Carrier route record
UAATL→DEN
United Airlines · Atlanta to Denver
- Flights
- 967
- Period
- July 2025 to June 2026
- Share of route
- 17%
- Carriers
- 4
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on ATL to DEN 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 8 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 967 flights. The strongest carrier on the route with a full sample, Delta Air Lines, flew 2,805 at 78.1% on time.
Set against the rest of the country, United's ATL to DEN record is 8 points better than the US average of 77.6%. That gap is worth roughly 80 fewer late arrivals for every thousand flights.
Key figures
On time
85.6%
Arrivals under 15 minutes late, of 956 completed flights
Avg delay
78 min
Across delayed arrivals only, not all flights
Cancelled
0.41%
National rate is 1.81%
Whole route
77.6%
Every carrier on ATL to DEN, 5,589 flights
These figures cover 967 flights between July 2025 and June 2026. The median arrival is 9 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
United against every carrier on ATL to DEN
United flew 967 of the 5,589 flights on ATL to DEN, about 17% of it. Its 85.6% on time is 8 points better than the route as a whole, which runs 77.6%. Ranked by on-time rate it is first of four carriers on the route, where the range runs from United at 85.6% to Frontier at 70.9%.
The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 78.1% of the time; Frontier Airlines manages 70.9%. Sample sizes sit next to every figure, because a two-point gap across 738 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines (this page) | 967 | 85.6% | 78 min | 0.41% | A+ |
| Delta Air Lines | 2,805 | 78.1% | 52 min | 1.11% | B |
| Southwest Airlines | 1,079 | 73.4% | 54 min | 1.11% | C |
| Frontier Airlines | 738 | 70.9% | 82 min | 1.36% | C |
Delta leads Frontier by 7 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
Flight by flight
United flight numbers on ATL to DEN
Departure window
When United runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 11 points, against 7 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am79 flights91.0%
- 8am–11am264 flights87.3%
- 11am–2pm260 flights89.6%
- 2pm–5pm364 flights80.2%
- 5pm–8pm—
- 8pm–5am—
Scale runs 70% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 91.0% of the time, against 80.2% for the afternoon window. That is 11 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 2pm–5pm window is the busiest, with 364 flights scheduled in it.
Across the year
United on ATL to DEN through the year
April is the best month on the calendar at 91.7% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. July was the busiest month here, with 114 flights.
Across the week, Friday is the strongest day at 91.2% on time and Sunday the weakest at 82.0%. 9 points is a smaller lever than departure hour, but it is free.
Delay causes
Why United runs late on this route
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 11,000 reported delay minutes.
- 33%Late-arriving aircraft
- 32%Carrier
- 32%National Airspace System
- 1%Extreme weather
- 1%Security
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 91.0% on time here. The split is drawn from 10,773 reported delay minutes.
No single cause dominates. late-arriving aircraft at 33%, carrier at 32% and national airspace system at 32% split the 11,000 reported delay minutes between them. An even spread like this usually means the operation is running close to its designed capacity with no one obvious weak point, and it is the hardest pattern for a traveller to route around.
Cancellations are rare at 0.41%, below the national 1.81% 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 costs
6.0% 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.
The 1,199 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. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
The return leg is a different operation and performs like one: it runs 78.0% on time across 967 flights, 8 points below 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 8 points of difference.
One caution: this is a thin sample. 967 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.
What to do with this
Booking United on ATL to DEN
Put together: treat all of this as provisional. 967 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 85.6% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 956 completed flights over 12 months sit behind that.
Related
Where to go next
- ATL to DEN, every carrier
- United on DEN to ATL, the return leg
- Delta Air Lines on ATL to DEN78.1%
- Southwest Airlines on ATL to DEN73.4%
- Frontier Airlines on ATL to DEN70.9%
- United Airlines network-wide record
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Denver International (DEN) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
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.