Carrier performance at one airport
DL→DEN
Delta Air Lines at Denver International
- Departures
- 11,605
- Period
- June 2025 to May 2026
- Routes
- 9
- Rank here
- #1 of 9
Delta Air Lines at Denver lands a B, 5 points better than the national rate of 77.4%. About one flight in six arrive 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 11,605 flights, of which Delta Air Lines flew 11,605 at 82.4% on time.
Measured against the airport rather than the country, Delta Air Lines runs 6 points ahead of the 76.0% weighted average across all carriers at DEN. That is the comparison worth making: every operator here works the same runways, the same airspace and the same weather.
Key figures
On time
82.4%
11,406 completed departures
Avg delay
79 min
Across delayed flights only
Cancelled
1.36%
At DEN, this carrier only
Rank here
#1
Of 9 carriers clearing the floor at DEN
These figures cover 12,000 flights between June 2025 and May 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.
Against the competition
Every carrier at DEN, ranked
The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 82.4% of the time; Allegiant Air manages 65.1%. Sample sizes sit next to every figure, because a two-point gap across 413 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines (this page) | 11,605 | 82.4% | 79 min | 1.36% | B |
| SkyWest Airlines | 75,448 | 79.4% | 79 min | 1.19% | B |
| United Airlines | 106,792 | 78.2% | 65 min | 0.48% | B+ |
| Frontier Airlines | 22,257 | 77.1% | 68 min | 0.76% | B+ |
| American Airlines | 8,855 | 76.6% | 104 min | 2.03% | B |
| Alaska Airlines | 2,642 | 74.3% | 58 min | 0.87% | C+ |
| Southwest Airlines | 89,073 | 69.6% | 55 min | 0.71% | C+ |
| JetBlue Airways | 1,242 | 69.0% | 91 min | 2.66% | C |
| Allegiant Air | 413 | 65.1% | 128 min | 1.45% | C |
The spread between Delta and Allegiant is 17 points, wide enough that it should decide the booking. On a hundred trips that is 17 more arrivals inside the on-time window.
Route by route
Where Delta Air Lines flies from DEN
Delta Air Lines operates 9 routes out of DEN with enough volume to report. Route records inside one carrier at one airport still spread widely, because a short shuttle and a transcontinental have very different exposure to a late inbound.
| Route | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DEN to ATL · Atlanta | 2,802 | 85.4% | 73 min | 1.18% | A |
| DEN to MSP · Minneapolis | 1,805 | 81.3% | 74 min | 0.83% | B+ |
| DEN to SLC · Salt Lake City | 1,689 | 81.8% | 85 min | 0.36% | B+ |
| DEN to DTW · Detroit | 1,258 | 85.4% | 72 min | 0.48% | A+ |
| DEN to LGA · New York | 1,038 | 78.8% | 82 min | 4.62% | B− |
| DEN to JFK · New York | 984 | 85.7% | 83 min | 2.64% | A |
| DEN to SEA · Seattle | 868 | 77.3% | 98 min | 0.92% | B+ |
| DEN to LAX · Los Angeles | 746 | 80.7% | 87 min | 1.34% | B |
| DEN to BOS · Boston | 415 | 75.7% | 58 min | 1.45% | B |
Departure window
Best time of day for this operation
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 23 points, against 17 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am3,345 flights89.5%
- 8am–11am1,161 flights84.1%
- 11am–2pm2,834 flights80.7%
- 2pm–5pm2,081 flights82.1%
- 5pm–8pm1,477 flights66.4%
- 8pm–5am707 flights87.2%
Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 89.5% of the time, against 66.4% for the evening window. That is 23 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on.
Across the year
Seasonal pattern
July is the worst month at 72.6% on time, 17 points below April, the best at 89.8%. 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.
Delay causes
What holds this operation up
- 42%Late-arriving aircraft
- 40%Carrier
- 15%National Airspace System
- 4%Extreme weather
- 0%Security
42% 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 159,000 reported delay minutes here, that single category outweighs weather by 11 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 1.36% against a national 1.80%, which is ordinary. Diversions add another 0.35%.
6.6% of arrivals land an hour or more late, close to the national 8.2%. 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 are the a little over an hour kind, which a normal layover absorbs.
The sample behind these figures is 11,605 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.
Put together: the calendar is the biggest lever here, not the carrier or the hour. April runs 89.8% on time and July 72.6%, a swing of 17 points. If the dates move at all, move them out of July before you think about anything else.
Common questions
Delta Air Lines at DEN
How often is Delta Air Lines at DEN delayed?
About one flight in six arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 17.6% of the 11,605 flights in this analysis, against 22.6% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on Delta Air Lines at DEN?
Delta Air Lines leads at 82.4% on time across 11,605 flights. Allegiant Air is at the other end on 65.1%, a gap of 17 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 Delta Air Lines at DEN?
The 5am–8am departure window is the strongest at 89.5% on time. The 5pm–8pm window is the weakest at 66.4%, 23 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 July delays on Delta Air Lines at DEN?
July is the weakest month at 72.6% on time, compared with 89.8% in April. Across the year that is 17 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
Source: US DOT Bureau of Transportation Statistics, on-time performance data, June 2025 to May 2026. Updated monthly. How this data is collected.