Route reliability record
DEN→RDU
Denver to Raleigh
- Flights
- 1,732
- Period
- September 2025 to August 2026
- Distance
- 1,436 mi
- Carriers
- 3
This route lands a B+, about a point worse than the national rate of 77.3%. About one flight in four arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 1,732 DEN to RDU flights, of which United Airlines flew 727 at 82.3% on time.
Best time to fly DEN to RDU: a 5am–8am departure, ideally on a Tuesday. Flights in that window arrived on time 92.9% of the time and Tuesday flights 81.5%, against 76.0% for the route overall.
The US average over the same twelve months is 77.3%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
76.0%
Arrivals under 15 minutes late, of 1,717 completed flights
Avg delay
57 min
Across delayed arrivals only, not all flights
Cancelled
0.69%
National rate is 1.89%
Best carrier
United
82.3% on time across 727 flights
These figures cover 1,732 flights between September 2025 and August 2026. The median arrival is 2 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 DEN to RDU
The choice of carrier is not cosmetic here. United Airlines arrives on time 82.3% of the time; Southwest Airlines manages 64.8%. Sample sizes sit next to every figure, because a two-point gap across 709 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Frontier Airlinesthin sample | 296 | 87.4% | 56 min | 1.01% | A |
| United Airlines | 727 | 82.3% | 66 min | 0.41% | B+ |
| Southwest Airlines | 709 | 64.8% | 52 min | 0.85% | D+ |
The spread between United and Southwest is 18 points, wide enough that it should decide the booking. On a hundred trips that is 18 more arrivals inside the on-time window.
Flight by flight
Flights on DEN 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.
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Best ways to make this trip
The most reliable ways to fly Denver to Raleigh
Every airline on this route, ranked by how often a scheduled flight actually operated and arrived on time, with its best departure time and most punctual flight number. No nearby airport pair beat these.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. DEN → RDUDenver to Raleigh | United Airlines | 82.0% | 82.3% | 0.41% | 8am–11am, Tue | UA 2269 09:50 |
| 2. DEN → RDUDenver to Raleigh | Southwest Airlines | 64.2% | 64.8% | 0.85% | 2pm–5pm, Wed | — |
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 34 points, against 18 points between the best and worst carrier.
- 5am–8am113 flights92.9%
- 8am–11am617 flights84.0%
- 11am–2pm267 flights78.9%
- 2pm–5pm69 flights77.6%
- 5pm–8pm634 flights64.8%
- 8pm–5am32 flights59.4%
Scale runs 50% to 100%.
The 8pm–5am window is where this operation falls apart: 59.4% on time, against 92.9% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 5pm–8pm window is the busiest, with 634 flights scheduled in it.
Explore
Filter DEN 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 DEN to RDU, the best departure window is 5am–8am at 92.9% on time and the worst is 8pm–5am at 59.4%, a wide gap of 33.5 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am92.9%
- 8–11am84.0%
- 11am–2pm78.9%
- 2–5pm77.6%
- 5–8pm64.8%
- 8pm–5am59.4%
best all US flightsScale 50% to 95%.
Across the year
When delays peak on this route
This route's year swings by 21 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 66.0% on time, 21 points below January, the best at 86.9%. 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. July was the busiest month here, with 157 flights.
Across the week, Tuesday is the strongest day at 81.5% on time and Thursday the weakest at 71.3%, a spread of 10 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 53% of the 23,000 delay minutes carriers reported here, and the remaining four split what is left.
- 53%Late-arriving aircraft
- 30%Carrier
- 15%National Airspace System
- 2%Extreme weather
53% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 23,000 reported delay minutes here, that single category outweighs weather by 31 to one. The split is drawn from 23,466 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 92.9% on time here.
Cancellations are rare at 0.69%, below the national 1.89% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.
Connections and stage length
What a delay here actually costs
7.2% 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 1,436 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 is a different operation and performs like one: it runs 81.9% on time across 1,734 flights, 6 points above this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 6 points of difference.
The sample behind these figures is 1,732 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. January runs 86.9% on time and June 66.0%, a swing of 21 points. If the dates move at all, move them out of June before you think about anything else. 1,717 completed flights over 12 months sit behind that.
Common questions
DEN to RDU questions
How often is DEN to RDU delayed?
About one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 24.0% of the 1,732 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on DEN to RDU?
United Airlines leads at 82.3% on time across 727 flights. Southwest Airlines is at the other end on 64.8%, a gap of 18 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on DEN to RDU?
The 5am–8am departure window is the strongest at 92.9% on time. The 8pm–5am window is the weakest at 59.4%, 34 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 DEN to RDU?
June is the weakest month at 66.0% on time, compared with 86.9% in January. Across the year that is 21 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 DEN — the return legseparate record
- Denver International (DEN) delay statistics
- Raleigh-Durham International (RDU) delay statistics
- Frontier Airlines on DEN to RDU87.4%
- United Airlines on DEN to RDU82.3%
- Southwest Airlines on DEN to RDU64.8%
- DEN to PHX, a related route75.6%
- ATL to RDU, a related route80.0%
- DEN to SLC, a related route78.2%
- Frontier Airlines on-time record87.4%
- United Airlines on-time record82.3%
- Southwest Airlines on-time record64.8%
- Same route, different airline: where the carrier you pick matters most
- Why the first flight of the morning is statistically safest
Direction matters. DEN to RDU and RDU to DEN 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.