Carrier route record
DLSLC→DEN
Delta Air Lines · Salt Lake City to Denver
- Flights
- 1,690
- Period
- July 2025 to June 2026
- Share of route
- 22%
- Carriers
- 5
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Delta Air Lines.
Delta on SLC to DEN lands a B+, 2 points better than the national rate of 77.6%. About 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 1,690 flights. The strongest carrier on the route with a full sample, SkyWest Airlines, flew 1,395 at 84.6% on time.
SkyWest Airlines is the most reliable of the four carriers covered here at 84.6% on time across 1,395 flights.
Key figures
On time
79.4%
Arrivals under 15 minutes late, of 1,680 completed flights
Avg delay
64 min
Across delayed arrivals only, not all flights
Cancelled
0.24%
National rate is 1.81%
Whole route
77.8%
Every carrier on SLC to DEN, 7,757 flights
These figures cover 1,690 flights between July 2025 and June 2026. The median arrival is 8 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
Delta against every carrier on SLC to DEN
Delta flew 1,690 of the 7,757 flights on SLC to DEN, about 22% of it. Its 79.4% on time is 2 points better than the route as a whole, which runs 77.8%. Ranked by on-time rate it is number two of five carriers on the route, where the range runs from SkyWest at 84.6% to Southwest at 72.4%.
The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 84.6% of the time; Southwest Airlines manages 72.4%. Sample sizes sit next to every figure, because a two-point gap across 2,328 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlines | 1,395 | 84.6% | 76 min | 0.65% | B+ |
| Delta Air Lines (this page) | 1,690 | 79.4% | 64 min | 0.24% | B+ |
| Frontier Airlines | 1,012 | 78.1% | 73 min | 0.89% | B+ |
| United Airlines | 1,332 | 78.0% | 61 min | 0.38% | B+ |
| Southwest Airlines | 2,328 | 72.4% | 51 min | 0.69% | C+ |
The spread between SkyWest and Southwest is 12 points, wide enough that it should decide the booking. On a hundred trips that is 12 more arrivals inside the on-time window.
Flight by flight
Delta flight numbers on SLC to DEN
Departure window
When Delta runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 19 points, against 12 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am174 flights87.9%
- 8am–11am536 flights82.2%
- 11am–2pm359 flights84.1%
- 2pm–5pm—
- 5pm–8pm354 flights68.6%
- 8pm–5am267 flights76.4%
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 87.9% of the time, against 68.6% for the evening window. That is 19 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 536 flights scheduled in it.
Across the year
Delta on SLC to DEN through the year
July is the worst month at 58.6% on time, 31 points below May, the best at 90.1%. 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. May was the busiest month here, with 153 flights.
Across the week, Sunday is the strongest day at 83.9% on time and Thursday the weakest at 75.3%. 9 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Delta runs late on this route
One category carries most of the weight here. Carrier accounts for 50% of the 22,000 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.
- 50%Carrier
- 27%National Airspace System
- 20%Late-arriving aircraft
- 3%Extreme weather
The largest share of delay minutes, 50%, 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 11,000 of the 22,000 delay minutes reported here. The split is drawn from 22,051 reported delay minutes.
Cancellations are rare at 0.24%, 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
7.6% 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.
At 391 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 5am–8am window matters as much as it does.
The return leg runs 82.3% on time across 1,689 flights, within 3 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 1,690 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.
What to do with this
Booking Delta on SLC to DEN
Put together: the calendar is the biggest lever here, not the carrier or the hour. May runs 90.1% on time and July 58.6%, a swing of 31 points. If the dates move at all, move them out of July before you think about anything else. 1,680 completed flights over 12 months sit behind that.
Related
Where to go next
- SLC to DEN, every carrier
- Delta on DEN to SLC, the return leg
- SkyWest Airlines on SLC to DEN84.6%
- Frontier Airlines on SLC to DEN78.1%
- United Airlines on SLC to DEN78.0%
- Southwest Airlines on SLC to DEN72.4%
- Delta Air Lines network-wide record
- Salt Lake City International (SLC) delay statistics
- Denver International (DEN) delay statistics
- Same route, different airline: where the carrier you pick matters most
- 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.