Carrier route record

F9MIA→DEN

Frontier Airlines · Miami to Denver

Flights: 355
Period: September 2025 to August 2026
Share of route: 15%
Carriers: 4

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

Frontier on MIA to DEN lands a B+, 6 points better than the national rate of 77.3%. About one flight in six arrives 15 minutes late or worse, and those flights are late by an hour and a half on average. That rests on 355 flights. The strongest carrier on the route with a full sample, United Airlines, flew 877 at 83.0% on time.

Set against the rest of the country, Frontier's MIA to DEN record is 6 points better than the US average of 77.3%. That gap is worth roughly 59 fewer late arrivals for every thousand flights.

On time

83.2%

Arrivals under 15 minutes late, of 351 completed flights

Avg delay

91 min

Across delayed arrivals only, not all flights

Cancelled

0.85%

National rate is 1.89%

Whole route

76.8%

Every carrier on MIA to DEN, 2,444 flights

These figures cover 355 flights between September 2025 and August 2026. The median arrival is 14 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.

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Carrier by carrier

Frontier against every carrier on MIA to DEN

Frontier flew 355 of the 2,444 flights on MIA to DEN, about 15% of it. Its 83.2% on time is 6 points better than the route as a whole, which runs 76.8%. Ranked by on-time rate it is first of four carriers on the route, where the range runs from Frontier at 83.2% to Southwest at 54.5%. 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 83.0% of the time; American Airlines manages 76.1%. Sample sizes sit next to every figure, because a two-point gap across 889 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	355	83.2%	91 min	0.85%	B+
United Airlines	877	83.0%	73 min	0.11%	B+
American Airlines	889	76.1%	58 min	0.90%	B+
Southwest Airlinesthin sample	323	54.5%	61 min	0.00%	F+

United leads American by 7 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 127906:0085.4% · 339 flights

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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 355 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 83.2% is the reliable figure here.

Across the year

Frontier on MIA to DEN through the year

Jul–Sep 202521 flights—
Oct–Dec 202580 flights84.6%
Jan–Mar 2026101 flights74.0%
Apr–Jun 202691 flights84.4%
Jul–Sep 202662 flights90.3%

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 83.2% on time across 355 flights.

Frontier on MIA to DEN did not run the same all year. Its best quarter was Jul–Sep 2026 at 90.3% on time and its weakest Jan–Mar 2026 at 74.0%, a swing of 16 points on roughly 89 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 74.6%, a spread of 18 points.

Arrival by arrival

How late Frontier on MIA to DEN runs when it is late

Frontier on MIA to DEN often beats the schedule: 168 of 351 completed flights, 48%, arrived 15 minutes or more early. The 59 late arrivals split 21 under half an hour, 20 between 30 and 60 minutes, and 18 an hour or more.

15+ min early168 flights47.9%
Within 15 min124 flights35.3%
15–29 min late21 flights6.0%
30–59 min late20 flights5.7%
1–2 hours late10 flights2.8%
2+ hours late8 flights2.3%

Scale runs 0% to 100%.

Share of 351 completed flights by arrival against schedule.

17 of 64 late departures made up the time and arrived on time, 27% of them. 12 flights left on time and still arrived late.

The worst days

Worst days for Frontier on MIA to DEN

The latest arrival of the period was on 27 October 2025, 18 hours 43 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. Three of the five worst days fell in March 2026.

The latest arrivals of Frontier on MIA to DEN in the period
Date	Arrived late by	Largest filed cause
27 October 2025	18 hours 43 minutes	Late-arriving aircraft
23 March 2026	16 hours 27 minutes	Late-arriving aircraft
17 March 2026	5 hours 1 minute	National Airspace System
27 March 2026	4 hours 51 minutes	Late-arriving aircraft
17 May 2026	3 hours 21 minutes	Carrier

Delay causes

Why Frontier runs late on this route

Late-arriving aircraft accounts for 60% of the 5,375 delay minutes carriers reported here, and the remaining four split what is left.

Late-arriving aircraft
60%
Carrier
26%
National Airspace System
14%

60% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 5,375 reported delay minutes here, that single category outweighs weather by 60 to one. The split is drawn from 5,375 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 87.4% on time here.

Cancellations are rare at 0.85%, below the national 1.89% 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

5.1% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last an hour and a half, 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 73.9% on time across 353 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. 355 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. 355 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 83.2% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 351 completed flights over 12 months sit behind that.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated 22 October 2026; recomputed monthly. How this data is collected.

Key figures