Carrier route record
UASLC→DEN
United Airlines · Salt Lake City to Denver
- Flights
- 1,332
- Period
- July 2025 to June 2026
- Share of route
- 17%
- Carriers
- 5
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on SLC to DEN 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 1,332 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
78.0%
Arrivals under 15 minutes late, of 1,320 completed flights
Avg delay
61 min
Across delayed arrivals only, not all flights
Cancelled
0.38%
National rate is 1.81%
Whole route
77.8%
Every carrier on SLC to DEN, 7,757 flights
These figures cover 1,332 flights between July 2025 and June 2026. The median arrival is 6 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 SLC to DEN
United flew 1,332 of the 7,757 flights on SLC to DEN, about 17% of it. Its 78.0% on time is about level with the route as a whole at 77.8%. Ranked by on-time rate it is number four 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 | 1,690 | 79.4% | 64 min | 0.24% | B+ |
| Frontier Airlines | 1,012 | 78.1% | 73 min | 0.89% | B+ |
| United Airlines (this page) | 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.
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 21 points, against 12 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am363 flights86.4%
- 8am–11am168 flights76.6%
- 11am–2pm105 flights88.6%
- 2pm–5pm437 flights74.7%
- 5pm–8pm257 flights67.7%
- 8pm–5am2 flights—
Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.
The best window here is not the first bank but the 11am–2pm slot at 88.6% on time, ahead of 5pm–8pm at 67.7%. Where the curve peaks mid-day rather than at dawn, the constraint is usually congestion at one end rather than the aircraft's own rotation. The 2pm–5pm window is the busiest, with 437 flights scheduled in it.
Across the year
United on SLC to DEN through the year
July is the worst month at 51.8% on time, 36 points below October, the best at 87.4%. 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 141 flights.
Across the week, Tuesday is the strongest day at 86.7% on time and Friday the weakest at 71.0%. 16 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. National Airspace System accounts for 44% of the 18,000 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%National Airspace System
- 36%Late-arriving aircraft
- 16%Carrier
- 3%Extreme weather
36% 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 18,000 reported delay minutes here, that single category outweighs weather by 13 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 17,880 reported delay minutes.
44% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 7,942 minutes out of 18,000, against a national NAS share of 21%.
Cancellations are rare at 0.38%, 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
6.6% 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 11am–2pm window matters as much as it does.
The return leg runs 77.5% on time across 1,331 flights, within half a point 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 1,332 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 United on SLC to DEN
Put together: the calendar is the biggest lever here, not the carrier or the hour. October runs 87.4% on time and July 51.8%, a swing of 36 points. If the dates move at all, move them out of July before you think about anything else. 1,320 completed flights over 12 months sit behind that.
Related
Where to go next
- SLC to DEN, every carrier
- United on DEN to SLC, the return leg
- SkyWest Airlines on SLC to DEN84.6%
- Delta Air Lines on SLC to DEN79.4%
- Frontier Airlines on SLC to DEN78.1%
- Southwest Airlines on SLC to DEN72.4%
- United Airlines network-wide record
- Salt Lake City International (SLC) delay statistics
- Denver International (DEN) delay statistics
- Why the first flight of the morning is statistically safest
- Same route, different airline: where the carrier you pick matters most
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.