Carrier route record

DLDEN→SLC

Delta Air Lines · Denver to Salt Lake City

Flights: 1,689
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 DEN to SLC lands a B+, 5 points better than the national rate of 77.6%. About one flight in six arrives 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 1,689 flights. The strongest carrier on the route with a full sample, Frontier Airlines, flew 1,010 at 81.7% on time.

Set against the rest of the country, Delta's DEN to SLC record is 5 points better than the US average of 77.6%. That gap is worth roughly 47 fewer late arrivals for every thousand flights.

On time

82.3%

Arrivals under 15 minutes late, of 1,678 completed flights

Avg delay

81 min

Across delayed arrivals only, not all flights

Cancelled

0.41%

National rate is 1.81%

Whole route

77.5%

Every carrier on DEN to SLC, 7,758 flights

These figures cover 1,689 flights between July 2025 and June 2026. The median arrival is 9 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 DEN to SLC

Delta flew 1,689 of the 7,758 flights on DEN to SLC, about 22% of it. Its 82.3% on time is 5 points better than the route as a whole, which runs 77.5%. Ranked by on-time rate it is first 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. Frontier Airlines arrives on time 81.7% 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 (this page)	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	1,331	77.5%	58 min	0.15%	B+
Southwest Airlines	2,329	71.2%	52 min	0.47%	C+

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

Flight by flight

Delta flight numbers on DEN to SLC

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

5am–8am533 flights89.1%
8am–11am90 flights88.9%
11am–2pm361 flights81.8%
2pm–5pm340 flights84.8%
5pm–8pm365 flights69.0%
8pm–5am—

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 89.1% of the time, against 69.0% for the evening window. That is 20 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5am–8am window is the busiest, with 533 flights scheduled in it.

Across the year

Delta on DEN to SLC through the year

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

July is the worst month at 64.8% on time, 24 points below September, the best at 89.1%. 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 154 flights.

Across the week, Wednesday is the strongest day at 84.7% on time and Sunday the weakest at 79.1%. 6 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 45% of the 24,000 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.

Carrier
45%
Late-arriving aircraft
45%
National Airspace System
8%
Extreme weather
2%

45% 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 24,000 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 24,023 reported delay minutes.

The largest share of delay minutes, 45%, 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 24,000 delay minutes reported here.

Cancellations are rare at 0.41%, 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

6.5% 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 a little over 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 79.4% on time across 1,690 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 1,689 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 DEN to SLC

Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 89.1% on time and July 64.8%, a swing of 24 points. If the dates move at all, move them out of July before you think about anything else. 1,678 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