Carrier route record

F9MIA→DEN

Frontier Airlines · Miami to Denver

Flights: 351
Period: July 2025 to June 2026
Share of route: 14%
Carriers: 4

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

Frontier on MIA to DEN 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 close to two hours on average. That is a workable record, not a spotless one. That rests on 351 flights. The strongest carrier on the route with a full sample, United Airlines, flew 932 at 82.1% on time.

Set against the rest of the country, Frontier's MIA to DEN record is 5 points better than the US average of 77.6%. That gap is worth roughly 52 fewer late arrivals for every thousand flights.

On time

82.8%

Arrivals under 15 minutes late, of 344 completed flights

Avg delay

112 min

Across delayed arrivals only, not all flights

Cancelled

1.42%

National rate is 1.81%

Whole route

77.1%

Every carrier on MIA to DEN, 2,491 flights

These figures cover 351 flights between July 2025 and June 2026. The median arrival is 13 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 MIA to DEN

Frontier flew 351 of the 2,491 flights on MIA to DEN, about 14% of it. Its 82.8% on time is 6 points better than the route as a whole, which runs 77.1%. Ranked by on-time rate it is first of four carriers on the route, where the range runs from Frontier at 82.8% to Southwest at 59.7%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.

The choice of carrier is not cosmetic here. United Airlines arrives on time 82.1% of the time; American Airlines manages 75.7%. Sample sizes sit next to every figure, because a two-point gap across 885 flights means less than a ten-point one.

On-time performance by carrier on MIA to DEN
Airline	Flights	On time	Avg delay	Cancelled	Grade
Frontier Airlines (this page)thin sample	351	82.8%	112 min	1.42%	B
United Airlines	932	82.1%	68 min	0.11%	B+
American Airlines	885	75.7%	63 min	0.79%	B+
Southwest Airlinesthin sample	323	59.7%	57 min	0.00%	D+

United leads American by 6 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

Flight by flight

Frontier flight numbers on MIA to DEN

F9 127906:0085.1% · 335 flights

Departure window

When Frontier runs best on this route

Departure time is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 351 flights.

There are not enough flights in each departure window to split Frontier's MIA to DEN record by time of day without the percentages moving on noise. The headline rate of 82.8% is the reliable figure here.

Across the year

Frontier on MIA to DEN through the year

Jul–Sep 202579 flights90.8%
Oct–Dec 202580 flights84.6%
Jan–Mar 2026101 flights74.0%
Apr–Jun 202691 flights84.4%

Scale runs 65% 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 82.8% on time across 351 flights.

Frontier on MIA to DEN did not run the same all year. Its best quarter was Jul–Sep 2025 at 90.8% on time and its weakest Jan–Mar 2026 at 74.0%, a swing of 17 points on roughly 88 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, Thursday is the strongest day at 92.3% on time and Saturday the weakest at 72.9%. 19 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 63% of the 6,603 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
63%
Carrier
25%
National Airspace System
12%
Extreme weather
0%

63% 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 6,603 reported delay minutes here, that single category outweighs weather by 63 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 6,603 reported delay minutes.

The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 87.1% on time here.

Cancellations sit at 1.42% against a national 1.81%, which is ordinary. Diversions add another 0.57%.

Connections and stage length

What a delay here costs

5.8% 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 close to two hours, which a normal layover absorbs.

At 1,709 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.

The return leg is a different operation and performs like one: it runs 73.6% on time across 349 flights, 9 points below 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 9 points of difference.

One caution: this is a thin sample. 351 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 MIA to DEN

Put together: treat all of this as provisional. 351 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 82.8% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 344 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