Route reliability record
RDU→IAD
Raleigh to Washington
- Flights
- 1,293
- Period
- July 2025 to June 2026
- Distance
- 225 mi
- Carriers
- 2
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 77.6%. When something does go wrong the average delay runs a little over an hour. That rests on 1,293 RDU to IAD flights, with a median arrival 10 minutes early.
Best time to fly RDU to IAD: a 8am–11am departure, ideally on a Saturday. Flights in that window arrived on time 93.3% of the time and Saturday flights 92.7%, against 86.5% for the route overall.
Set against the rest of the country, this route's record is 9 points better than the US average of 77.6%. That gap is worth roughly 89 fewer late arrivals for every thousand flights.
Key figures
On time
86.5%
Arrivals under 15 minutes late, of 1,277 completed flights
Avg delay
79 min
Across delayed arrivals only, not all flights
Cancelled
1.24%
National rate is 1.81%
Best carrier
United
87.5% on time across 1,080 flights
These figures cover 1,293 flights between July 2025 and June 2026. The median arrival is 10 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 RDU to IAD
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 | 87.5% | 81 min | 1.39% | A |
| Republic Airwaysthin sample | 213 | 81.6% | 74 min | 0.47% | B+ |
Flight by flight
Flights on RDU to IAD
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.
Best ways to make this trip
The most reliable ways to fly Raleigh to Washington
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. RDU → IADRaleigh to Washington | United Airlines | 86.3% | 87.5% | 1.39% | 8am–11am, Sat | UA 2463 15:02 |
| 2. RDU → BWIRaleigh to Baltimore | Southwest Airlines | 83.8% | 85.8% | 2.35% | 5am–8am, Sat (route) | — |
| 3. RDU → DCARaleigh to Washington | Envoy Air | 64.0% | 67.2% | 4.69% | 11am–2pm, Sat | — |
| 4. RDU → DCARaleigh to Washington | PSA Airlines | 57.1% | 60.5% | 5.61% | 8am–11am, Sat | — |
| 5. RDU → DCARaleigh to Washington | Republic Airways | 56.2% | 59.4% | 5.43% | 5am–8am, Sat | — |
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 17 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–8am334 flights90.5%
- 8am–11am361 flights93.3%
- 11am–2pm23 flights—
- 2pm–5pm295 flights76.3%
- 5pm–8pm100 flights78.0%
- 8pm–5am180 flights85.0%
Scale runs 70% to 100%. Rows with fewer than 30 flights show a dash.
Book the morning departure. Flights leaving between 8am–11am arrive on time 93.3% of the time, against 76.3% for the afternoon window. That is 17 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8am–11am window is the busiest, with 361 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 15 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.
December is the weak month at 78.3% on time, against 92.9% in April. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. September was the busiest month here, with 139 flights.
Across the week, Saturday is the strongest day at 92.7% on time and Monday the weakest at 83.2%. 10 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
One category carries most of the weight here. Late-arriving aircraft accounts for 48% of the 14,000 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 48%Late-arriving aircraft
- 21%National Airspace System
- 20%Carrier
- 12%Extreme weather
Extreme weather accounts for 12% 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 1.9 times the usual weather exposure. The split is drawn from 13,602 reported delay minutes.
48% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 14,000 reported delay minutes here, that single category outweighs weather by 4 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit.
Cancellations sit at 1.24% against a national 1.81%, which is ordinary. Diversions add another 0.00%.
Connections and stage length
What a delay here actually costs
Badly late arrivals are rare here: only 4.9% land an hour or more behind schedule, against 8.1% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
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 84.3% 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 IAD 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. April runs 92.9% on time and December 78.3%, a swing of 15 points. If the dates move at all, move them out of December before you think about anything else. 1,277 completed flights over 12 months sit behind that.
Common questions
RDU to IAD questions
How often is RDU to IAD 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 13.5% 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 RDU to IAD compared with the rest of the country?
86.5% of flights arrive on time here against a national 77.6%, 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 IAD?
The 8am–11am departure window is the strongest at 93.3% on time. The 2pm–5pm window is the weakest at 76.3%, 17 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 December delays on RDU to IAD?
December is the weakest month at 78.3% on time, compared with 92.9% in April. Across the year that is 15 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
- IAD to RDU — the return legseparate record
- Raleigh-Durham International (RDU) delay statistics
- Washington Dulles International (IAD) delay statistics
- United Airlines on RDU to IAD87.5%
- Republic Airways on RDU to IAD81.6%
- RDU to ATL, a related route87.6%
- ATL to IAD, a related route76.5%
- RDU to ORD, a related route74.4%
- United Airlines on-time record87.5%
- Republic Airways on-time record81.6%
- 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. RDU to IAD and IAD to RDU 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.