has the fewest delays on IAD to RDU?
The 8am–11am departure window is the strongest at 91.0% on time. The 5pm–8pm window is the weakest at 77.7%, 13 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 March delays on IAD to RDU?
March is the weakest month at 76.3% on time, compared with 90.2% in May. Across the year that is 14 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 IAD — the return legseparate record
- Washington Dulles International (IAD) delay statistics
- Raleigh-Durham International (RDU) delay statistics
- United Airlines on IAD to RDU85.1%
- Republic Airways on IAD to RDU80.4%
- IAD to ATL, a related route79.2%
- ATL to RDU, a related route80.4%
- IAD to DEN, a related route81.7%
- United Airlines on-time record85.1%
- Republic Airways on-time record80.4%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Direction matters. IAD to RDU and RDU to IAD 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.