Carrier route record
UADEN→ATL
United Airlines · Denver to Atlanta
- 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 DEN to ATL lands a B+, level with the national rate of 77.6%. Roughly one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 967 flights. The strongest carrier on the route with a full sample, Delta Air Lines, flew 2,805 at 86.3% on time.
Delta Air Lines is the most reliable of the three carriers covered here at 86.3% on time across 2,805 flights.
Key figures
On time
78.0%
Arrivals under 15 minutes late, of 959 completed flights
Avg delay
64 min
Across delayed arrivals only, not all flights
Cancelled
0.31%
National rate is 1.81%
Whole route
80.0%
Every carrier on DEN to ATL, 5,596 flights
These figures cover 967 flights between July 2025 and June 2026. Beyond the headline rate, 8.2% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Carrier by carrier
United against every carrier on DEN to ATL
United flew 967 of the 5,596 flights on DEN to ATL, about 17% of it. Its 78.0% on time is 2 points worse than the route as a whole, which runs 80.0%. Ranked by on-time rate it is number three of four carriers on the route, where the range runs from Delta at 86.3% to Southwest at 66.3%.
The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 86.3% of the time; Southwest Airlines manages 66.3%. Sample sizes sit next to every figure, because a two-point gap across 1,080 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines | 2,805 | 86.3% | 71 min | 1.07% | A |
| Frontier Airlines | 744 | 78.9% | 61 min | 0.81% | B+ |
| United Airlines (this page) | 967 | 78.0% | 64 min | 0.31% | B+ |
| Southwest Airlines | 1,080 | 66.3% | 54 min | 0.83% | C+ |
The spread between Delta and Southwest is 20 points, wide enough that it should decide the booking. On a hundred trips that is 20 more arrivals inside the on-time window.
Flight by flight
United flight numbers on DEN to ATL
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 16 points, against 20 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am—
- 8am–11am365 flights85.6%
- 11am–2pm203 flights79.7%
- 2pm–5pm1 flights—
- 5pm–8pm364 flights69.4%
- 8pm–5am34 flights78.8%
Scale runs 60% to 90%. Rows with fewer than 30 flights show a dash.
Book the morning departure. Flights leaving between 8am–11am arrive on time 85.6% of the time, against 69.4% for the evening window. That is 16 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 365 flights scheduled in it.
Across the year
United on DEN to ATL through the year
July is the worst month at 63.7% on time, 26 points below April, the best at 90.0%. 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 114 flights.
Across the week, Tuesday is the strongest day at 83.2% on time and Thursday the weakest at 73.7%. 10 points is a smaller lever than departure hour, but it is free.
Delay causes
Why United runs late on this route
One category carries most of the weight here. Late-arriving aircraft accounts for 44% of the 13,000 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.
- 44%Late-arriving aircraft
- 36%Carrier
- 19%National Airspace System
- 2%Extreme weather
44% 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 13,000 reported delay minutes here, that single category outweighs weather by 23 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. The split is drawn from 13,454 reported delay minutes.
The largest share of delay minutes, 36%, 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 4,792 of the 13,000 delay minutes reported here.
Cancellations are rare at 0.31%, 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
8.2% 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 about 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 85.6% on time across 967 flights, 8 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 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 DEN to ATL
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 78.0% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 959 completed flights over 12 months sit behind that.
Related
Where to go next
- DEN to ATL, every carrier
- United on ATL to DEN, the return leg
- Delta Air Lines on DEN to ATL86.3%
- Frontier Airlines on DEN to ATL78.9%
- Southwest Airlines on DEN to ATL66.3%
- United Airlines network-wide record
- Denver International (DEN) delay statistics
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Same route, different airline: where the carrier you pick matters most
- Why the first flight of the morning is statistically safest
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.