Carrier route record

F9CLE→DEN

Frontier Airlines · Cleveland to Denver

Flights: 294
Period: July 2025 to June 2026
Share of route: 16%
Carriers: 3

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

Frontier on CLE to DEN sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 7 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 294 flights. The strongest carrier on the route with a full sample, United Airlines, flew 942 at 88.1% on time.

The national on-time rate over the same period is 77.6%, so Frontier on CLE to DEN runs 7 points behind the country as a whole. Across a thousand flights that is about 74 extra late arrivals.

On time

70.2%

Arrivals under 15 minutes late, of 289 completed flights

Avg delay

61 min

Across delayed arrivals only, not all flights

Cancelled

1.70%

National rate is 1.81%

Whole route

82.0%

Every carrier on CLE to DEN, 1,840 flights

These figures cover 294 flights between July 2025 and June 2026. Beyond the headline rate, 10.4% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.

Carrier by carrier

Frontier against every carrier on CLE to DEN

Frontier flew 294 of the 1,840 flights on CLE to DEN, about 16% of it. Its 70.2% on time is 12 points worse than the route as a whole, which runs 82.0%. Ranked by on-time rate it is last of three carriers on the route, where the range runs from United at 88.1% to Frontier at 70.2%.

The choice of carrier is not cosmetic here. United Airlines arrives on time 88.1% of the time; Southwest Airlines manages 78.1%. Sample sizes sit next to every figure, because a two-point gap across 604 flights means less than a ten-point one.

On-time performance by carrier on CLE to DEN
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlines	942	88.1%	64 min	0.11%	A+
Southwest Airlines	604	78.1%	59 min	0.33%	B+
Frontier Airlines (this page)thin sample	294	70.2%	61 min	1.70%	C

United leads Southwest by 10 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

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 29 points, against 10 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am7 flights—
8am–11am3 flights—
11am–2pm99 flights88.8%
2pm–5pm21 flights—
5pm–8pm55 flights63.0%
8pm–5am109 flights59.4%

Scale runs 50% to 95%. Rows with fewer than 30 flights show a dash.

The 8pm–5am window is where this operation falls apart: 59.4% on time, against 88.8% for the 11am–2pm slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 8pm–5am window is the busiest, with 109 flights scheduled in it.

Across the year

Frontier on CLE to DEN through the year

Jul–Sep 202581 flights57.0%
Oct–Dec 202573 flights62.5%
Jan–Mar 202655 flights68.5%
Apr–Jun 202685 flights90.5%

Scale runs 50% to 95%. Rows with fewer than 30 flights show a dash.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 70.2% on time across 294 flights.

Frontier on CLE to DEN did not run the same all year. Its best quarter was Apr–Jun 2026 at 90.5% on time and its weakest Jul–Sep 2025 at 57.0%, a swing of 34 points on roughly 74 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.

Across the week, Friday is the strongest day at 81.0% on time and Tuesday the weakest at 64.7%. 16 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Frontier runs late on this route

One category carries most of the weight here. Late-arriving aircraft accounts for 46% of the 5,207 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
46%
National Airspace System
37%
Carrier
15%
Extreme weather
1%

46% 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 5,207 reported delay minutes here, that single category outweighs weather by 39 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 5,207 reported delay minutes.

37% 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 1,952 minutes out of 5,207, against a national NAS share of 21%.

Cancellations sit at 1.70% against a national 1.81%, which is ordinary. Diversions add another 0.00%.

Connections and stage length

What a delay here costs

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 10.4% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.

The 1,201 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.

The return leg is a different operation and performs like one: it runs 84.1% on time across 296 flights, 14 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 14 points of difference.

One caution: this is a thin sample. 294 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 CLE to DEN

Put together: treat all of this as provisional. 294 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 70.2% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 289 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