Carrier route record

AAMIA→DEN

American Airlines · Miami to Denver

Flights: 889
Period: September 2025 to August 2026
Share of route: 36%
Carriers: 4

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

American on MIA to DEN lands a B+, about a point worse than the national rate of 77.3%. About one flight in four arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 889 flights, with a median arrival 7 minutes early.

The US average over the same twelve months is 77.3%, so there is little to separate American on MIA to DEN from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

76.1%

Arrivals under 15 minutes late, of 877 completed flights

Avg delay

58 min

Across delayed arrivals only, not all flights

Cancelled

0.90%

National rate is 1.89%

Whole route

76.8%

Every carrier on MIA to DEN, 2,444 flights

These figures cover 889 flights between September 2025 and August 2026. The median arrival is 7 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

American against every carrier on MIA to DEN

American flew 889 of the 2,444 flights on MIA to DEN, about 36% of it. Its 76.1% on time is about level with the route as a whole at 76.8%. Ranked by on-time rate it is number three of four carriers on the route, where the range runs from Frontier at 83.2% to Southwest at 54.5%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.

Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.

On-time performance by carrier on MIA to DEN
Airline	Flights	On time	Avg delay	Cancelled	Grade
Frontier Airlinesthin sample	355	83.2%	91 min	0.85%	B+
United Airlines	877	83.0%	73 min	0.11%	B+
American Airlines (this page)	889	76.1%	58 min	0.90%	B+
Southwest Airlinesthin sample	323	54.5%	61 min	0.00%	F+

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Departure window

When American runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 18 points, against half a point between the best and worst carrier.

5am–8am—
8am–11am327 flights85.8%
11am–2pm37 flights80.0%
2pm–5pm—
5pm–8pm160 flights74.5%
8pm–5am365 flights67.5%

Scale runs 60% to 90%. Rows with fewer than 30 flights show a dash.

Book the morning departure. Flights leaving between 8am–11am arrive on time 85.8% of the time, against 67.5% for the overnight window. That is 18 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8pm–5am window is the busiest, with 365 flights scheduled in it.

Across the year

American on MIA to DEN through the year

Darker means more delays. Figures are on-time percentages.October best, January worst

January is the weak month at 72.4% on time, against 80.3% in October. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. January was the busiest month here, with 93 flights.

Across the week, Tuesday is the strongest day at 82.9% on time and Sunday the weakest at 71.2%, a spread of 12 points.

Arrival by arrival

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

American on MIA to DEN often beats the schedule: 323 of 877 completed flights, 37%, arrived 15 minutes or more early. The 210 late arrivals split 77 under half an hour, 75 between 30 and 60 minutes, and 58 an hour or more.

15+ min early323 flights36.8%
Within 15 min344 flights39.2%
15–29 min late77 flights8.8%
30–59 min late75 flights8.6%
1–2 hours late38 flights4.3%
2+ hours late20 flights2.3%

Scale runs 0% to 100%.

Share of 877 completed flights by arrival against schedule.

49 of 207 late departures made up the time and arrived on time, 24% of them. In the other direction, 52 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at DEN.

The worst days

Worst days for American on MIA to DEN

The latest arrival of the period was on 30 January 2026, 16 hours 54 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. Four of the five worst days fell in January 2026.

The latest arrivals of American on MIA to DEN in the period
Date	Arrived late by	Largest filed cause
30 January 2026	16 hours 54 minutes	Late-arriving aircraft
3 January 2026	8 hours 27 minutes	Carrier
25 June 2026	4 hours 15 minutes	Late-arriving aircraft
26 January 2026	3 hours 31 minutes	Extreme weather
4 January 2026	3 hours 29 minutes	Late-arriving aircraft

Delay causes

Why American 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 12,000 reported delay minutes.

Late-arriving aircraft
39%
Carrier
39%
National Airspace System
16%
Extreme weather
5%
Security
1%

39% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 12,000 reported delay minutes here, that single category outweighs weather by 7 to one. The split is drawn from 12,234 reported delay minutes.

The largest share of delay minutes, 39%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 4,717 of the 12,000 delay minutes reported here.

Cancellations sit at 0.90% against a national 1.89%, which is ordinary. Diversions add another 0.45%.

Connections and stage length

What a delay here costs

6.6% 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 about an hour, 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 runs 77.8% on time across 890 flights, within 2 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.

One caution: this is a thin sample. 889 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 American on MIA to DEN

Put together: treat all of this as provisional. 889 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 76.1% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 877 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