Flight number record
F9 1230
Frontier Airlines · San Francisco to Denver
- Route
- SFO → DEN
- Departs
- 06:00
- Flights
- 346
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s F9 1230, check with Frontier Airlines.
F9 1230 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 12 points better than the national rate of 77.3%. When something does go wrong the average delay runs about an hour. That rests on 346 flights, with a median arrival 12 minutes early.
Set against the rest of the country, F9 1230's record is 12 points better than the US average of 77.3%. That gap is worth roughly 118 fewer late arrivals for every thousand flights.
Key figures
On time
89.1%
Arrivals under 15 minutes late, of 340 completed flights
Avg delay
58 min
Across delayed arrivals only, not all flights
Cancelled
1.73%
National rate is 1.89%
1 hour+ late
3.2%
National rate is 8.3%
These figures cover 346 flights between September 2025 and August 2026. The median arrival is 12 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 1230 flies
F9 1230 flies SFO to DEN without a single fixed slot. Its most common scheduled departure was 06:00, used on 175 of 346 flights.
- Departs 06:00175 flights50.6%
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 1230 runs level with that at 89.1%. 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 1230 next to SFO to DEN
Every carrier on SFO to DEN combined arrived on time 74.7% of the time across 5,486 flights, so F9 1230 is 14 points ahead of it. Frontier flew 668 flights on the same city pair under all its flight numbers, including this one, and those ran 68.9% on time. Across its whole network Frontier Airlines managed 72.7%, which this flight beats by 16 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| F9 1230thin sample | 346 | 89.1% | 58 min | 1.73% | A |
| All Frontier Airlines on SFO–DEN | 668 | 68.9% | 68 min | 1.20% | C |
| All carriers on SFO–DEN | 5,486 | 74.7% | 61 min | 0.46% | C+ |
| Frontier Airlines, whole network | 213,022 | 72.7% | 84 min | 2.05% | C |
Across the year
F9 1230 quarter by quarter
Quarter by quarter F9 1230 held fairly steady: 87.9% in Oct–Dec 2025, 89.3% in Jan–Mar 2026, 92.1% in Apr–Jun 2026 and 88.1% in Jul–Sep 2026. A spread of 4 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.
- Jul–Sep 202526 flights—
- Oct–Dec 202591 flights87.9%
- Jan–Mar 202676 flights89.3%
- Apr–Jun 202691 flights92.1%
- Jul–Sep 202662 flights88.1%
Scale runs 80% to 100%. Rows with fewer than 30 flights show a dash.
By weekday, F9 1230 ranged from 82.6% on Tuesday to 92.3% on Sunday. With about 49 flights behind each day, a spread of 10 points is inside normal variation, so the day you fly is not worth changing for this flight.
Arrival by arrival
How late F9 1230 runs when it is late
F9 1230 often beats the schedule: 153 of 340 completed flights, 45%, arrived 15 minutes or more early. The 37 late arrivals split 17 under half an hour, 9 between 30 and 60 minutes, and 11 an hour or more.
- 15+ min early153 flights45.0%
- Within 15 min150 flights44.1%
- 15–29 min late17 flights5.0%
- 30–59 min late9 flights2.6%
- 1–2 hours late5 flights1.5%
- 2+ hours late6 flights1.8%
Scale runs 0% to 100%.
Share of 340 completed flights by arrival against schedule.
Time lost at the gate mostly stays lost. Of 21 departures that left 15 minutes late or more, only 2 made it up before arrival. In the other direction, 18 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 F9 1230
The latest arrival of the period was on 5 March 2026, 3 hours 43 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on four of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 5 March 2026 | 3 hours 43 minutes | Carrier |
| 19 May 2026 | 3 hours 11 minutes | Carrier |
| 12 April 2026 | 2 hours 51 minutes | Carrier |
| 7 December 2025 | 2 hours 22 minutes | Carrier |
| 25 August 2026 | 2 hours 11 minutes | Late-arriving aircraft |
Delay causes
Why F9 1230 runs late
Carrier accounts for 63% of the 2,128 delay minutes carriers reported here, and the remaining four split what is left.
- 63%Carrier
- 25%National Airspace System
- 12%Late-arriving aircraft
The largest share of delay minutes, 63%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 1,344 of the 2,128 delay minutes reported here. The split is drawn from 2,128 delay minutes reported on F9 1230.
Cancellations sit at 1.73% 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 3.2% 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 967 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 346 flights under F9 1230 in the data flew SFO 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. 346 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 1230
For a booking, read F9 1230 as 89.1% on time with 1.73% cancelled over 346 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- SFO to DEN, every carrier and departure
- DEN to SFO, the return direction
- United Airlines 1430 on the same route76.4%
- United Airlines 2348 on the same route81.9%
- United Airlines 1596 on the same route67.7%
- San Francisco International (SFO) 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.