Flight number record

F9 1279

Frontier Airlines · Miami to Denver

Route: MIA → DEN
Departs: 06:00
Flights: 335
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s F9 1279, check with Frontier Airlines.

F9 1279 earns an A. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 8 points better than the national rate of 77.6%. When something does go wrong the average delay runs about 2.1 hours. That rests on 335 flights, with a median arrival 14 minutes early.

Set against the rest of the country, F9 1279's record is 8 points better than the US average of 77.6%. That gap is worth roughly 75 fewer late arrivals for every thousand flights.

On time

85.1%

Arrivals under 15 minutes late, of 328 completed flights

Avg delay

126 min

Across delayed arrivals only, not all flights

Cancelled

1.49%

National rate is 1.81%

1 hour+ late

5.5%

National rate is 8.1%

These figures cover 335 flights between July 2025 and June 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.

Schedule

When F9 1279 flies

F9 1279 flies MIA to DEN without a single fixed slot. Its most common scheduled departure was 06:00, used on 141 of 335 flights, with 06:30 (35 flights) and 05:50 (34 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 06:00141 flights42.1%
Departs 06:3035 flights10.4%
Departs 05:5034 flights10.1%

Scale runs 0% to 100%. Rows with fewer than 30 flights show a dash.

Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.

A 06:00 departure sits in the 5am–8am window. Across every US flight scheduled in that window the on-time rate is 89.3%, and F9 1279 runs 4 points worse at 85.1%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.

Against the route

F9 1279 next to MIA to DEN

Every carrier on MIA to DEN combined arrived on time 77.1% of the time across 2,491 flights, so F9 1279 is 8 points ahead of it. Across its whole network Frontier Airlines managed 73.2%, which this flight beats by 12 points.

F9 1279 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
F9 1279thin sample	335	85.1%	126 min	1.49%	A
All Frontier Airlines on MIA–DENthin sample	351	82.8%	112 min	1.42%	B
All carriers on MIA–DEN	2,491	77.1%	68 min	0.52%	B+
Frontier Airlines, whole network	205,332	73.2%	84 min	1.85%	C

Across the year

F9 1279 quarter by quarter

F9 1279 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 78.4%, a swing of 12 points on roughly 84 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.

Jul–Sep 202579 flights90.8%
Oct–Dec 202576 flights87.8%
Jan–Mar 202689 flights78.4%
Apr–Jun 202691 flights84.4%

Scale runs 70% to 95%. Rows with fewer than 30 flights show a dash.

By weekday, F9 1279 did best on Thursday at 92.3% on time and worst on Tuesday at 78.4%. Each day rests on about 48 flights, so a gap of 14 points is worth noticing but could still narrow in another year.

Delay causes

Why F9 1279 runs late

One category carries most of the weight here. Late-arriving aircraft accounts for 63% of the 6,182 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
26%
National Airspace System
11%
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 6,182 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 6,182 delay minutes reported on F9 1279.

Cancellations sit at 1.49% against a national 1.81%, which is ordinary. Diversions add another 0.60%.

Connections and routes

What a delay on this flight costs

5.5% 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 about 2.1 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.

Every one of the 335 flights under F9 1279 in the data flew MIA to DEN. The number was not reused on any other city pair, which makes this a clean record of one route.

One caution: this is a thin sample. 335 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 F9 1279

For a booking, F9 1279 has one of the better records a US domestic flight can show: 85.1% on time and 1.49% cancelled. That is a base rate, not a promise about any single day.

Where to go next

A flight number here means Frontier Airlines’s own number as it reports to the DOT. How the figures are computed is on the methodology page.

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