Carrier route record

F9SLC→DEN

Frontier Airlines · Salt Lake City to Denver

Flights: 1,012
Period: July 2025 to June 2026
Share of route: 13%
Carriers: 5

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Frontier Airlines.

Frontier 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 a little over an hour on average. That is a workable record, not a spotless one. That rests on 1,012 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.

On time

78.1%

Arrivals under 15 minutes late, of 1,002 completed flights

Avg delay

73 min

Across delayed arrivals only, not all flights

Cancelled

0.89%

National rate is 1.81%

Whole route

77.8%

Every carrier on SLC to DEN, 7,757 flights

These figures cover 1,012 flights between July 2025 and June 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.

Carrier by carrier

Frontier against every carrier on SLC to DEN

Frontier flew 1,012 of the 7,757 flights on SLC to DEN, about 13% of it. Its 78.1% on time is about level with the route as a whole at 77.8%. Ranked by on-time rate it is number three 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.

On-time performance by carrier on SLC to DEN
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 (this page)	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

Frontier flight numbers on SLC to DEN

F9 386207:2078.1% · 360 flights

Departure window

When Frontier 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–8am191 flights85.7%
8am–11am187 flights70.3%
11am–2pm135 flights88.1%
2pm–5pm155 flights68.8%
5pm–8pm76 flights74.7%
8pm–5am268 flights79.6%

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 88.1% on time, ahead of 2pm–5pm at 68.8%. 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 8pm–5am window is the busiest, with 268 flights scheduled in it.

Across the year

Frontier on SLC to DEN through the year

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

July is the worst month at 63.8% on time, 29 points below April, the best at 92.7%. 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. June was the busiest month here, with 96 flights.

Across the week, Saturday is the strongest day at 86.5% on time and Wednesday the weakest at 75.0%. 12 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Frontier runs late on this route

Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 16,000 reported delay minutes.

Late-arriving aircraft
42%
Carrier
31%
National Airspace System
25%
Extreme weather
2%

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 16,000 reported delay minutes here, that single category outweighs weather by 23 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 16,009 reported delay minutes.

Cancellations are rare at 0.89%, 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

7.5% 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 11am–2pm window matters as much as it does.

The return leg is a different operation and performs like one: it runs 81.7% on time across 1,010 flights, 4 points above this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 4 points of difference.

One caution: this is a thin sample. 1,012 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.

What to do with this

Booking Frontier on SLC to DEN

Put together: treat all of this as provisional. 1,012 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 78.1% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 1,002 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