Carrier route record

UADEN→SLC

United Airlines · Denver to Salt Lake City

Flights: 1,331
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 DEN to SLC lands a B+, level with the national rate of 77.6%. Roughly one flight in four 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 1,331 flights. The strongest carrier on the route with a full sample, Delta Air Lines, flew 1,689 at 82.3% on time.

Delta Air Lines is the most reliable of the four carriers covered here at 82.3% on time across 1,689 flights.

On time

77.5%

Arrivals under 15 minutes late, of 1,327 completed flights

Avg delay

58 min

Across delayed arrivals only, not all flights

Cancelled

0.15%

National rate is 1.81%

Whole route

77.5%

Every carrier on DEN to SLC, 7,758 flights

These figures cover 1,331 flights between July 2025 and June 2026. The median arrival is 3 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 DEN to SLC

United flew 1,331 of the 7,758 flights on DEN to SLC, about 17% of it. Its 77.5% on time is about level with the route as a whole at 77.5%. Ranked by on-time rate it is number four of five carriers on the route, where the range runs from Delta at 82.3% to Southwest at 71.2%.

The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 82.3% of the time; Southwest Airlines manages 71.2%. Sample sizes sit next to every figure, because a two-point gap across 2,329 flights means less than a ten-point one.

On-time performance by carrier on DEN to SLC
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines	1,689	82.3%	81 min	0.41%	B+
Frontier Airlines	1,010	81.7%	60 min	0.50%	B+
SkyWest Airlines	1,399	79.4%	64 min	0.86%	B+
United Airlines (this page)	1,331	77.5%	58 min	0.15%	B+
Southwest Airlines	2,329	71.2%	52 min	0.47%	C+

Delta leads Southwest by 11 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

Flight by flight

United flight numbers on DEN to SLC

UA 196311:4578.0% · 365 flights

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 23 points, against 11 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am—
8am–11am273 flights89.0%
11am–2pm505 flights80.1%
2pm–5pm205 flights75.1%
5pm–8pm346 flights66.4%
8pm–5am2 flights—

Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.

Book the morning departure. Flights leaving between 8am–11am arrive on time 89.0% 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. The 11am–2pm window is the busiest, with 505 flights scheduled in it.

Across the year

United on DEN to SLC through the year

Darker means more delays. Figures are on-time percentages.February best, July worst

July is the worst month at 66.0% on time, 22 points below February, the best at 87.7%. 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, Saturday is the strongest day at 85.3% on time and Thursday the weakest at 72.9%. 12 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 48% of the 17,000 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.

Late-arriving aircraft
48%
Carrier
32%
National Airspace System
18%
Extreme weather
2%

48% 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 17,000 reported delay minutes here, that single category outweighs weather by 22 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 17,268 reported delay minutes.

The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 89.0% on time here.

Cancellations are rare at 0.15%, 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

6.3% 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 8am–11am window matters as much as it does.

The return leg runs 78.0% on time across 1,332 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 1,331 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 DEN to SLC

Put together: the calendar is the biggest lever here, not the carrier or the hour. February runs 87.7% on time and July 66.0%, a swing of 22 points. If the dates move at all, move them out of July before you think about anything else. 1,327 completed flights over 12 months sit behind that.

Where to go next

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.

Key figures