Flight number record
F9 1500
Frontier Airlines · Ontario to Denver
- Route
- ONT → DEN
- Departs
- 06:00
- Flights
- 320
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s F9 1500, check with Frontier Airlines.
F9 1500 earns an A+. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 13 points better than the national rate of 77.3%. When something does go wrong the average delay runs a little over an hour. That rests on 320 flights, with a median arrival 11 minutes early.
Set against the rest of the country, F9 1500's record is 13 points better than the US average of 77.3%. That gap is worth roughly 129 fewer late arrivals for every thousand flights.
Key figures
On time
90.2%
Arrivals under 15 minutes late, of 317 completed flights
Avg delay
79 min
Across delayed arrivals only, not all flights
Cancelled
0.94%
National rate is 1.89%
1 hour+ late
3.5%
National rate is 8.3%
These figures cover 320 flights between September 2025 and August 2026. The median arrival is 11 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 1500 flies
F9 1500 flies ONT to DEN without a single fixed slot. Its most common scheduled departure was 06:00, used on 129 of 320 flights.
- Departs 06:00129 flights40.3%
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 1500 runs level with that at 90.2%. 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 1500 next to ONT to DEN
Every carrier on ONT to DEN combined arrived on time 81.8% of the time across 2,624 flights, so F9 1500 is 8 points ahead of it. Frontier flew 558 flights on the same city pair under all its flight numbers, including this one, and those ran 86.5% on time. Across its whole network Frontier Airlines managed 72.7%, which this flight beats by 18 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| F9 1500thin sample | 320 | 90.2% | 79 min | 0.94% | A+ |
| All Frontier Airlines on ONT–DEN | 558 | 86.5% | 99 min | 0.72% | A+ |
| All carriers on ONT–DEN | 2,624 | 81.8% | 68 min | 0.38% | B+ |
| Frontier Airlines, whole network | 213,022 | 72.7% | 84 min | 2.05% | C |
Across the year
F9 1500 quarter by quarter
F9 1500 did not run the same all year. Its best quarter was Apr–Jun 2026 at 95.6% on time and its weakest Jan–Mar 2026 at 85.6%, a swing of 10 points on roughly 80 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 20254 flights—
- Oct–Dec 202573 flights87.5%
- Jan–Mar 202690 flights85.6%
- Apr–Jun 202691 flights95.6%
- Jul–Sep 202662 flights93.3%
Scale runs 75% to 100%. Rows with fewer than 30 flights show a dash.
By weekday, F9 1500 ranged from 87.0% on Tuesday to 95.7% on Thursday. With about 46 flights behind each day, a spread of 9 points is inside normal variation, so the day you fly is not worth changing for this flight.
Arrival by arrival
How late F9 1500 runs when it is late
F9 1500 often beats the schedule: 120 of 317 completed flights, 38%, arrived 15 minutes or more early. The 31 late arrivals split 12 under half an hour, 8 between 30 and 60 minutes, and 11 an hour or more.
- 15+ min early120 flights37.9%
- Within 15 min166 flights52.4%
- 15–29 min late12 flights3.8%
- 30–59 min late8 flights2.5%
- 1–2 hours late5 flights1.6%
- 2+ hours late6 flights1.9%
Scale runs 0% to 100%.
Share of 317 completed flights by arrival against schedule.
4 of 25 late departures made up the time and arrived on time, 16% of them. 10 flights left on time and still arrived late.
The worst days
Worst days for F9 1500
The latest arrival of the period was on 21 April 2026, 6 hours 47 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The five worst days are spread across April, December and March, with no single month standing out.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 21 April 2026 | 6 hours 47 minutes | Late-arriving aircraft |
| 19 December 2025 | 4 hours 31 minutes | National Airspace System |
| 7 March 2026 | 4 hours 12 minutes | Late-arriving aircraft |
| 2 March 2026 | 3 hours 10 minutes | Carrier |
| 27 April 2026 | 2 hours 57 minutes | National Airspace System |
Delay causes
Why F9 1500 runs late
National Airspace System accounts for 43% of the 2,442 delay minutes carriers reported here, and the remaining four split what is left.
- 43%National Airspace System
- 30%Carrier
- 26%Late-arriving aircraft
- 1%Extreme weather
43% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 1,053 minutes out of 2,442, against a national NAS share of 21%. The split is drawn from 2,442 delay minutes reported on F9 1500.
Cancellations sit at 0.94% against a national 1.89%, which is ordinary. Diversions add another 0.00%.
Connections and routes
What a delay on this flight costs
Badly late arrivals are rare here: only 3.5% 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.
The 819 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty.
Every one of the 320 flights under F9 1500 in the data flew ONT 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. 320 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 1500
For a booking, F9 1500 has one of the better records a US domestic flight can show: 90.2% on time and 0.94% cancelled. That is a base rate, not a promise about any single day.
Related
Where to go next
- ONT to DEN, every carrier and departure
- DEN to ONT, the return direction
- United Airlines 2446 on the same route94.0%
- Ontario International (ONT) 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
- Worst months to fly in the US, ranked by the data
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.