Flight number record
F9 1279
Frontier Airlines · Miami to Denver
- Route
- MIA → DEN
- Departs
- 06:00
- Flights
- 339
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 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 77.3%. When something does go wrong the average delay runs close to two hours. That rests on 339 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 77.3%. That gap is worth roughly 81 fewer late arrivals for every thousand flights.
Key figures
On time
85.4%
Arrivals under 15 minutes late, of 335 completed flights
Avg delay
101 min
Across delayed arrivals only, not all flights
Cancelled
0.88%
National rate is 1.89%
1 hour+ late
4.8%
National rate is 8.3%
These figures cover 339 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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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 147 of 339 flights, with 06:30 (35 flights) and 05:50 (34 flights) next.
- Departs 06:00147 flights43.4%
- Departs 06:3035 flights10.3%
- Departs 05:5034 flights10.0%
Scale runs 0% to 100%.
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 85.4%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.
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Against the route
F9 1279 next to MIA to DEN
Every carrier on MIA to DEN combined arrived on time 76.8% of the time across 2,444 flights, so F9 1279 is 9 points ahead of it. Across its whole network Frontier Airlines managed 72.7%, which this flight beats by 13 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| F9 1279thin sample | 339 | 85.4% | 101 min | 0.88% | A+ |
| All Frontier Airlines on MIA–DENthin sample | 355 | 83.2% | 91 min | 0.85% | B+ |
| All carriers on MIA–DEN | 2,444 | 76.8% | 66 min | 0.49% | B+ |
| Frontier Airlines, whole network | 213,022 | 72.7% | 84 min | 2.05% | C |
Across the year
F9 1279 quarter by quarter
F9 1279 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 78.4%, a swing of 12 points on roughly 85 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 202521 flights—
- Oct–Dec 202576 flights87.8%
- Jan–Mar 202689 flights78.4%
- Apr–Jun 202691 flights84.4%
- Jul–Sep 202662 flights90.3%
Scale runs 70% to 95%. Rows with fewer than 30 flights show a dash.
By weekday, F9 1279 ranged from 80.8% on Monday to 92.3% on Thursday. With about 48 flights behind each day, a spread of 12 points is inside normal variation, so the day you fly is not worth changing for this flight.
Arrival by arrival
How late F9 1279 runs when it is late
F9 1279 often beats the schedule: 164 of 335 completed flights, 49%, arrived 15 minutes or more early. The 49 late arrivals split 15 under half an hour, 18 between 30 and 60 minutes, and 16 an hour or more.
- 15+ min early164 flights49.0%
- Within 15 min122 flights36.4%
- 15–29 min late15 flights4.5%
- 30–59 min late18 flights5.4%
- 1–2 hours late8 flights2.4%
- 2+ hours late8 flights2.4%
Scale runs 0% to 100%.
Share of 335 completed flights by arrival against schedule.
16 of 55 late departures made up the time and arrived on time, 29% of them. 10 flights left on time and still arrived late.
The worst days
Worst days for F9 1279
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.
| 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 F9 1279 runs late
Late-arriving aircraft accounts for 60% of the 4,954 delay minutes carriers reported here, and the remaining four split what is left.
- 60%Late-arriving aircraft
- 27%Carrier
- 13%National Airspace System
60% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 4,954 reported delay minutes here, that single category outweighs weather by 60 to one. The split is drawn from 4,954 delay minutes reported on F9 1279.
Cancellations are rare at 0.88%, 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 routes
What a delay on this flight costs
Badly late arrivals are rare here: only 4.8% land an hour or more behind schedule, against 8.3% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
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 339 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. 339 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: 85.4% on time and 0.88% cancelled. That is a base rate, not a promise about any single day.
Related
Where to go next
- MIA to DEN, every carrier and departure
- DEN to MIA, the return direction
- Miami International (MIA) delay statistics
- Denver International (DEN) delay statistics
- Frontier Airlines on-time record
- Every Frontier Airlines flight number with a record
- The most and least reliable flight numbers in the US
- Why the first flight of the morning is statistically safest
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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.